WO2018042230A1

WO2018042230A1 - Configurable selective packet-in mechanism for openflow switches

Info

Publication number: WO2018042230A1
Application number: PCT/IB2016/055248
Authority: WO
Inventors: Faseela K; Ashutosh Bisht
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-09-01
Filing date: 2016-09-01
Publication date: 2018-03-08

Abstract

A method is implemented by a data plane device in a Software Defined Networking (SDN) network for selectively transmitting Packet-In messages in the SDN network. The method includes generating a flow entry in a flow table, where the flow entry includes a selective Packet-In action instruction that specifies a set of packet fields, receiving an incoming packet that matches the flow entry, generating a Packet-In ID based on a table ID of the flow table and a set of values in the incoming packet corresponding to the set of packet fields specified in the selective Packet-In action instruction, determining whether a Packet-In message associated with the Packet-In ID is being processed by the controller, and transmitting a Packet-In message for the incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is not being processed by the controller.

Description

CONFIGURABLE SELECTIVE PACKET-IN MECHANISM FOR OPENFLOW

SWITCHES

TECHNICAL FIELD

[0001] Embodiments of the invention relate to the field of computer networks, and more specifically, to a configurable selective Packet-In mechanism in a Software Defined Networking (SDN) network.

BACKGROUND

[0002] Software Defined Networking (SDN) is an approach to computer networking that employs a split architecture network in which the forwarding (data) plane is decoupled from the control plane. The use of a split architecture network simplifies the network devices (e.g., switches) implementing the forwarding plane by shifting the intelligence of the network into one or more controllers that oversee the switches. SDN facilitates rapid and open innovation at the network layer by providing a programmable network infrastructure.

[0003] OpenFlow is a protocol that enables controllers and switches in an SDN network to communicate with each other. OpenFlow enables dynamic programming of flow control policies in the network. An OpenFlow channel is used to exchange OpenFlow messages between an OpenFlow switch and an OpenFlow controller.

[0004] An OpenFlow switch uses a Packet-In message to transfer control of a packet to the OpenFlow controller. When a Packet-In message for a packet is sent to the OpenFlow controller, either the entire packet is included in the Packet-In message or only a portion of the packet is included in the Packet-In message, along with a buffer identifier that identifies a buffer that stores the packet.

[0005] An OpenFlow controller may respond to a Packet-In message by programming a flow entry in the OpenFlow switch, which includes instructions on how to handle the packet and any subsequent packets belonging to the same flow. This allows the OpenFlow switch to process subsequent packets belonging to the flow without involving the OpenFlow controller.

[0006] In the event that multiple packets belonging to a flow arrive at the OpenFlow switch before the OpenFlow controller is able to program the flow entry in the OpenFlow switch, the OpenFlow switch may end up sending multiple Packet-In messages to the OpenFlow controller. These Packet-In messages may be redundant in the sense that they will each elicit the same response from the OpenFlow controller (e.g., programming of a particular flow entry in the OpenFlow switch). The redundant OpenFlow Packet-In messages may unnecessarily consume the valuable computing resources and bandwidth of the OpenFlow switch and the OpenFlow controller.

SUMMARY

[0007] A method is implemented by a data plane device in a Software Defined Networking (SDN) network for selectively transmitting Packet-In messages to a controller in the SDN network. The method avoids transmitting redundant Packet-In messages to the controller. The method includes generating a flow entry in a flow table, where the flow entry includes a selective Packet-In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller, and where the selective Packet-In action instruction specifies a set of packet fields, receiving an incoming packet, where the incoming packet matches the flow entry in the flow table with the selective Packet-In action instruction, generating a Packet-In identifier (ID) based on a table ID of the flow table and a set of values in the incoming packet corresponding to the set of packet fields specified in the selective Packet-In action instruction, determining whether a Packet-In message associated with the Packet-In ID is being processed by the controller, and transmitting a Packet-In message for the incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is not being processed by the controller, where the Packet-In message transmitted to the controller includes the Packet-In ID.

[0008] A network device is configured to function as a data plane device in a Software Defined Networking (SDN) network for selectively transmitting Packet-In messages to a controller in the SDN network to avoid transmitting redundant Packet-In messages to the controller. The network device includes a set of one or more processors and a non-transitory machine-readable storage medium having stored therein a selective Packet-In component. The selective Packet-In component, when executed by the set of one or more processors, causes the network device to generate a flow entry in a flow table, where the flow entry includes a selective Packet-In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller, and where the selective Packet-In action instruction specifies a set of packet fields, receive an incoming packet, where the incoming packet matches the flow entry in the flow table with the selective Packet-In action instruction, generate a Packet-In identifier (ID) based on a table ID of the flow table and a set of values in the specified set of packet fields in the incoming packet, determine whether a Packet-In message associated with the Packet-In ID is being processed by the controller, and transmit a Packet-In message for the incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is not being processed by the controller, where the Packet-In message transmitted to the controller includes the Packet-In ID.

[0009] A non-transitory machine-readable medium has computer code stored therein, which when executed by a set of one or more processors of a network device functioning as a data plane device in a Software Defined Networking (SDN) network, causes the network device to perform operations for selectively transmitting Packet-In messages to a controller in the SDN network to avoid transmitting redundant Packet-In messages to the controller The operations include generating a flow entry in a flow table, where the flow entry includes a selective Packet- In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller, and where the selective Packet-In action instruction specifies a set of packet fields, receiving an incoming packet, where the incoming packet matches the flow entry in the flow table with the selective Packet-In action instruction, generating a Packet-In identifier (ID) based on a table ID of the flow table and a set of values in the incoming packet

corresponding to the set of packet fields specified in the selective Packet-In action instruction, determining whether a Packet-In message associated with the Packet-In ID is being processed by the controller, and transmitting a Packet-In message for the incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is not being processed by the controller, where the Packet-In message transmitted to the controller includes the Packet-In ID.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:

[0011] Fig. 1 is a block diagram of a switch that implements selective transmission of Packet- In messages, according to some embodiments.

[0012] Fig. 2 is a flow diagram of a process for selectively transmitting Packet-In messages, according to some embodiments.

[0013] Fig. 3 is a flow diagram of a process for processing a Packet-Out message, according to some embodiments.

[0014] Fig. 4 is a flow diagram of a process for responding to a Packet-In message, according to some embodiments.

[0015] Fig. 5 is a flow diagram of a generic process for selectively transmitting Packet-In messages, according to some embodiments. [0016] Fig. 6A illustrates connectivity between network devices (NDs) within an exemplary network, as well as three exemplary implementations of the NDs, according to some

embodiments.

[0017] Fig. 6B illustrates an exemplary way to implement a special-purpose network device, according to some embodiments.

[0018] Fig. 6C illustrates various exemplary ways in which virtual network elements (VNEs) may be coupled, according to some embodiments.

[0019] Fig. 6D illustrates a network with a single network element (NE) on each of the NDs, and within this straight forward approach contrasts a traditional distributed approach (commonly used by traditional routers) with a centralized approach for maintaining reachability and forwarding information (also called network control), according to some embodiments.

[0020] Fig. 6E illustrates the simple case of where each of the NDs implements a single NE, but a centralized control plane has abstracted multiple of the NEs in different NDs into (to represent) a single NE in one of the virtual network(s), according to some embodiments.

[0021] Fig. 6F illustrates a case where multiple VNEs are implemented on different NDs and are coupled to each other, and where a centralized control plane has abstracted these multiple VNEs such that they appear as a single VNE within one of the virtual networks, according to some embodiments.

[0022] Fig. 7 illustrates a general purpose control plane device with centralized control plane (CCP) software, according to some embodiments.

DETAILED DESCRIPTION

[0023] The following description describes methods and apparatus for selectively transmitting Packet- In messages to a controller in a Software Defined Networking (SDN) network. In the following description, numerous specific details such as logic implementations, opcodes, means to specify operands, resource partitioning/sharing/duplication implementations, types and interrelationships of system components, and logic partitioning/integration choices are set forth in order to provide a more thorough understanding of the present invention. It will be appreciated, however, by one skilled in the art that the invention may be practiced without such specific details. In other instances, control structures, gate level circuits and full software instruction sequences have not been shown in detail in order not to obscure the invention. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.

[0024] References in the specification to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0025] Bracketed text and blocks with dashed borders (e.g., large dashes, small dashes, dot- dash, and dots) may be used herein to illustrate optional operations that add additional features to embodiments of the invention. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments of the invention.

[0026] In the following description and claims, the terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. "Coupled" is used to indicate that two or more elements, which may or may not be in direct physical or electrical contact with each other, co-operate or interact with each other. "Connected" is used to indicate the establishment of communication between two or more elements that are coupled with each other.

[0027] An electronic device stores and transmits (internally and/or with other electronic devices over a network) code (which is composed of software instructions and which is sometimes referred to as computer program code or a computer program) and/or data using machine-readable media (also called computer-readable media), such as machine-readable storage media (e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory) and machine-readable transmission media (also called a carrier) (e.g., electrical, optical, radio, acoustical or other form of propagated signals - such as carrier waves, infrared signals). Thus, an electronic device (e.g., a computer) includes hardware and software, such as a set of one or more processors coupled to one or more machine-readable storage media to store code for execution on the set of processors and/or to store data. For instance, an electronic device may include non-volatile memory containing the code since the non- volatile memory can persist code/data even when the electronic device is turned off (when power is removed), and while the electronic device is turned on that part of the code that is to be executed by the processor(s) of that electronic device is typically copied from the slower nonvolatile memory into volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM)) of that electronic device. Typical electronic devices also include a set or one or more physical network interface(s) to establish network connections (to transmit and/or receive code and/or data using propagating signals) with other electronic devices. One or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware.

[0028] A network device (ND) is an electronic device that communicatively interconnects other electronic devices on the network (e.g., other network devices, end-user devices). Some network devices are "multiple services network devices" that provide support for multiple networking functions (e.g., routing, bridging, switching, Layer 2 aggregation, session border control, Quality of Service, and/or subscriber management), and/or provide support for multiple application services (e.g., data, voice, and video).

[0029] OpenFlow is a protocol that enables controllers and switches in an SDN network to communicate with each other. OpenFlow enables dynamic programming of flow control policies in the network. An OpenFlow channel is used to exchange OpenFlow messages between an OpenFlow switch and an OpenFlow controller.

[0030] For sake of illustration, embodiments are primarily described in a context where OpenFlow is used as the southbound protocol between a controller and a switch in an SDN network. However, it should be understood that the techniques described herein are applicable to other southbound protocols. As used herein, a "Packet-In message" refers to any type of message that is used to transfer control of a packet from a switch to a controller, and unless stated otherwise, is not limited to an OpenFlow Packet-In message. Similarly, as used herein, the term "Packet-Out message" refers to any type of message that is used to transfer control of a packet from a controller to a switch, and unless stated otherwise, is not limited to an OpenFlow Packet-Out message.

[0031] A switch uses a Packet-In message to transfer control of a packet to a controller (colloquially referred to as "punting" the packet to the controller). The switch may punt a packet to the controller via a Packet-In message, for example, if the switch does not know how to process the packet. A controller typically responds to a Packet-In message by programming a flow entry in the switch, which includes instructions on how to handle the packet and any subsequent packets belonging to the same flow. This allows the switch to process subsequent packets belonging to the same flow without involving the controller.

[0032] For example, in a network that implements Media Access Control (MAC) learning, whenever a packet with a new source MAC address arrives at a switch, the switch may punt the packet to the controller via a Packet-In message. In response, the controller may program a flow entry in the switch for handling subsequent packets that have the source MAC address as a destination address.

[0033] As another example, in a network that implements Network Address Translation (NAT), whenever the first packet belonging to a flow arrives at a switch, the switch may punt the packet to the controller via a Packet- In message. In response, the controller may program a flow entry in the switch for performing NAT on subsequent packets belonging to the flow (e.g., in forward and reverse directions).

[0034] As yet another example, in a network that implements Address Resolution Protocol (ARP), whenever a packet with a new destination IP address arrives at the switch, the switch may punt the packet to the controller via a Packet- In message. In response, the controller may program a flow entry in the switch for performing address resolution for subsequent packets with the same destination IP address.

[0035] In the event that multiple packets belonging to a flow arrive at the switch before the controller is able to process the Packet- In message (and before the controller is able to program a flow entry in the switch), the switch may end up transmitting multiple Packet-In messages to the controller (e.g., each packet may cause the switch to transmit a Packet-In message to the controller). These Packet-In messages may be redundant in the sense that they will each elicit the same response from the controller (e.g., programming of a particular flow entry in the switch). The redundant Packet-In messages may unnecessarily consume the valuable computing resources and bandwidth of the switch and the controller.

[0036] Embodiments described herein provide a technique for a switch to selectively transmit Packet-In messages to a controller in order to avoid transmitting redundant Packet-In messages to the controller. The controller typically knows which flow entries in the switch include packet punting actions and which fields of a packet are relevant for determining how the packet is to be processed at the switch. As such, the controller may know that packets having the same values in particular fields will elicit the same response from the controller (e.g., will result in the controller programming the same flow entry in the switch). Based on this, in one embodiment, the controller programs a flow table in the switch with a flow entry that includes a selective Packet-In action instruction that instructs the switch to selectively transmit Packet-In messages to the controller. In one embodiment, the selective Packet-In action instruction specifies the set of packet fields (e.g., packet header fields) that are to be used by the switch to determine which packets, when punted to the controller via a Packet-In message, will elicit the same response from the controller (and thus would be redundant). When the switch receives a packet that matches the flow entry with the selective Packet-In action instruction, the switch generates a Packet-In identifier (ID) based on the table ID of the flow table and the set of values in the packet corresponding to the set of packet fields specified in the selective Packet-In action instruction. The set of packet fields are configured such that the Packet-In ID will be the same for Packet-In messages that elicit the same response from the controller. The switch then determines whether a Packet-In message associated with the Packet-In ID is (already) being processed by the controller. If the switch determines that a Packet-In message associated with the Packet-In ID is not being processed by the controller, the switch transmits a Packet-In message for the packet to the controller. The Packet-In message for the packet includes the Packet-In ID (and this Packet-In message is said to be associated with the Packet-In ID) and may also include the packet itself or a portion thereof. If the switch determines that a Packet-In message associated with the Packet-In ID is already being processed by the controller, the switch refrains from transmitting a Packet-In message for the packet to the controller. In one embodiment, if a response from the controller is needed to further process the packet, the switch inserts the packet in a queue associated with the Packet-In ID. Subsequently, the switch may receive a Packet-Out message from the controller that includes the Packet-In ID and a set of packet processing instructions. The switch then processes each packet in the queue associated with the Packet-In ID according to the set of packet processing instructions. In this way, the switch selectively transmits Packet-In messages to the controller in a manner that avoids transmitting redundant Packet-In messages to the controller. Embodiments are further described herein with reference to the accompanying figures.

[0037] Fig. 1 is a block diagram of a switch that implements selective transmission of Packet- In messages, according to some embodiments. As shown, the switch 100 is communicatively coupled to a controller 110. In one embodiment, the switch 100 is a data plane device in a Software Defined Networking (SDN) network such as an OpenFlow switch and the controller 110 is a control plane device in an SDN network such as an OpenFlow controller. The switch 100 and the controller 110 may communicate over a south bound interface using OpenFlow or other suitable south bound protocol. The switch 100 includes a packet processing pipeline 115 that includes flow tables 120A-Z. Each flow table may include one or more flow entries 130. For example, flow table 120A includes flow entries 130A-Z. Each flow entry may include a packet matching criteria and a set of instructions to apply to packets matching the packet matching criteria. In one embodiment, the switch 100 generates flow entries 130 based on instructions received from the controller 110. It should be understood that the packet processing pipeline 115 can include more or less flow tables 120 and flow entries 130 than illustrated in the diagram.

[0038] The controller 110 manages the switch 100 and typically knows which fields of a packet are relevant for determining how a packet is to be processed at the switch. As such, the controller 110 may know that packets having the same values in particular fields, when punted to the controller 110, will elicit the same response from the controller 110. For example, the controller 110 may know that ARP request packets having the same destination IP address, when punted to the controller 110, will result in the controller programming the same flow entry 130 in the switch 100. As such, when multiple ARP request packets having the same destination IP address arrive at the switch 100, the switch 100 need not punt all of these packets to the controller 110. Rather, only one packet per destination IP address can be punted to the controller.

[0039] Embodiments avoid transmitting redundant Packet-In messages to the controller 110 by introducing a selective Packet-In action instruction that instructs the switch 100 to selectively transmit Packet-In messages to the controller 110. For example, flow entry 130Z includes a packet matching criteria that matches ARP packets and a selective Packet-In action instruction that instructs the switch 100 to selectively transmit Packet-In messages to the controller 110. The selective Packet-In action instruction specifies the set of packet fields (e.g., packet header fields) that are to be used by the switch to determine which packets, when punted to the controller via a Packet-In message, will elicit the same response from the controller (and thus would be redundant). In this example, the selective Packet-In action instruction specifies the destination IP address field (dest_IP) as the set of packet fields. For sake of illustration, in this example, the set of packet fields only includes a single packet field. It should be understood that the set of packet fields can include more than one packet field.

[0040] When the switch 100 receives an ARP request packet with its destination IP address field set to 1.1.1.1 (PKTl), the switch 100 determines that PKTl matches flow entry 130Z (since it is an ARP request packet). As such, the switch 100 executes the selective Packet-In action instruction in flow entry 130Z. The switch does this by generating a Packet-In identifier (ID) based on the table ID of flow table 120A and the value in the destination IP address field of PKTl, which in this example is 1.1.1.1. In one embodiment, the Packet-In ID is generated as a hash of these values. Since the set of packet fields specified in the selective Packet-In action instruction is the destination IP address field, the same Packet-In ID will be generated for ARP request packets having the same destination IP address. The switch 100 then determines whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110. In this example, PKTl is the first ARP request packet with destination IP address field set to 1.1.1.1, and thus the switch 100 determines that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110. The switch 100 thus transmits a Packet-In message for PKTl to the controller 110 (PKTl is punted to the controller 110). The switch 100 includes the Packet-In ID in the Packet-In message (and this Packet-In message is said to be associated with the Packet-In ID). In one embodiment, in conjunction with transmitting the Packet-In message associated with the Packet-In ID to the controller 110, the switch 100 stores an indication that a Packet-In message associated with the Packet- In ID is being processed by the controller 110. The switch 100 then creates an empty queue associated with the Packet-In ID (queue 140A in this example).

[0041] Before the switch 100 receives a corresponding Packet- Out message from the controller 110, the switch 100 may subsequently receive another ARP request packet with destination IP address field set to 1.1.1.1 (PKT2). Similar to PKT1 discussed above, PKT2 also matches flow entry 130Z (since it is also an ARP request packet), and thus the switch executes the selective Packet-In action instruction in flow entry 130Z. Similar to the operations described with reference to PKT1, the switch 100 generates a Packet-In ID based on the table ID of table 120A and the value in the destination IP address field of PKT2, which in this example is also 1.1.1.1. It should be noted that since this Packet-In ID is generated based on the same table ID and destination IP address, this Packet-In ID is the same as the Packet-In ID that was generated with relation to PKT1.

[0042] Since the switch 100 previously transmitted a Packet-In message associated with the Packet-In ID to the controller 110, the switch 100 determines that a Packet-In message associated with the Packet-In ID is being processed by the controller 110. The switch 100 may determine that a Packet-In message associated with the Packet-In ID is being processed by the controller 110 based on a previously stored indication or based on the existence of a queue associated with the Packet-In ID (e.g., existence of queue 140A). In this example, since a Packet-In message associated with the Packet-In ID is being processed by the controller 110, the switch 100 refrains from transmitting a Packet-In message for PKT2 to the controller 110. The switch 100 instead inserts PKT2 in the queue associated with the Packet-In ID (queue 140A in this example).

[0043] Subsequently, the switch 100 may receive an ARP request packet with its destination IP address field set to 2.2.2.2 (PKT3). This packet will match flow entry 130Z, and thus the switch 100 executes the selective Packet-In action instruction in flow entry 130Z. Thus, the switch 100 generates a Packet-In ID based on the table ID of table 120A and the value in the destination IP address field of PKT3, which in this example is 2.2.2.2. It should be noted that since this Packet-In ID is generated based on a different destination IP address than the destination IP address included in PKT1 and PKT2, this Packet-In ID will be different from the Packet-In ID that was generated with relation to PKT1 and PKT2. Since PKT3 is the first ARP request packet with destination IP address field set to 2.2.2.2, the switch 100 determines that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110. The switch 100 thus transmits a Packet-In message for PKT3 to the controller 110 (PKT3 is punted to the controller 110). The switch 100 includes the Packet-In ID in the Packet-In message for PKT3. The switch 100 then creates an empty queue associated with the Packet-In ID (queue 140B in this example).

[0044] The switch 100 may then receive another ARP request packet with its destination IP address field set to 2.2.2.2 (PKT4). Following similar operations as described above, the switch 100 determines that a Packet-In message for PKT4 need not be transmitted to the controller 110. Thus, the switch 100 refrains from transmitting a Packet-In message for PKT4 to the controller 110 and instead inserts PKT4 in queue 140B.

[0045] The switch may then receive multiple ARP request packets with destination IP address field set to 3.3.3.3 (PKT5, PKT6, and PKT7). Following similar operations as described above, the switch 100 only transmits a Packet-In message for PKT5 to the controller 110 (PKT5 is punted to the controller 110) and refrains from transmitting a Packet-In message for PKT6 and PKT7 to the controller 110. Instead, PKT6 and PKT7 are inserted in queue HOC. Thus, with the selective Packet-In action instruction illustrated in this example, the switch 100 only transmits a single Packet-In message to the controller 110 per destination IP address (for ARP request packets).

[0046] In response to receiving a Packet-In message associated with a Packet-In ID, the controller 110 may generate and transmit a corresponding Packet-Out message to the switch 100. The Packet-Out message may include the Packet-In ID (that was included in the corresponding Packet-In message) and a set of packet processing instructions. For example, in response to receiving the Packet-In message for PKT1, the controller 110 may generate and transmit a corresponding Packet-Out message to the switch 100, where the Packet-Out message includes the Packet-In ID generated in connection with PKT1 and a set of packet processing instructions for processing PKT1. When the switch 100 receives this Packet-Out message, the switch 100 processes each packet in the queue associated with the Packet-In ID (e.g., queue 140A in this example) according to the set of packet processing instructions. Thus, both PKT1 and PKT2 (which is stored in queue 140A) are processed according to the set of packet processing instructions included in the Packet-Out message. Once all of the packets in queue 140A are processed, the switch 100 can delete the queue 140A. The packets in the other queues 140B, HOC can also be processed in a similar fashion by a corresponding Packet-Out message for the queue (e.g., a Packet-Out message that includes the Packet-In ID associated with the queue 140).

[0047] There are some use cases where selective transmission of Packet-In messages is beneficial (e.g., in order to avoid transmitting redundant Packet-In messages), but where the switch 100 does not need to receive a corresponding Packet-Out message in order to further process a packet. For example, in a MAC learning use case, it may be desirable to only transmit one packet per source MAC address to the controller 110 so that the controller 110 can program the reverse path for the source MAC address in the switch 100. However, there is no need for queuing the packet, as the switch 100 can continue processing the packet (in the forward direction) without intervention from the controller 110.

[0048] An exemplary message structure for a Selective Packet-In action instruction is provided below:

/^Message structure for selective Packet-In action instruction*/

struct ofp_action_selective_packet_in {

uintl6_t type; /* OFPAT_OUTPUT. */

uintl6_t len; /* Length is 8. */

uintl6_t port; /* CONTROLLER */

uint8_t oxm_fields[0]; /* 0 or more OXM match fields */

uintl6_t max_len; /* Max length to send to controller; A value of

OFPCML_NO_BUFFER, when OXM fields are present, indicates that the switch needs to send only one Packet-In message to controller. Subsequent Packet-In messages should be suppressed. */

} ;

[0049] The type field may be set to a value of OFPAT_OUTPUT and the port field may be set to a value of CONTROLLER to indicate that the packet is to be output to the controller 110 (e.g., punted to the controller 110). The oxm_fields field can be used to specify the set of packet fields that the switch 100 is to use to determine which packets, when punted to the controller 110 via a Packet-In message, will elicit the same response from the controller 110. When an output to controller action specifies at least one packet field in the oxm_fields field, this may indicate that Packet-In messages are to be selectively transmitted to the controller 110. The max_len field may be set to a value of OFPCML_NO_BUFFER to indicate that queueing is not enabled. The max_len field may be set to a different value to indicate that queuing is enabled.

[0050] A controller 110 may program a flow entry 130 in a switch 100 that includes a selective Packet-In action instruction. In one embodiment, before the controller 110 programs such a flow entry 130 in the switch 100, the controller 110 needs to be informed that the switch 100 supports the selective Packet-In action feature. In OpenFlow, when a controller 110 and a switch 100 establish a connection, the controller 110 typically transmits an

OFPT_FEATURES_REQUEST message to the switch 100 requesting that the switch 100 identify capabilities/features supported by the switch 100. The switch 100 then responds to the controller 110 with an OFPT_FEATURES_REPLY message that identifies the

capabilities/features supported by the switch 100. However, as of OpenFlow 1.3, only certain capabilities/features are included as part of the OFPT_FEATURES_REPLY message, as defined by ofp_capabilities. In one embodiment, OpenFlow can be extended so that the controller 110 can be informed of additional capabilities/features supported by the switch 100 (e.g., vendor- specific capabilities). In one embodiment, the controller 110 transmits a

VENDOR_TYPE_SWITCH_FEATURES_REQUEST message to the switch 100 requesting that the switch 100 identify additional capabilities/features supported by the switch 100. The switch 100 then responds to the controller 110 with a

VENDOR_TYPE_SWITCH_FEATURES_REPLY message identifying additional

capabilities/features supported by the switch 100. In one embodiment, if the switch 100 supports the selective Packet-In action feature, the

VENDOR_TYPE_SWITCH_FEATURES_REPLY message includes an indication that the switch 100 supports the selective Packet-In action feature. Upon determining that the switch 100 supports the selective Packet-In action feature, the controller 110 may program a flow entry 130 in the switch 100 that includes a selective Packet-In action instruction (e.g., by transmitting an OFPT_FLOW_MOD message to the switch, where the OFPT_FLOW_MOD message includes a packet matching criteria (e.g., match field) and a selective Packet-In action instruction).

[0051] For example, the following exemplary message structures can be used by the controller 110 and the switch 100 to exchange capability information:

Capabilities Flag:

enum vendor_specific_switch_features_capabilities flags {

SELECTIVE_PACKET_IN = 1 « 1

} ;

VENDOR_TYPE_SWITCH_FEATURES_REQUEST:

/* Experimenter extension. */

/* For Vendor Type Switch Features Request, send expjype is

VENDOR_TYPE_SWITCH_FEATURES_REQUEST */

struct ofp_experimenter_header {

struct ofpjieader header; /* Type OFPT_EXPERIMENTER. */

uint32_t experimenter; /* Experimenter ID:

* - MSB 0: low-order bytes are IEEE OUI.

* - MSB != 0: defined by ONF. */

uint32_t expjype; /* Experimenter defined. */ /* Experimenter-defined arbitrary additional data. */

} ;

OFP_ASSERT(sizeof(struct ofp_experimenter_header) == 16);

VENDOR_TYPE_SWITCH_FEATURES_PvESPONSE:

struct vendor_switch_features_response {

struct ofp_experimenter_header exp_header; /* exp_type is

VENDOR_TYPE_SWITCH_FEATURES_RESPONSE */ uint64_t datapath_id; /* Datapath unique ID.*/

uint32_t length; /* length of exp_capabilities in bytes */

uint8_t pad[4]; /* Align to 64 bits */

/* Followed by length bytes containing the capabilities data */

uint8_t exp_capabilities[0]; /* Bitmap of support

"vendor_switch_features_capabilities". */

} ;

OFP_ASSERT(sizeof(struct vendor_switch_features_response) == 32); Common Header:

/* All messages in this extension use the following message header */

/* Common header for all messages */

struct vendor_header {

struct ofpjieader header; /* OFPT_EXPERIMENTER. */

uint32_t experimenter; /* VENDOR_EXPERIMENTER_ID. */

uint32_t exp_type; /* One of MSG_TYPE_* above. */

} ;

OFP_ASSERT(sizeof(struct vendor_header) == sizeof(struct ofp_experimenter_header));

[0052] An advantage of selectively transmitting Packet-In messages to a controller 110 is that it avoids transmitting redundant Packet-In messages to the controller 110, which results in less bandwidth consumption between the switch 100 and the controller 110 and also reduces the processing load at the controller 110. Yet another advantage is that latency is improved for queued packets since they do not have to be transmitted to the controller 110 via a Packet-In message and transmitted back to the switch 100 via a Packet-Out message in order to be processed. Rather, queued packets are processed locally at the switch 100 when the switch 100 receives a Packet-Out message for the first packet in the queue 140. Yet another advantage is that the set of packet fields in the selective Packet-In action instruction can be configured as desired. For example, for ARP use cases, the set of packet fields in the selective Packet-In action instruction can be set to specify the destination IP address field so that only one packet per destination IP address is punted to the controller 110. As another example, for MAC learning use cases, the set of packet fields in the selective Packet-In action instruction can be set to specify the source MAC address field so that only one packet per source MAC address is punted to the controller 110. Other advantages will be readily apparent from the descriptions provided herein.

[0053] Fig. 2 is a flow diagram of a process for selectively transmitting Packet-In messages, according to some embodiments. In one embodiment, the process is implemented by a switch 100 (or other data plane device) in an SDN network, where the switch 100 is communicatively coupled to a controller 110 in the SDN network. The operations in the flow diagrams will be described with reference to the exemplary embodiments of the other figures. However, it should be understood that the operations of the flow diagrams can be performed by embodiments of the invention other than those discussed with reference to the other figures, and the embodiments of the invention discussed with reference to these other figures can perform operations different than those discussed with reference to the flow diagrams.

[0054] In one embodiment, the process is initiated when the switch 100 receives an incoming packet (block 205). The switch 100 determines whether to selectively transmit a Packet-In message for the incoming packet (decision block 210). The switch 100 may determine to selectively transmit a Packet-In message for the incoming packet, for example, if the incoming packet matches a flow entry 130 that includes a selective Packet-In action instruction. The selective Packet-In action instruction may specify a set of packet fields that the switch 100 is to use to determine which packets, when punted to the controller 110 via a Packet-In message, will elicit the same response from the controller 110. If the switch 100 determines not to selectively transmit a Packet-In message for the incoming packet, the switch 100 continues with normal packet processing for the packet (block 215). Otherwise, if the switch 100 determines to selectively transmit a Packet-In message for the incoming packet, the switch 100 generates a Packet-In ID based on the table ID of the flow table 120 (in which the incoming packet matched) and the set of values in the incoming packet corresponding to the set of packet fields specified in the selective Packet-In action instruction in the flow entry (block 220).

[0055] The switch 100 then determines whether queuing is enabled (decision block 225). In one embodiment, the switch 100 determines whether queuing is enabled based on an indication in the selective Packet-In action instruction. For example, with reference to the selective Packet-In action instruction message structure described above, if the max_len field in the selective Packet-In action instruction is set to a value of OFPCML_NO_BUFFER, this may indicate that queueing is not enabled. A different value in the max_len field may indicate that queueing is enabled. If the switch 100 determines that queuing is enabled, the switch 100 then determines whether a queue 140 associated with the Packet-In ID exists (decision block 230). In an embodiment where queuing is enabled, if a queue 140 associated with the Packet-In ID exists, then this indicates that a Packet-In message associated with the Packet-In ID is being processed by the controller 110. As such, the switch 100 inserts the incoming packet in that queue 140 (block 235) and refrains from transmitting a Packet-In message for the incoming packet to the controller 110 (block 240).

[0056] In an embodiment where queuing is enabled, if a queue 140 associated with the Packet- In ID does not exist, then this indicates that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110. The switch 100 creates a queue 140 associated with the Packet-In ID (block 245) and transmits a Packet-In message for the incoming packet to the controller 110, where the Packet-In message includes the Packet-In ID (block 255).

[0057] Returning to decision block 225, if the switch 100 determines that queuing is not enabled, the switch 100 determines whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110 (decision block 260). The switch 100 may have previously stored an indication of whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110 and the switch 100 may determine whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110 based on such indication. If the switch 100 determines that a Packet-In message associated with the Packet-In ID is being processed by the controller 110, the switch 100 refrains from transmitting a Packet- In message for the incoming packet to the controller 110 (block 265) and continues with normal packet processing (block 270). Returning to decision block 260, if the switch 100 determines that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110, then the switch 100 transmits a Packet-In message for the incoming packet to the controller 110 (block 275) and stores an indication that a Packet-In message associated with the Packet-In ID is being processed by the controller 110 (block 280). The switch 100 then continues with normal packet processing (block 270).

[0058] Fig. 3 is a flow diagram of a process for processing a Packet-Out message, according to some embodiments. In one embodiment, the operations of the flow diagram may be performed by a switch 100 in an SDN network, where the switch 100 is communicatively coupled to a controller 110 in the SDN network.

[0059] In one embodiment, the process is initiated when the switch 100 receives a Packet-Out message (e.g., from the controller 110), where the Packet-Out message includes a Packet-In ID and a set of packet processing instructions (block 310). In one embodiment, the set of packet processing instructions include an instruction to generate a flow entry 130. If queuing is enabled, the switch 100 may have previously inserted one or more packets in a queue 140 associated with the Packet-In ID (e.g., as a result of the operations described with reference to Fig. 2). In response to receiving the Packet-Out message, the switch 100 processes packets in the queue 140 associated with the Packet-In ID according to the set of packet processing instructions in the Packet-Out message (block 320). In one embodiment, once the packets in the queue 140 have been processed, the switch 100 may delete the queue 140 (block 330). In one embodiment, if the switch 100 had previously stored an indication that a Packet-In message associated with the Packet-In ID is being processed by the controller 110, the switch 100 may now remove that indication.

[0060] Fig. 4 is a flow diagram of a process for processing a Packet-In message, according to some embodiments. In one embodiment, the operations of the flow diagram may be performed by a controller 110 in an SDN network, where the controller 110 is communicatively coupled to a switch 100 in the SDN network.

[0061] In one embodiment, the process is initiated when the controller 110 receives a Packet- In message (e.g., from the switch 100) (block 410). The Packet-In message may include a Packet-In ID and a packet that is being punted to the controller 110 (or a portion thereof). The controller 110 may respond to the Packet-In message by generating a Packet-Out message (block 420). The Packet-Out message may include packet processing instructions regarding how to process the packet at the switch 100 (e.g., an instruction to generate a flow entry 130) or other instructions. The controller 110 determines whether the Packet-In message includes a Packet-In ID (decision block 430). If the Packet-In message does not include a Packet-In ID, then this indicates that the Packet-In message is a normal Packet-In message (not a selectively transmitted Packet-In message). In this case, the controller 110 transmits the Packet-Out message to the switch 100 (block 450). Otherwise, if the Packet-In message includes a Packet- In ID, then the controller 110 adds the Packet-In ID to the Packet-Out message (block 440) before transmitting the Packet-Out message to the switch 100 (block 450).

[0062] Fig. 5 is a flow diagram of a generic process for selectively transmitting Packet-In messages to a controller, according to some embodiments. In one embodiment, the operations of the flow diagram may be performed by a data plane device (e.g., switch 100) in an SDN network. The data plane device may be communicatively coupled to a control plane device (e.g., controller 110) in the SDN network.

[0063] In one embodiment, the process is initiated when the data plane device generates a flow entry 130 in a flow table 120, where the flow entry 130 includes a selective Packet-In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller 110 (block 510). The selective Packet-In action instruction may specify a set of packet fields (e.g., the set of packet fields that the switch 100 is to use to determine which packets, when punted to the controller 110 via a Packet-In message, will elicit the same response from the controller 110). In one embodiment, the selective Packet-In action instruction includes an indication of whether queuing is enabled.

[0064] The data plane device then receives an incoming packet (block 520). The data plane device determines whether the incoming packet matches the flow entry 130 in the flow table 120 (decision block 530). If the data plane device determines that the incoming packet does not match the flow entry 130 in the flow table 120, the data plane device may match the incoming packet against other flow entries 130 in the flow table 120 or other flow tables 120 (block 540).

[0065] If the data plane device determines that the incoming packet matches the flow entry 130 in the flow table 120, the data plane device generates a Packet-In ID based on a table ID of the flow table 120 and a set of values in the incoming packet corresponding to the set of packet fields specified in the selective Packet-In action instruction (block 550).

[0066] The data plane device then determines whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110 (decision block 560). In one embodiment, the data plane device determines whether a Packet-In message associated with the Packet-In ID is being processed by the controller 110 based on a determination of whether a queue 140 associated with the Packet-In ID exists. For example, if a queue 140 associated with the Packet- In ID exists, then this indicates that a Packet-In message associated with the Packet-In ID is being processed by the controller 110. However, if a queue 140 associated with the Packet-In ID does not exist, then this indicates that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110.

[0067] If the data plane device determines that a Packet-In message associated with the Packet-In ID is not being processed by the controller 110, then the data plane device transmits a Packet-In message for the incoming packet to the controller 110 (block 580). The Packet-In message includes the Packet-In ID (as well as the incoming packet or a portion thereof). In one embodiment, upon transmitting the Packet-In message for the incoming packet to the controller 110, the data plane device stores an indication that a Packet-In message associated with the Packet-In ID is being processed by the controller 110. In an embodiment where queuing is enabled, if the data plane device determines that a Packet-In message associated with the Packet- In ID is not being processed by the controller 110 (e.g., because a queue 140 associated with the Packet-In ID does not exist), the data plane device creates the queue associated with the Packet- In ID. [0068] Returning to decision block 560, if the data plane device determines that a Packet-In message associated with the Packet-In ID is being processed by the controller 110, then the data plane device refrains from transmitting a Packet-In message for the incoming packet to the controller 110. In an embodiment where queuing is enabled, the data plane device may insert the incoming packet in a queue 140 associated with the Packet-In ID (without transmitting a Packet-In message for the incoming packet to the controller 110) (block 570). In an

embodiment where queueing is not enabled, the data plane device may process the incoming packet (e.g., forward the incoming packet towards its destination) without transmitting the Packet-In message for the incoming packet to the controller 110.

[0069] In one embodiment, the data plane device implements a timeout mechanism for a queue 140. For example, in one embodiment, the data plane device deletes the incoming packet from the queue 140 associated with the Packet-In ID in response to a determination that an elapsed lifetime of the incoming packet in the queue 140 exceeds a predetermined threshold timeout length. In one embodiment, the data plane device retransmits the Packet-In message for the incoming packet to the controller 110 one or more times before deleting the incoming packet from the queue.

[0070] After transmitting the Packet-In message to the controller 110, the data plane device may receive a Packet-Out message from the controller 110, where the Packet-Out message includes the Packet-in ID and a set of packet processing instructions. In an embodiment where queuing is enabled, in response to receiving the Packet-Out message, the data plane device may process each packet in the queue 140 associated with the Packet-In ID according to the set of packet processing instructions.

[0071] Fig. 6A illustrates connectivity between network devices (NDs) within an exemplary network, as well as three exemplary implementations of the NDs, according to some

embodiments of the invention. Fig. 6A shows NDs 600A-H, and their connectivity by way of lines between 600A-600B, 600B-600C, 600C-600D, 600D-600E, 600E-600F, 600F-600G, and 600A-600G, as well as between 600H and each of 600A, 600C, 600D, and 600G. These NDs are physical devices, and the connectivity between these NDs can be wireless or wired (often referred to as a link). An additional line extending from NDs 600A, 600E, and 600F illustrates that these NDs act as ingress and egress points for the network (and thus, these NDs are sometimes referred to as edge NDs; while the other NDs may be called core NDs).

[0072] Two of the exemplary ND implementations in Fig. 6A are: 1) a special-purpose network device 602 that uses custom application-specific integrated-circuits (ASICs) and a special-purpose operating system (OS); and 2) a general purpose network device 604 that uses common off-the-shelf (COTS) processors and a standard OS. [0073] The special-purpose network device 602 includes networking hardware 610 comprising compute resource(s) 612 (which typically include a set of one or more processors), forwarding resource(s) 614 (which typically include one or more ASICs and/or network processors), and physical network interfaces (NIs) 616 (sometimes called physical ports), as well as non- transitory machine readable storage media 618 having stored therein networking software 620. A physical NI is hardware in a ND through which a network connection (e.g., wirelessly through a wireless network interface controller (WNIC) or through plugging in a cable to a physical port connected to a network interface controller (NIC)) is made, such as those shown by the connectivity between NDs 600A-H. During operation, the networking software 620 may be executed by the networking hardware 610 to instantiate a set of one or more networking software instance(s) 622. Each of the networking software instance(s) 622, and that part of the networking hardware 610 that executes that network software instance (be it hardware dedicated to that networking software instance and/or time slices of hardware temporally shared by that networking software instance with others of the networking software instance(s) 622), form a separate virtual network element 630A-R. Each of the virtual network element(s) (VNEs) 630A-R includes a control communication and configuration module 632A-R (sometimes referred to as a local control module or control communication module) and forwarding table(s) 634A-R, such that a given virtual network element (e.g., 630A) includes the control

communication and configuration module (e.g., 632A), a set of one or more forwarding table(s) (e.g., 634A), and that portion of the networking hardware 610 that executes the virtual network element (e.g., 630A).

[0074] Software 620 can include code such as selective Packet-In component 625, which when executed by networking hardware 610, causes the special-purpose network device 602 to perform operations of one or more embodiments of the present invention as part networking software instances 622 (control path loop detection instance 635A).

[0075] The special-purpose network device 602 is often physically and/or logically considered to include: 1) a ND control plane 624 (sometimes referred to as a control plane) comprising the compute resource(s) 612 that execute the control communication and configuration module(s) 632A-R; and 2) a ND forwarding plane 626 (sometimes referred to as a forwarding plane, a data plane, or a media plane) comprising the forwarding resource(s) 614 that utilize the forwarding table(s) 634A-R and the physical NIs 616. By way of example, where the ND is a router (or is implementing routing functionality), the ND control plane 624 (the compute resource(s) 612 executing the control communication and configuration module(s) 632A-R) is typically responsible for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) and storing that routing information in the forwarding table(s) 634A-R, and the ND forwarding plane 626 is responsible for receiving that data on the physical NIs 616 and forwarding that data out the appropriate ones of the physical NIs 616 based on the forwarding table(s) 634A-R.

[0076] Fig. 6B illustrates an exemplary way to implement the special-purpose network device 602 according to some embodiments of the invention. Fig. 6B shows a special-purpose network device including cards 638 (typically hot pluggable). While in some embodiments the cards 638 are of two types (one or more that operate as the ND forwarding plane 626 (sometimes called line cards), and one or more that operate to implement the ND control plane 624 (sometimes called control cards)), alternative embodiments may combine functionality onto a single card and/or include additional card types (e.g., one additional type of card is called a service card, resource card, or multi-application card). A service card can provide specialized processing (e.g., Layer 4 to Layer 7 services (e.g., firewall, Internet Protocol Security (IPsec), Secure Sockets Layer (SSL) / Transport Layer Security (TLS), Intrusion Detection System (IDS), peer- to-peer (P2P), Voice over IP (VoIP) Session Border Controller, Mobile Wireless Gateways (Gateway General Packet Radio Service (GPRS) Support Node (GGSN), Evolved Packet Core (EPC) Gateway)). By way of example, a service card may be used to terminate IPsec tunnels and execute the attendant authentication and encryption algorithms. These cards are coupled together through one or more interconnect mechanisms illustrated as backplane 636 (e.g., a first full mesh coupling the line cards and a second full mesh coupling all of the cards).

[0077] Returning to Fig. 6A, the general purpose network device 604 includes hardware 640 comprising a set of one or more processor(s) 642 (which are often COTS processors) and network interface controller(s) 644 (NICs; also known as network interface cards) (which include physical NIs 646), as well as non-transitory machine readable storage media 648 having stored therein software 650. During operation, the processor(s) 642 execute the software 650 to instantiate one or more sets of one or more applications 664A-R. While one embodiment does not implement virtualization, alternative embodiments may use different forms of virtualization. For example, in one such alternative embodiment the virtualization layer 654 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 662A-R called software containers that may each be used to execute one (or more) of the sets of applications 664A-R; where the multiple software containers (also called virtualization engines, virtual private servers, or jails) are user spaces (typically a virtual memory space) that are separate from each other and separate from the kernel space in which the operating system is run: and where the set of applications running in a given user space, unless explicitly allowed, cannot access the memory of the other processes. In another such alternative embodiment the virtualization layer 654 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and each of the sets of applications 664A-R is run on top of a guest operating system within an instance 662A-R called a virtual machine (which may in some cases be considered a tightly isolated form of software container) that is run on top of the hypervisor - the guest operating system and application may not know they are running on a virtual machine as opposed to running on a "bare metal" host electronic device, or through para-virtualization the operating system and/or application may be aware of the presence of virtualization for optimization purposes. In yet other alternative embodiments, one, some or all of the

applications are implemented as unikernel(s), which can be generated by compiling directly with, an application only a limited set of libraries (e.g., from a library operating system (LibOS) including drivers libraries of OS services) that provide the particular OS services needed by the application. As a unikernel can be implemented to run directly on hardware 640, directly on a hypervisor (in which case the unikernel is sometimes described as running within a LibOS virtual machine), or in a software container, embodiments can be implemented fully with unikernels running directly on a hypervisor represented by virtualization layer 654, unikernels running within software containers represented by instances 662A-R, or as a combination of unikernels and the above-described techniques (e.g., unikernels and virtual machines both run directly on a hypervisor, unikernels and sets of applications that are run in different software containers).

[0078] The instantiation of the one or more sets of one or more applications 664A-R, as well as virtualization if implemented, are collectively referred to as software instance(s) 652. Each set of applications 664A-R, corresponding virtualization construct (e.g., instance 662A-R) if implemented, and that part of the hardware 640 that executes them (be it hardware dedicated to that execution and/or time slices of hardware temporally shared), forms a separate virtual network element(s) 660A-R.

[0079] The virtual network element(s) 660A-R perform similar functionality to the virtual network element(s) 630A-R - e.g., similar to the control communication and configuration module(s) 632A and forwarding table(s) 634A (this virtualization of the hardware 640 is sometimes referred to as network function virtualization (NFV)). Thus, NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which could be located in Data centers, NDs, and customer premise equipment (CPE). While embodiments of the invention are illustrated with each instance 662A-R corresponding to one VNE 660A-R, alternative embodiments may implement this correspondence at a finer level granularity (e.g., line card virtual machines virtualize line cards, control card virtual machine virtualize control cards, etc.); it should be understood that the techniques described herein with reference to a correspondence of instances 662A-R to VNEs also apply to embodiments where such a finer level of granularity and/or unikernels are used.

[0080] In certain embodiments, the virtualization layer 654 includes a virtual switch that provides similar forwarding services as a physical Ethernet switch. Specifically, this virtual switch forwards traffic between instances 662A-R and the NIC(s) 644, as well as optionally between the instances 662A-R; in addition, this virtual switch may enforce network isolation between the VNEs 660A-R that by policy are not permitted to communicate with each other (e.g., by honoring virtual local area networks (VLANs)).

[0081] Software 650 can include code such as selective Packet- In component 663, which when executed by processor(s) 642, cause the general purpose network device 604 to perform operations of one or more embodiments of the present invention as part software instances 662A-R.

[0082] The third exemplary ND implementation in Fig. 6A is a hybrid network device 606, which includes both custom ASICs/special-purpose OS and COTS processors/standard OS in a single ND or a single card within an ND. In certain embodiments of such a hybrid network device, a platform VM (i.e., a VM that that implements the functionality of the special-purpose network device 602) could provide for para-virtualization to the networking hardware present in the hybrid network device 606.

[0083] Regardless of the above exemplary implementations of an ND, when a single one of multiple VNEs implemented by an ND is being considered (e.g., only one of the VNEs is part of a given virtual network) or where only a single VNE is currently being implemented by an ND, the shortened term network element (NE) is sometimes used to refer to that VNE. Also in all of the above exemplary implementations, each of the VNEs (e.g., VNE(s) 630A-R, VNEs 660A-R, and those in the hybrid network device 606) receives data on the physical NIs (e.g., 616, 646) and forwards that data out the appropriate ones of the physical NIs (e.g., 616, 646). For example, a VNE implementing IP router functionality forwards IP packets on the basis of some of the IP header information in the IP packet; where IP header information includes source IP address, destination IP address, source port, destination port (where "source port" and

"destination port" refer herein to protocol ports, as opposed to physical ports of a ND), transport protocol (e.g., user datagram protocol (UDP), Transmission Control Protocol (TCP), and differentiated services code point (DSCP) values.

[0084] Fig. 6C illustrates various exemplary ways in which VNEs may be coupled according to some embodiments of the invention. Fig. 6C shows VNEs 670A.1-670A.P (and optionally VNEs 670A.Q-670A.R) implemented in ND 600A and VNE 670H.1 in ND 600H. In Fig. 6C, VNEs 670A.1-P are separate from each other in the sense that they can receive packets from outside ND 600A and forward packets outside of ND 600A; VNE 670A.1 is coupled with VNE 670H.1, and thus they communicate packets between their respective NDs; VNE 670A.2- 670A.3 may optionally forward packets between themselves without forwarding them outside of the ND 600A; and VNE 670A.P may optionally be the first in a chain of VNEs that includes VNE 670A.Q followed by VNE 670A.R (this is sometimes referred to as dynamic service chaining, where each of the VNEs in the series of VNEs provides a different service - e.g., one or more layer 4-7 network services). While Fig. 6C illustrates various exemplary relationships between the VNEs, alternative embodiments may support other relationships (e.g., more/fewer VNEs, more/fewer dynamic service chains, multiple different dynamic service chains with some common VNEs and some different VNEs).

[0085] The NDs of Fig. 6A, for example, may form part of the Internet or a private network; and other electronic devices (not shown; such as end user devices including workstations, laptops, netbooks, tablets, palm tops, mobile phones, smartphones, phablets, multimedia phones, Voice Over Internet Protocol (VOIP) phones, terminals, portable media players, GPS units, wearable devices, gaming systems, set-top boxes, Internet enabled household appliances) may be coupled to the network (directly or through other networks such as access networks) to communicate over the network (e.g., the Internet or virtual private networks (VPNs) overlaid on (e.g., tunneled through) the Internet) with each other (directly or through servers) and/or access content and/or services. Such content and/or services are typically provided by one or more servers (not shown) belonging to a service/content provider or one or more end user devices (not shown) participating in a peer-to-peer (P2P) service, and may include, for example, public webpages (e.g., free content, store fronts, search services), private webpages (e.g.,

username/password accessed webpages providing email services), and/or corporate networks over VPNs. For instance, end user devices may be coupled (e.g., through customer premise equipment coupled to an access network (wired or wirelessly)) to edge NDs, which are coupled (e.g., through one or more core NDs) to other edge NDs, which are coupled to electronic devices acting as servers. However, through compute and storage virtualization, one or more of the electronic devices operating as the NDs in Fig. 6A may also host one or more such servers (e.g., in the case of the general purpose network device 604, one or more of the software instances 662A-R may operate as servers; the same would be true for the hybrid network device 606; in the case of the special-purpose network device 602, one or more such servers could also be run on a virtualization layer executed by the compute resource(s) 612); in which case the servers are said to be co-located with the VNEs of that ND. [0086] A virtual network is a logical abstraction of a physical network (such as that in Fig. 6A) that provides network services (e.g., L2 and/or L3 services). A virtual network can be implemented as an overlay network (sometimes referred to as a network virtualization overlay) that provides network services (e.g., layer 2 (L2, data link layer) and/or layer 3 (L3, network layer) services) over an underlay network (e.g., an L3 network, such as an Internet Protocol (IP) network that uses tunnels (e.g., generic routing encapsulation (GRE), layer 2 tunneling protocol (L2TP), IPSec) to create the overlay network).

[0087] A network virtualization edge (NVE) sits at the edge of the underlay network and participates in implementing the network virtualization; the network-facing side of the NVE uses the underlay network to tunnel frames to and from other NVEs; the outward-facing side of the NVE sends and receives data to and from systems outside the network. A virtual network instance (VNI) is a specific instance of a virtual network on a NVE (e.g., a NE/VNE on an ND, a part of a NE/VNE on a ND where that NE/VNE is divided into multiple VNEs through emulation); one or more VNIs can be instantiated on an NVE (e.g., as different VNEs on an ND). A virtual access point (VAP) is a logical connection point on the NVE for connecting external systems to a virtual network; a VAP can be physical or virtual ports identified through logical interface identifiers (e.g., a VLAN ID).

[0088] Examples of network services include: 1) an Ethernet LAN emulation service (an Ethernet-based multipoint service similar to an Internet Engineering Task Force (IETF)

Multiprotocol Label Switching (MPLS) or Ethernet VPN (EVPN) service) in which external systems are interconnected across the network by a LAN environment over the underlay network (e.g., an NVE provides separate L2 VNIs (virtual switching instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network); and 2) a virtualized IP forwarding service (similar to IETF IP VPN (e.g., Border Gateway Protocol (BGP)/MPLS IP VPN) from a service definition perspective) in which external systems are interconnected across the network by an L3 environment over the underlay network (e.g., an NVE provides separate L3 VNIs (forwarding and routing instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network)). Network services may also include quality of service capabilities (e.g., traffic classification marking, traffic conditioning and scheduling), security capabilities (e.g., filters to protect customer premises from network - originated attacks, to avoid malformed route announcements), and management capabilities (e.g., full detection and processing).

[0089] Fig. 6D illustrates a network with a single network element on each of the NDs of Fig. 6A, and within this straight forward approach contrasts a traditional distributed approach (commonly used by traditional routers) with a centralized approach for maintaining reachability and forwarding information (also called network control), according to some embodiments of the invention. Specifically, Fig. 6D illustrates network elements (NEs) 670A-H with the same connectivity as the NDs 600A-H of Fig. 6A.

[0090] Fig. 6D illustrates that the distributed approach 672 distributes responsibility for generating the reachability and forwarding information across the NEs 670A-H; in other words, the process of neighbor discovery and topology discovery is distributed.

[0091] For example, where the special-purpose network device 602 is used, the control communication and configuration module(s) 632A-R of the ND control plane 624 typically include a reachability and forwarding information module to implement one or more routing protocols (e.g., an exterior gateway protocol such as Border Gateway Protocol (BGP), Interior Gateway Protocol(s) (IGP) (e.g., Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), Routing Information Protocol (RIP), Label Distribution Protocol (LDP), Resource Reservation Protocol (RSVP) (including RS VP-Traffic Engineering (TE): Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol Label Switching

(GMPLS) Signaling RSVP-TE)) that communicate with other NEs to exchange routes, and then selects those routes based on one or more routing metrics. Thus, the NEs 670A-H (e.g., the compute resource(s) 612 executing the control communication and configuration module(s) 632A-R) perform their responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by distributively determining the reachability within the network and calculating their respective forwarding information. Routes and adjacencies are stored in one or more routing structures (e.g., Routing Information Base (RIB), Label Information Base (LIB), one or more adjacency structures) on the ND control plane 624. The ND control plane 624 programs the ND forwarding plane 626 with information (e.g., adjacency and route information) based on the routing structure(s). For example, the ND control plane 624 programs the adjacency and route information into one or more forwarding table(s) 634A-R (e.g., Forwarding Information Base (FIB), Label Forwarding Information Base (LFIB), and one or more adjacency structures) on the ND forwarding plane 626. For layer 2 forwarding, the ND can store one or more bridging tables that are used to forward data based on the layer 2 information in that data. While the above example uses the special-purpose network device 602, the same distributed approach 672 can be implemented on the general purpose network device 604 and the hybrid network device 606.

[0092] Fig. 6D illustrates that a centralized approach 674 (also known as software defined networking (SDN)) that decouples the system that makes decisions about where traffic is sent from the underlying systems that forwards traffic to the selected destination. The illustrated centralized approach 674 has the responsibility for the generation of reachability and forwarding information in a centralized control plane 676 (sometimes referred to as a SDN control module, controller, network controller, OpenFlow controller, SDN controller, control plane node, network virtualization authority, or management control entity), and thus the process of neighbor discovery and topology discovery is centralized. The centralized control plane 676 has a south bound interface 682 with a data plane 680 (sometime referred to the infrastructure layer, network forwarding plane, or forwarding plane (which should not be confused with a ND forwarding plane)) that includes the NEs 670A-H (sometimes referred to as switches, forwarding elements, data plane elements, or nodes). The centralized control plane 676 includes a network controller 678, which includes a centralized reachability and forwarding information module 679 that determines the reachability within the network and distributes the forwarding information to the NEs 670A-H of the data plane 680 over the south bound interface 682 (which may use the OpenFlow protocol). Thus, the network intelligence is centralized in the centralized control plane 676 executing on electronic devices that are typically separate from the NDs. In one embodiment, the network controller 678 may include a selective Packet- In component 681 that when executed by the network controller 678, causes the network controller 678 to perform operations of one or more embodiments described herein above.

[0093] For example, where the special-purpose network device 602 is used in the data plane 680, each of the control communication and configuration module(s) 632A-R of the ND control plane 624 typically include a control agent that provides the VNE side of the south bound interface 682. In this case, the ND control plane 624 (the compute resource(s) 612 executing the control communication and configuration module(s) 632A-R) performs its responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) through the control agent communicating with the centralized control plane 676 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 679 (it should be understood that in some embodiments of the invention, the control

communication and configuration module(s) 632A-R, in addition to communicating with the centralized control plane 676, may also play some role in determining reachability and/or calculating forwarding information - albeit less so than in the case of a distributed approach; such embodiments are generally considered to fall under the centralized approach 674, but may also be considered a hybrid approach).

[0094] While the above example uses the special-purpose network device 602, the same centralized approach 674 can be implemented with the general purpose network device 604 (e.g., each of the VNE 660A-R performs its responsibility for controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by communicating with the centralized control plane 676 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 679; it should be understood that in some embodiments of the invention, the VNEs 660A-R, in addition to communicating with the centralized control plane 676, may also play some role in determining reachability and/or calculating forwarding information - albeit less so than in the case of a distributed approach) and the hybrid network device 606. In fact, the use of SDN techniques can enhance the NFV techniques typically used in the general purpose network device 604 or hybrid network device 606 implementations as NFV is able to support SDN by providing an infrastructure upon which the SDN software can be run, and NFV and SDN both aim to make use of commodity server hardware and physical switches.

[0095] Fig. 6D also shows that the centralized control plane 676 has a north bound interface 684 to an application layer 686, in which resides application(s) 688. The centralized control plane 676 has the ability to form virtual networks 692 (sometimes referred to as a logical forwarding plane, network services, or overlay networks (with the NEs 670A-H of the data plane 680 being the underlay network)) for the application(s) 688. Thus, the centralized control plane 676 maintains a global view of all NDs and configured NEs/VNEs, and it maps the virtual networks to the underlying NDs efficiently (including maintaining these mappings as the physical network changes either through hardware (ND, link, or ND component) failure, addition, or removal).

[0096] While Fig. 6D shows the distributed approach 672 separate from the centralized approach 674, the effort of network control may be distributed differently or the two combined in certain embodiments of the invention. For example: 1) embodiments may generally use the centralized approach (SDN) 674, but have certain functions delegated to the NEs (e.g., the distributed approach may be used to implement one or more of fault monitoring, performance monitoring, protection switching, and primitives for neighbor and/or topology discovery); or 2) embodiments of the invention may perform neighbor discovery and topology discovery via both the centralized control plane and the distributed protocols, and the results compared to raise exceptions where they do not agree. Such embodiments are generally considered to fall under the centralized approach 674, but may also be considered a hybrid approach.

[0097] While Fig. 6D illustrates the simple case where each of the NDs 600A-H implements a single NE 670A-H, it should be understood that the network control approaches described with reference to Fig. 6D also work for networks where one or more of the NDs 600A-H implement multiple VNEs (e.g., VNEs 630A-R, VNEs 660A-R, those in the hybrid network device 606). Alternatively or in addition, the network controller 678 may also emulate the implementation of multiple VNEs in a single ND. Specifically, instead of (or in addition to) implementing multiple VNEs in a single ND, the network controller 678 may present the implementation of a VNE/NE in a single ND as multiple VNEs in the virtual networks 692 (all in the same one of the virtual network(s) 692, each in different ones of the virtual network(s) 692, or some combination). For example, the network controller 678 may cause an ND to implement a single VNE (a NE) in the underlay network, and then logically divide up the resources of that NE within the centralized control plane 676 to present different VNEs in the virtual network(s) 692 (where these different VNEs in the overlay networks are sharing the resources of the single VNE/NE implementation on the ND in the underlay network).

[0098] On the other hand, Figs. 6E and 6F respectively illustrate exemplary abstractions of NEs and VNEs that the network controller 678 may present as part of different ones of the virtual networks 692. Fig. 6E illustrates the simple case of where each of the NDs 600A-H implements a single NE 670A-H (see Fig. 6D), but the centralized control plane 676 has abstracted multiple of the NEs in different NDs (the NEs 670A-C and G-H) into (to represent) a single NE 6701 in one of the virtual network(s) 692 of Fig. 6D, according to some embodiments of the invention. Fig. 6E shows that in this virtual network, the NE 6701 is coupled to NE 670D and 670F, which are both still coupled to NE 670E.

[0099] Fig. 6F illustrates a case where multiple VNEs (VNE 670A.1 and VNE 670H.1) are implemented on different NDs (ND 600 A and ND 600H) and are coupled to each other, and where the centralized control plane 676 has abstracted these multiple VNEs such that they appear as a single VNE 670T within one of the virtual networks 692 of Fig. 6D, according to some embodiments of the invention. Thus, the abstraction of a NE or VNE can span multiple NDs.

[00100] While some embodiments of the invention implement the centralized control plane 676 as a single entity (e.g., a single instance of software running on a single electronic device), alternative embodiments may spread the functionality across multiple entities for redundancy and/or scalability purposes (e.g., multiple instances of software running on different electronic devices).

[00101] Similar to the network device implementations, the electronic device(s) running the centralized control plane 676, and thus the network controller 678 including the centralized reachability and forwarding information module 679, may be implemented a variety of ways (e.g., a special purpose device, a general-purpose (e.g., COTS) device, or hybrid device). These electronic device(s) would similarly include compute resource(s), a set or one or more physical NICs, and a non-transitory machine-readable storage medium having stored thereon the centralized control plane software. For instance, Fig. 7 illustrates, a general purpose control plane device 704 including hardware 740 comprising a set of one or more processor(s) 742 (which are often COTS processors) and network interface controller(s) 744 (NICs; also known as network interface cards) (which include physical NIs 746), as well as non-transitory machine readable storage media 748 having stored therein centralized control plane (CCP) software 750 and a selective Packet-In component 751.

[00102] In embodiments that use compute virtualization, the processor(s) 742 typically execute software to instantiate a virtualization layer 754 (e.g., in one embodiment the virtualization layer 754 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 762A-R called software containers (representing separate user spaces and also called virtualization engines, virtual private servers, or jails) that may each be used to execute a set of one or more applications; in another embodiment the virtualization layer 754 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and an application is run on top of a guest operating system within an instance 762A-R called a virtual machine (which in some cases may be considered a tightly isolated form of software container) that is run by the hypervisor ; in another embodiment, an application is implemented as a unikernel, which can be generated by compiling directly with an application only a limited set of libraries (e.g., from a library operating system (LihOS) including drivers/libraries of OS services) that provide the particular OS services needed by the application, and the unikernel can run directly on hardware 740, directly on a hypervisor represented by virtualization layer 754 (in which case the unikernel is sometimes described as running within a LibOS virtual machine), or in a software container represented by one of instances 762A-R). Again, in embodiments where compute virtualization is used, during operation an instance of the CCP software 750 (illustrated as CCP instance 776A) is executed (e.g., within the instance 762A) on the virtualization layer 754. In embodiments where compute virtualization is not used, the CCP instance 776A is executed, as a unikernel or on top of a host operating system, on the "bare metal" general purpose control plane device 704. The instantiation of the CCP instance 776A, as well as the virtualization layer 754 and instances 762A-R if implemented, are collectively referred to as software instance(s) 752.

[00103] In some embodiments, the CCP instance 776A includes a network controller instance 778. The network controller instance 778 includes a centralized reachability and forwarding information module instance 779 (which is a middleware layer providing the context of the network controller 678 to the operating system and communicating with the various NEs), and an CCP application layer 780 (sometimes referred to as an application layer) over the middleware layer (providing the intelligence required for various network operations such as protocols, network situational awareness, and user - interfaces). At a more abstract level, this CCP application layer 780 within the centralized control plane 676 works with virtual network view(s) (logical view(s) of the network) and the middleware layer provides the conversion from the virtual networks to the physical view.

[00104] The selective Packet-In component 751 can be executed by hardware 740 to perform operations of one or more embodiments of the present invention as part of software instances 752.

[00105] The centralized control plane 676 transmits relevant messages to the data plane 680 based on CCP application layer 780 calculations and middleware layer mapping for each flow. A flow may be defined as a set of packets whose headers match a given pattern of bits; in this sense, traditional IP forwarding is also flow-based forwarding where the flows are defined by the destination IP address for example; however, in other implementations, the given pattern of bits used for a flow definition may include more fields (e.g., 10 or more) in the packet headers. Different NDs/NEs/VNEs of the data plane 680 may receive different messages, and thus different forwarding information. The data plane 680 processes these messages and programs the appropriate flow information and corresponding actions in the forwarding tables (sometime referred to as flow tables) of the appropriate NE/VNEs, and then the NEs/VNEs map incoming packets to flows represented in the forwarding tables and forward packets based on the matches in the forwarding tables.

[00106] Standards such as OpenFlow define the protocols used for the messages, as well as a model for processing the packets. The model for processing packets includes header parsing, packet classification, and making forwarding decisions. Header parsing describes how to interpret a packet based upon a well-known set of protocols. Some protocol fields are used to build a match structure (or key) that will be used in packet classification (e.g., a first key field could be a source media access control (MAC) address, and a second key field could be a destination MAC address).

[00107] Packet classification involves executing a lookup in memory to classify the packet by determining which entry (also referred to as a forwarding table entry or flow entry) in the forwarding tables best matches the packet based upon the match structure, or key, of the forwarding table entries. It is possible that many flows represented in the forwarding table entries can correspond/match to a packet; in this case the system is typically configured to determine one forwarding table entry from the many according to a defined scheme (e.g., selecting a first forwarding table entry that is matched). Forwarding table entries include both a specific set of match criteria (a set of values or wildcards, or an indication of what portions of a packet should be compared to a particular value/values/wildcards, as defined by the matching capabilities - for specific fields in the packet header, or for some other packet content), and a set of one or more actions for the data plane to take on receiving a matching packet. For example, an action may be to push a header onto the packet, for the packet using a particular port, flood the packet, or simply drop the packet. Thus, a forwarding table entry for IPv4/IPv6 packets with a particular transmission control protocol (TCP) destination port could contain an action specifying that these packets should be dropped.

[00108] Making forwarding decisions and performing actions occurs, based upon the forwarding table entry identified during packet classification, by executing the set of actions identified in the matched forwarding table entry on the packet.

[00109] However, when an unknown packet (for example, a "missed packet" or a "match- miss" as used in OpenFlow parlance) arrives at the data plane 680, the packet (or a subset of the packet header and content) is typically forwarded to the centralized control plane 676. The centralized control plane 676 will then program forwarding table entries into the data plane 680 to accommodate packets belonging to the flow of the unknown packet. Once a specific forwarding table entry has been programmed into the data plane 680 by the centralized control plane 676, the next packet with matching credentials will match that forwarding table entry and take the set of actions associated with that matched entry.

[00110] A network interface (NI) may be physical or virtual; and in the context of IP, an interface address is an IP address assigned to a NI, be it a physical NI or virtual NI. A virtual NI may be associated with a physical NI, with another virtual interface, or stand on its own (e.g., a loopback interface, a point-to-point protocol interface). A NI (physical or virtual) may be numbered (a NI with an IP address) or unnumbered (a NI without an IP address). A loopback interface (and its loopback address) is a specific type of virtual NI (and IP address) of a

NE/VNE (physical or virtual) often used for management purposes; where such an IP address is referred to as the nodal loopback address. The IP address(es) assigned to the NI(s) of a ND are referred to as IP addresses of that ND; at a more granular level, the IP address(es) assigned to NI(s) assigned to a NE/VNE implemented on a ND can be referred to as IP addresses of that NE/VNE.

[00111] Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of transactions on data bits within a computer memory. These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of transactions leading to a desired result. The transactions are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[00112] It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the above discussion, it is appreciated that throughout the description, discussions utilizing terms such as "processing" or "computing" or "calculating" or "determining" or "displaying" or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

[00113] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method transactions. The required structure for a variety of these systems will appear from the description above. In addition, embodiments of the present invention are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of embodiments of the invention as described herein.

[00114] An embodiment of the invention may be an article of manufacture in which a non- transitory machine-readable medium (such as microelectronic memory) has stored thereon instructions which program one or more data processing components (generically referred to here as a "processor") to perform the operations described above. In other embodiments, some of these operations might be performed by specific hardware components that contain hardwired logic (e.g., dedicated digital filter blocks and state machines). Those operations might alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[00115] In the foregoing specification, embodiments of the invention have been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense. [00116] Throughout the description, embodiments of the present invention have been presented through flow diagrams. It will be appreciated that the order of transactions and transactions described in these flow diagrams are only intended for illustrative purposes and not intended as a limitation of the present invention. One having ordinary skill in the art would recognize that variations can be made to the flow diagrams without departing from the broader spirit and scope of the invention as set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A method implemented by a data plane device in a Software Defined Networking (SDN) network for selectively transmitting Packet-In messages to a controller in the SDN network to avoid transmitting redundant Packet-In messages to the controller, the method

comprising:

generating (510) a flow entry in a flow table, wherein the flow entry includes a selective Packet-In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller, and wherein the selective Packet-In action instruction specifies a set of packet fields;

receiving (520) an incoming packet, wherein the incoming packet matches the flow entry in the flow table with the selective Packet-In action instruction;

generating (550) a Packet-In identifier (ID) based on a table ID of the flow table and a set of values in the incoming packet corresponding to the set of packet fields specified in the selective Packet-In action instruction;

determining (560) whether a Packet-In message associated with the Packet-In ID is being processed by the controller; and

transmitting (580) a Packet-In message for the incoming packet to the controller in

response to a determination that a Packet-In message associated with the Packet- In ID is not being processed by the controller, wherein the Packet-In message transmitted to the controller includes the Packet-In ID.

2. The method of claim 1, further comprising:

inserting (570) another incoming packet in a queue associated with the Packet-In ID without transmitting a Packet-In message for the another incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is being processed by the controller.

3. The method of claim 2, further comprising:

receiving (310) a Packet-Out message from the controller, wherein the Packet-Out

message includes the Packet-In ID and a set of packet processing instructions; and

processing (320) each packet in the queue associated with the Packet-In ID according to the set of packet processing instructions.

4. The method of claim 2, further comprising:

deleting the another incoming packet from the queue associated with the Packet-In ID in response to a determination that an elapsed lifetime of the another incoming packet in the queue exceeds a predetermined threshold timeout length.

5. The method of claim 4, further comprising:

retransmitting the Packet-In message for the incoming packet to the controller before deleting the another incoming packet from the queue.

6. The method of claim 2, wherein determining whether a Packet-In message associated with the Packet-In ID is being processed by the controller is based on a determination of whether a queue associated with the Packet-In ID exists.

7. The method of claim 6, further comprising:

creating the queue associated with the Packet-In ID in response to a determination that the queue associated with the Packet-In ID does not exist.

8. The method of claim 1, wherein the selective Packet-In action instruction includes an

indication that queuing is not enabled.

9. The method of claim 8, further comprising:

processing another incoming packet without transmitting a Packet-In message for the another incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is being processed by the controller.

10. The method of claim 8, further comprising:

upon transmitting the Packet-In message for the incoming packet to the controller,

storing an indication that a Packet-In message associated with the Packet-In ID is being processed by the controller.

11. The method of claim 1, wherein the flow entry in the flow table is generated in response to an instruction received from the controller to generate the flow entry in the flow table.

12. A network device configured to function as a data plane device in a Software Defined Networking (SDN) network for selectively transmitting Packet- In messages to a controller in the SDN network to avoid transmitting redundant Packet-In messages to the controller, the network device comprising:

a set of one or more processors (642); and

a non-transitory machine-readable storage medium (648) having stored therein a

selective Packet-In component (663), which when executed by the set of one or more processors, causes the network device to generate a flow entry in a flow table, wherein the flow entry includes a selective Packet-In action instruction that instructs the data plane device to selectively transmit Packet-In messages to the controller, and wherein the selective Packet-In action instruction specifies a set of packet fields, receive an incoming packet, wherein the incoming packet matches the flow entry in the flow table with the selective Packet-In action instruction, generate a Packet-In identifier (ID) based on a table ID of the flow table and a set of values in the specified set of packet fields in the incoming packet, determine whether a Packet-In message associated with the Packet-In ID is being processed by the controller, and transmit a Packet-In message for the incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is not being processed by the controller, wherein the Packet-In message transmitted to the controller includes the Packet-In ID.

13. The network device of claim 12, wherein the selective Packet-In component, when executed by the set of one or more processors, further causes the network device to insert another incoming packet in a queue associated with the Packet-In ID without transmitting a Packet- In message for the another incoming packet to the controller in response to a determination that a Packet-In message associated with the Packet-In ID is being processed by the controller.

14. The network device of claim 13, wherein the selective Packet-In component, when executed by the set of one or more processors, further causes the network device to receive a Packet- Out message from the controller, wherein the Packet-Out message includes the Packet-In ID and a set of packet processing instructions and process each packet in the queue associated with the Packet-In ID according to the set of packet processing instructions.

15. The network device of claim 12, wherein the selective Packet- In component, when executed by the set of one or more processors, further causes the network device to process another incoming packet without transmitting a Packet- In message for the another incoming packet to the controller in response to a determination that a Packet- In message associated with the Packet- In ID is being processed by the controller.

16. A non-transitory machine-readable medium having computer code stored therein, which when executed by a set of one or more processors of a network device functioning as a data plane device in a Software Defined Networking (SDN) network, causes the network device to perform operations for selectively transmitting Packet-In messages to a controller in the SDN network to avoid transmitting redundant Packet-In messages to the controller, the operations comprising:

17. The non-transitory machine-readable medium of claim 16, wherein the computer code, when executed by the set of one or more processors of the network device, causes the network device to perform further operations comprising:

18. The non-transitory machine-readable medium of claim 17, wherein the computer code, when executed by the set of one or more processors of the network device, causes the network device to perform further operations comprising:

19. The non-transitory machine-readable medium of claim 16, wherein the selective Packet-In action instruction includes an indication that queuing is not enabled.

20. The non-transitory machine-readable medium of claim 19, wherein the computer code, when executed by the set of one or more processors of the network device, causes the network device to perform further operations comprising: