CN110071874B - Method and system for realizing topology discovery link in cross-domain SDN network - Google Patents

Method and system for realizing topology discovery link in cross-domain SDN network Download PDF

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Publication number
CN110071874B
CN110071874B CN201810066419.5A CN201810066419A CN110071874B CN 110071874 B CN110071874 B CN 110071874B CN 201810066419 A CN201810066419 A CN 201810066419A CN 110071874 B CN110071874 B CN 110071874B
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message
link detection
layer sdn
network
layer
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CN110071874A (en
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赵杨旭峰
熊小勇
张永福
杨岚
庞俊英
吕屹
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Shanghai Layer Peak Network Technology Co ltd
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Shanghai Layer Peak Network Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/02—Topology update or discovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/02—Topology update or discovery
    • H04L45/04—Interdomain routing, e.g. hierarchical routing

Abstract

The invention discloses a method for realizing topology discovery link in a cross-domain SDN network, which comprises the following steps: the upper-layer SDN controller constructs a link detection message and sends the link detection message to a first network element NE through a Packet Out message, and the first NE sends the link detection message Out from a specified port to be detected in the Packet Out message; after receiving the link detection message, the first NE on the service path of the lower-layer SDN network matches a service forwarding flow table, encapsulates the link detection message in the service message, and then sends the service message to the next NE on the service path; the last NE on the service path decapsulates the service message to obtain a link detection message and sends the link detection message out; after receiving a link detection message sent by a lower SDN network, a second NE of the upper SDN network matches a link detection flow table and sends the link detection message to an upper SDN controller through a Packet In message; and the upper-layer SDN controller analyzes the Packet In message and confirms that a link exists between two NEs In the upper-layer SDN network.

Description

Method and system for realizing topology discovery link in cross-domain SDN network
Technical Field
The invention relates to a communication technology, in particular to a method for realizing topology discovery link in a cross-domain SDN network. The invention also relates to a system for realizing topology discovery link in the cross-domain SDN network.
Background
Sending a Packet Out message to an NE (network element) through a controller In an SDN (software defined network), wherein the message comprises messages of a specified protocol, the messages are forwarded to adjacent devices, the adjacent devices match the specified protocol number through an Openflow flow table, the messages are sent back to the controller through a Packet In message, and the controller analyzes the Packet In message so as to find the direct connection relation of the two devices. However, if two SDN networks exist at the same time, as shown in fig. 1, an SDN B network is borne on the SDN a network, the SDN a network is similar to a Link for the SDN B network, the SDN B network does not need to know the internal situation in the SDN a network, an original SDN network Link discovery mechanism cannot discover a Link between a ' and B ' in the SDN B network, and can only discover a Link between a ' of the SDN B network and a of the SDN a network, but for a cross-domain situation, the SDN a and the SDN B concurrently use the same set of controller, so the discovered data is unavailable.
Through a traditional SDN network topology discovery method, as shown In fig. 2, an SDN Controller2 constructs a link detection Packet of Port3 of NE3, sends the Packet to NE3 through Packet Out, receives the Packet by NE1 after being sent from Port3 of NE3, matches the Packet with a link detection flow table of NE1, sends the Packet to SDN Controller1 through Packet In, and does not send the Packet to NE4 finally. Therefore, SDN B network cannot discover Link between NE3 and NE4, but SDN Controller1 cannot process information In Packet In message received by SDN a network SDN Controller1, and SDN Controller1 does not know existence of NE 3.
The prior art cannot find topological links of cross-domain SDN networks.
Disclosure of Invention
The invention provides a method for realizing topology discovery link in a cross-domain SDN network, which aims to solve the problem that topology link cannot be discovered aiming at the cross-domain SDN network in the prior art.
The invention provides a method for realizing topology discovery link in a cross-domain SDN network, which comprises the following steps:
an upper-layer SDN controller constructs a link detection message and sends the link detection message to a first network element NE through a Packet Out message, and the first NE sends the link detection message Out from a port to be detected specified in the Packet Out message;
after receiving the link detection message from a port of an upper-layer SDN network, a first NE on a service path of a lower-layer SDN network matches a service forwarding flow table issued by a lower-layer SDN controller, encapsulates the link detection message in a service message, and then sends the service message to a next NE on the service path;
the last NE on the service path decapsulates the service message to obtain the link detection message, and sends the link detection message out from a port connected with an upper-layer SDN network;
after receiving the link detection message sent by the lower-layer SDN network from a message receiving port connected with the lower-layer SDN network, a second NE of the upper-layer SDN network matches a link detection flow table and sends the link detection message to an upper-layer SDN controller through a Packet In message;
and the upper-layer SDN controller analyzes the Packet In message and confirms that a link exists between two NEs In the upper-layer SDN network.
Preferably, the Packet Out message includes: the link detection message and the information of the port to be detected;
preferably, the Packet In message includes: the link detection message and the message receiving port information;
preferably, the link detection message at least includes the following information: a protocol number, a unique identifier of the first NE and port information to be detected.
Preferably, before the upper-layer SDN controller constructs a link detection packet, the method further includes:
the upper-layer SDN controller issues link detection flow tables to all NEs in an upper-layer SDN network;
the lower-layer SDN controller issues link detection flow tables to all NEs in a lower-layer SDN network;
the content of the link detection flow table at least comprises a matching specified protocol number;
and the lower-layer SDN controller calculates a service forwarding path required to be provided by the lower-layer SDN network and issues the corresponding service forwarding flow table to the NE on the path.
Preferably, the method further comprises the following steps:
and setting the priority of the service forwarding flow table to be higher than that of a link detection flow table, and when the link detection message enters a lower-layer SDN network and is encapsulated into a service message, preferentially forwarding the service message by the service forwarding flow table.
Preferably, the parsing, by the upper-layer SDN controller, the Packet In information to confirm that a link exists between two NEs In the upper-layer SDN network includes:
and the upper-layer SDN controller analyzes the Packet In information to obtain message receiving port information of the second NE, and the unique identifier of the first NE and the port information to be detected, which are contained In the link detection message, and confirms that a link exists between the port to be detected of the first NE and the message receiving port of the second NE In the upper-layer SDN network.
The invention also provides a system for realizing topology discovery chaining in a cross-domain SDN network, which comprises an upper-layer SDN network and an upper-layer SDN network, wherein the upper-layer SDN network comprises an upper-layer SDN controller and NE of the upper-layer SDN network, and the lower-layer SDN network comprises a lower-layer SDN controller and NE of the lower-layer SDN network, wherein:
the upper-layer SDN controller is used for constructing a link detection message and sending the link detection message to a first NE of an upper-layer SDN through a Packet Out message;
the first NE of the SDN network is used for sending the link detection message Out from a port to be detected specified in the Packet Out message;
the first NE on the service path of the lower-layer SDN network is configured to match the service forwarding flow table issued by the lower-layer SDN controller after receiving the link detection packet from the port connected to the upper-layer SDN network, encapsulate the link detection packet in the service packet, and then send the service packet to the next NE on the service path;
the last NE on the service path of the lower SDN network is used for de-encapsulating the service message to obtain the link detection message and sending the link detection message out from a port of the upper SDN network;
the second NE of the upper-layer SDN network is configured to match a link detection flow table after receiving the link detection Packet sent by the lower-layer SDN network from a Packet receiving port of the upper-layer SDN network, and send the link detection Packet to the upper-layer SDN controller through a Packet In message;
and the upper-layer SDN controller is further used for analyzing the received Packet In message and confirming that a link exists between two NEs In the upper-layer SDN network.
Preferably, the Packet Out message includes: the link detection message and the information of the port to be detected;
preferably, the Packet In message includes: the link detection message and the message receiving port information;
preferably, the link detection message at least includes the following information: a protocol number, a unique identifier of the first NE and port information to be detected.
Preferably, the upper layer SDN controller is further configured to issue a link detection flow table to all NEs in the upper layer SDN network;
preferably, the lower-layer SDN controller is configured to issue link detection flow tables to all NEs in the lower-layer SDN network; the network element is also used for calculating a forwarding path required to be provided by a lower network and issuing a service forwarding flow table to the NE on the path;
preferably, the content of the link check flow table at least includes a matching specified protocol number.
Preferably, the priority of the service forwarding flow table is set to be higher than that of the link detection flow table, and when the link detection packet enters the lower-layer SDN network and is encapsulated in a service packet of the lower-layer SDN network, the service packet is preferentially forwarded by the service forwarding flow table.
Preferably, the upper-layer SDN controller is further specifically configured to analyze the Packet In information to obtain message receiving port information of the second NE and the unique identifier of the first NE and the port information to be detected, which are included In the link detection message, and determine that a link exists between the port to be detected of the first NE and the message receiving port of the second NE In the upper-layer SDN network.
Compared with the prior art, the invention has the following advantages:
multi-layer SDN network superposition can be supported; the discovery of the lower layer SDN network link is not affected, and the internal link can still be normally discovered; when an upper-layer SDN network link is discovered, the lower-layer SDN network topology does not need to be perceived, and only the link inside the topology is discovered; the network can be divided according to the service or the client, the networks in different domains are not visible, the upper network does not need to care about the specific topological condition of the lower network, and the network can be flexibly expanded as long as the lower network provides the communication service.
Drawings
Fig. 1 is a schematic structural diagram of an existing cross-domain SDN network;
fig. 2 is a schematic structural diagram of a link discovery mechanism of an existing conventional SDN network;
fig. 3 is a schematic structural diagram of a conventional SDN link discovery process cross-domain network;
fig. 4 is a flowchart illustrating a method for implementing a topology link in a cross-domain SDN network according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a system for implementing topology link discovery in a cross-domain SDN network according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an underlying SDN network provided by an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an upper-layer SDN network and a lower-layer SDN network provided by an embodiment of the present invention;
fig. 8 is a schematic structural diagram of creating a traffic path in an underlying network according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of cross-domain SDN network topology link discovery provided by an embodiment of the present invention;
fig. 10 is a schematic structural diagram of a link discovered by an upper-layer SDN network according to an embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather construed as limited to the embodiments set forth herein.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto, and variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention.
The following are some of the terms of art to which the invention relates:
an SDN controller: the control unit interacts with the network element, and a single or a plurality of controllers form a control plane;
NE: network Element, Network function entity responsible for data forwarding, NE and link between NEs form forwarding plane of Network;
SDN, Software Defined Networking; the network virtualization implementation method is an implementation mode of network virtualization, and the core technology OpenFlow separates a control plane and a data plane of network equipment, so that the flexible control of network flow is realized, and the network becomes more intelligent as a pipeline.
Link Link: the ports of two different NEs are connected, and the connection relationship between the two NEs is realized.
The purpose to be achieved by the scheme is to enable an upper-layer SDN network to discover links between NEs, so that a link detection message needs to be forwarded In a lower-layer SDN network, but cannot be uploaded to a controller of the lower-layer SDN network by Packet In.
The embodiment of the present invention is illustrated by two NEs, but the present invention is not limited to the case of two NEs, and the case of multiple NEs is within the scope of the present invention.
The embodiment provides a method for implementing topology link discovery in a cross-domain SDN network, as shown in fig. 4, the method includes the following steps:
step S101, an upper-layer SDN controller constructs a link detection message and sends the link detection message to a first NE of an upper-layer SDN through a Packet Out message, and the first NE of the upper-layer SDN sends the link detection message Out from a specified port to be detected in the Packet Out;
the port to be detected is connected with a lower-layer SDN network.
Preferably, before step S101, the method further includes:
and the upper-layer SDN controller inquires a database and acquires the information of the NE to be detected in the upper-layer SDN network. The NE information at least comprises: unique identifier of NE and port information of NE.
After the upper-layer SDN controller acquires the related NE information, constructing a link detection message according to the acquired related NE information, wherein the link detection message at least comprises the following information: protocol number, a unique identifier of the NE to be detected and port information to be detected.
After constructing a link detection message, sending the link detection message to a first NE to be detected on an upper-layer SDN network, wherein the link detection message at least comprises the following information: a protocol number, a unique identifier of the first NE and port information to be detected of the first NE.
An upper-layer SDN controller inquires a database, acquires information of all NEs in an upper-layer SDN, constructs a link detection flow table, and sends the link detection flow table to the NEs in the upper-layer SDN network;
a lower-layer SDN controller inquires a database, acquires information of all NEs in a lower-layer SDN, constructs a link detection flow table, and sends the link detection flow table to the NEs in the lower-layer SDN network;
the content of the link detection flow table at least comprises a matching specified protocol number;
after the first NE on the upper-layer SDN network confirms that the type of the message is a link detection message through a protocol number, the link detection message is sent Out from a port to be detected specified in Packet Out;
wherein the Packet Out message at least includes: the link detection message and port information to be detected of the upper-layer SDN network;
the detection message at least comprises the following information: a protocol number, a unique identifier of the first NE and port information to be detected of the first NE.
Preferably, before S101, the method further includes:
multiple NEs in an upper-layer SDN network need to be communicated through a lower-layer SDN network. And the lower-layer SDN controller inquires a database of the lower-layer SDN controller to acquire all NE state information. The link information comprises at least link state information; preferably, link delay information may also be included. And calculating a service forwarding path required to be provided by the lower-layer SDN network by the lower-layer SDN controller through all the obtained link information and NE information. The calculation method may be a shortest path calculation method. And acquiring all NE information on the path according to the calculated path. And constructing a service forwarding flow table of the related NE on the path according to the NE information and the calculated structural information of the path. And the lower-layer SDN controller sends the constructed service forwarding flow table to the related NE, so that the related NE completes the forwarding of the service message.
Preferably, in the NE of the lower-layer SDN network, the priority of the service forwarding flow table is set to be higher than that of the link detection flow table, and when a link detection packet enters the lower-layer SDN network and is encapsulated as a service packet of the lower-layer SDN network, the service forwarding flow table is preferentially forwarded without being processed by the link detection flow table.
Preferably, the upper-layer SDN controller sends the link detection Packet to a first NE of the upper-layer SDN network through a Packet Out message of an OpenFlow protocol, and the first NE sends the link detection Packet Out from a specified port in the Packet Out.
The Packet Out message of the OpenFlow protocol is mainly used for matching a partial data Packet in an SDN network without adding a flow entry to an OpenFlow switch. There are many kinds of data packets in the SDN network, and the number of the data packets is so small (such as ARP, IGMP, etc.), that it is not necessary to specify the processing method of the data packets through the flow table entry. At this time, the SDN controller may use a Packet Out message to tell the OpenFlow switch how a certain Packet is to be handled. The Packet Out message includes at least a data field and an action field.
In step S101, the Packet Out message tells the first NE of the upper layer SDN network that the link detection Packet is sent from the port to be detected of the first NE of the upper layer SDN network. The link detection message is placed in a data field of Packet Out information, action sets specific port information for specific detection, and a first NE of an upper-layer SDN network operates the link detection message in the data field of the Packet Out according to the action field, so that the link detection message is sent Out from the specific port, namely, from a port to be detected of the first NE of the upper-layer SDN network.
Step S102, after a first NE on a service path of a lower-layer SDN network receives an upper-layer SDN network link detection message sent by an upper-layer SDN network from a port of the upper-layer SDN network, matching a service forwarding flow table issued by a lower-layer SDN controller, packaging the upper-layer SDN network link detection message into a lower-layer SDN network service message, and then sending the lower-layer SDN network service message to a next NE on the service path in the lower-layer SDN network;
the service path is a service forwarding path that needs to be provided by the lower-layer SDN network and is calculated by the lower-layer SDN controller before step S101. The service forwarding path has two or more NEs, including at least a first NE and a last NE on the service path.
And after the first NE on the service path of the lower SDN network receives the upper SDN network link detection message, packaging the upper SDN network link detection message in the service message of the lower SDN network. If the packet enters from a port of the upper-layer SDN network, the packet is regarded as a link detection packet and needs to be packaged in a service packet in the lower-layer SDN network for forwarding. The encapsulation of the service message in the lower-layer SDN network service message means that data of the service message is added to the head and the tail of the link detection message. The data of the service message comprises a message type, a message length, a check code and the like. In fact, the whole link detection message is encapsulated as the initial service data. After the link detection message is packaged in a service message of a lower-layer SDN network, the NE queries a service forwarding flow table configured for the link detection message by a lower-layer SDN controller, and packages the detection message in the service message and forwards the detection message to the next NE on a service path according to network configuration information in the service forwarding flow table; until it is forwarded to the last NE on the traffic path.
When the link detection message enters the lower-layer SDN network, what the lower-layer SDN network needs to complete is to transmit the link detection message in a transparent way, so that the link detection message can be transmitted to the other end (the last NE of the lower-layer SDN network) of the lower-layer SDN network, the link detection message is packaged in a service message in the lower-layer SDN network, instead of the link detection message, and forwards the service message according to the specified service path, and sends the service message to the next NE on the service path, and after the service message is sent to the last NE on the service path, the service message is decapsulated to obtain the link detection message, and then matching a link detection flow table, and sending the link detection flow table back to the upper-layer SDN network, thereby ensuring that the lower-layer SDN network cannot process the detection message of the upper-layer SDN network, namely completing the transparent transmission of the link detection message by the lower-layer SDN network.
The Openflow flow table has a priority configuration option, and when the attributes of a packet can be matched with multiple flow tables at the same time, the flow table with the highest priority takes effect. Therefore, the priority of the flow table for service forwarding needs to be set higher than that of the link detection flow table, and when a link detection message enters a lower-layer SDN network, the link detection message is preferentially forwarded by the service flow table and cannot be processed by the link detection flow table.
Step S103, the last NE on the service path of the lower-layer SDN network decapsulates the service message to obtain a link detection message, and sends the link detection message out from a port connected with the upper-layer SDN network;
if the forwarded next NE of the lower-layer SDN network is not the last NE in the service path, continuing to forward the service message to the next NE, and if the forwarded next NE of the lower-layer SDN network is the last NE in the path, decapsulating the service message of the lower-layer SDN network by the last NE of the lower-layer SDN network to obtain a link detection message, and sending the link detection message out from a port of an upper-layer SDN network;
because the lower-layer SDN network controller calculates the optimal transparent transmission path according to the link information of the lower-layer SDN network, and configures the flow table of the NE in the path. Therefore, the NE of the lower-layer SDN network can determine whether the NE is the last NE according to the service forwarding flow table configured by the lower-layer SDN controller.
And the last NE in the service path decapsulates the service message, removes the message header and the message tail of the service message in real time, acquires the data segment of the service message of the SDN network at the lower layer, and obtains a link detection message which is completely the same as the link detection message sent to the first NE by the SDN controller at the upper layer.
Step S104, after receiving a link detection message sent by a lower SDN network from a message receiving port connected with the lower SDN network, a second NE of the upper SDN network matches a link detection flow table and sends the link detection message to an upper SDN controller through Packet In information;
the Packet In information includes: the link detection message and the message receiving port information of the second NE.
The link detection message at least comprises the following information: a protocol number, a unique identifier of the first NE and port information to be detected. The OpenFlow Packet In message is mainly used when a part of data packets enter the OpenFlow switch and no related matching flow table can process the data packets, the OpenFlow switch does not know how to operate the data packets, and the OpenFlow switch encapsulates the data packets In Packet _ In and sends the Packet _ In to the SDN controller. The data contained in packet _ in may be of many types, with arp and icmp being the most common types. The Packet In message includes at least: a match field and a data field.
Step S104, matching a link detection flow table, and sending a link detection message to the upper layer SDN controller through a Packet In message, specifically, putting message receiving port information of a second NE of the upper layer SDN network In a match field of Packet _ In, putting a link detection message that needs to be sent to the controller through Packet In a data field of Packet _ In, and sending the Packet In message to the upper layer SDN controller.
Step S105, after receiving the Packet In message, the upper-layer SDN controller analyzes the Packet In message, and confirms that a link exists between two NEs In the upper-layer SDN network.
The upper-layer SDN controller receives and analyzes the Packet In message, message receiving port information of a second NE In the upper-layer SDN network is obtained from a match field of the Packet In message, information of a link detection message is obtained from a data field of the Packet In message, and if the link detection message contains a unique identifier of the first NE and port information to be detected, the link detection message is the link detection message of the first NE sent to the upper-layer SDN network by the upper-layer SDN controller; and confirming that a port to be detected of a first NE of the upper-layer SDN network is connected with a message receiving port of a second NE of the upper-layer SDN network. Although the Packet In information does not directly carry the unique identifier of the second NE of the upper-layer SDN network, since the Packet In information is sent to the upper-layer SDN controller by the second NE of the upper-layer SDN network, the upper-layer SDN controller knows that the Packet In information is the second NE of the upper-layer SDN network.
By adopting the method, the SDN network can be divided according to services or clients, the networks in different domains are not visible, the upper-layer SDN network does not need to care about the specific topology condition of the lower-layer SDN network, and the network can be flexibly expanded as long as the lower-layer SDN network provides the communication service.
To implement the method of the first embodiment, this embodiment provides a system for implementing topology link discovery across a domain SDN network, as shown in fig. 5, where the system includes:
the upper-layer SDN network comprises an upper-layer SDN controller and NEs of the upper-layer SDN network, the lower-layer SDN network comprises a lower-layer SDN controller and NEs of the lower-layer SDN network, the NEs of the upper-layer SDN network are multiple and at least comprise a first NE of the upper-layer SDN network and a second NE of the upper-layer SDN network, the NEs of the lower-layer SDN network are multiple and at least comprise a first NE of the lower-layer SDN network and a second NE of the lower-layer SDN network, and the upper-layer SDN network comprises:
the upper-layer SDN controller is used for constructing a link detection message and sending the link detection message to a first NE of an upper-layer SDN through a Packet Out message;
the first NE of the SDN network is used for sending the link detection message Out from a port to be detected specified in the Packet Out message;
the first NE on the service path of the lower-layer SDN network is configured to match the service forwarding flow table issued by the lower-layer SDN controller after receiving the link detection packet sent by the upper-layer SDN network from the port of the upper-layer SDN network, encapsulate the link detection packet in the service packet of the lower-layer SDN network, and then send the service packet to the next NE on the service path;
the last NE on the service path of the lower SDN network is used for de-encapsulating the service message to obtain a link detection message and sending the link detection message out from a port of the upper SDN network;
the second NE of the upper-layer SDN network is configured to match a link detection flow table after receiving the link detection Packet sent by the lower-layer SDN network from a Packet receiving port of the upper-layer SDN network, and send the link detection Packet to the upper-layer SDN controller through a Packet In message;
the upper-layer SDN controller is further configured to analyze a Packet In message received and sent by a second NE of the upper-layer SDN network, and determine that a link exists between two NEs In the upper-layer SDN network, that is, a link exists between the port to be detected of the first NE and the Packet detection port of the second NE In the upper-layer SDN network.
The Packet Out message at least comprises: the link detection message and the information of the port to be detected;
the Packet In message at least includes: and the link detects the message and receives port information of the message.
The link detection message at least comprises the following information: a protocol number, a unique identifier of the first NE and port information to be detected.
Preferably, the upper-layer SDN network controller is further configured to issue a link detection flow table to all NEs in the upper-layer SDN network;
the lower-layer SDN network controller is used for issuing link detection flow tables to all NEs in the lower-layer SDN network; the network element is also used for calculating a forwarding path required to be provided by a lower network and issuing a service forwarding flow table to the NE on the path;
the content of the link detection flow table at least comprises a matching specified protocol number.
Preferably, the priority of the service forwarding flow table is set to be higher than that of the link detection flow table, and when a link detection message enters a lower-layer SDN network and is encapsulated in a lower-layer SDN network service message, the link detection message is preferentially forwarded by the service forwarding flow table.
The upper-layer SDN controller is further specifically configured to analyze the Packet In information to obtain Packet receiving port information of a second NE of the upper-layer SDN network, a unique identifier of a first NE of the upper-layer SDN network and port information to be detected of the first NE of the upper-layer SDN network, which are included In the link detection message, and determine that a link exists between a port to be detected of the first NE of the upper-layer SDN network and a Packet receiving port of the second NE of the upper-layer SDN network.
By adopting the method and the system, when the link detection message enters the lower-layer SDN network, the message is converted into the service message in the lower-layer SDN network through encapsulation, but not the link detection message, so that the message can be forwarded according to the specified path, when the message is sent to the device on the other side of the upper-layer SDN network, the message is unpacked and converted back to the original upper-layer SDN network link detection message, and then the message is sent back to the upper-layer SDN network, thereby ensuring that the lower-layer SDN network cannot process the detection message of the upper-layer SDN network.
On the basis of the foregoing embodiments, this embodiment exemplifies a process of implementing topology discovery chaining in a cross-domain SDN network.
Fig. 6 is a schematic structural diagram of a lower-layer SDN network provided in an embodiment of the present invention, and as shown in fig. 6, the lower-layer SDN network has 3 NEs, namely NE1, NE2, and NE5, and is controlled by SDN Controller 1. An upper-layer SDN network needs to be constructed, as shown in fig. 7, an originally constructed lower-layer SDN network is called an sdna network, an upper-layer SDN network that needs components is called an sdnb network, two NEs, that is, NE3 and NE4, are in the SDN B network and managed by SDN Controller2, no line that can be directly connected exists between NE3 and NE4, a link needs to be provided based on the SDN a network, so that NE3 and NE4 communicate, and SDN Controller2 cannot manage NE1, NE2, and NE5 in the SDN network. As shown in fig. 7, Port3 to be detected of NE3 in SDN B network is connected to Port1 of NE1 in a network a, and packet receiving Port1 of NE4 in B network is connected to Port3 of NE2 in a network a.
First, a Controller SDN Controller1 of the SDN a network calculates a service path from Port1 of NE1 to Port3 of NE2 in the SDN a network, as shown in fig. 8, since NE1 and NE2 are directly connected, the calculated path is from Port3 of NE1 to Port1 of NE2, and Controller SDN Controller1 of the SDN a network issues a service forwarding flow table to NE1 and NE 2.
After the service forwarding flow table in the SDN a network is completely issued, the packet entering from Port1 of NE1 will match the service forwarding flow table, be encapsulated and forwarded to NE2, and then be forwarded from Port3 of NE2 after being decapsulated.
After the service path in the SDN a network is created, the Controller2 of the SDN B network may start to perform link detection, as shown in fig. 9, the SDN Controller2 constructs a link detection message of Port3 of NE3, and sends the link detection message to NE3 through Packet Out, the link detection message is forwarded from Port3 of the Port to be detected of NE3 to Port1 of NE1 of the SDN a network, and then matches a service forwarding flow table issued by a lower-layer SDN Controller, the link detection message is encapsulated in the service message, and is forwarded according to the service path created by the SDN a network, and is forwarded from NE1 to NE2, the service message is decapsulated by the SDN 2 to obtain a link detection message, and is forwarded from Port3 of NE2 to NE4 of the SDN B network, and the message receiving Port t1 of NE4 receives the link detection message, and the link detection message sent by the Controller2 to the NE3 is completely the same as the link detection message, and matches the link detection message on the link flow table 4 of the link detection message, and sending the link detection message to an SDN B network Controller2 through Packet In.
SDN B network Controller2 parses a link detection Packet In sent by NE4, and obtains that Port3 of NE3 and Port1 of NE4 In the SDN B network are connected, as shown In fig. 10, SDN B network does not sense existence of SDN a network, but considers that NE3 and NE4 are directly connected.
The purpose to be achieved by this embodiment is to enable the SDN B network to discover the Link between Port3 of NE3 and Port1 of NE4, so that a Link detection Packet of the SDN B network needs to be forwarded In the SDN a network, but is not uploaded to the Controller SDN Controller1 of the SDN a network by Packet In. The SDN network can be divided according to services or clients, networks in different domains are not visible, an upper-layer SDN B network does not need to care about the specific topology condition of a lower-layer SDN A network, the lower-layer SDN A network only needs to provide connectivity service, and the network can be expanded flexibly.
By adopting the method and the system, the superposition of multiple layers of SDN networks can be supported; the discovery of the lower layer SDN network link is not affected, and the internal link can still be normally discovered; when an upper-layer SDN network link is discovered, the lower-layer SDN network topology does not need to be perceived, and only the link inside the topology is discovered; the network can be divided according to the service or the client, the networks in different domains are not visible, the upper network does not need to care about the specific topological condition of the lower network, and the network can be flexibly expanded as long as the lower network provides the communication service.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto, and variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims (6)

1. A method for realizing topology discovery chaining in a cross-domain SDN network is characterized by comprising the following steps:
an upper-layer SDN controller constructs a link detection message and sends the link detection message to a first network element NE through a Packet Out message, and the first NE sends the link detection message Out from a port to be detected specified in the Packet Out message;
after receiving the link detection message from a port of an upper-layer SDN network, a first NE on a service path of a lower-layer SDN network matches a service forwarding flow table issued by a lower-layer SDN controller, encapsulates the link detection message in a service message, and then sends the service message to a next NE on the service path;
the last NE on the service path decapsulates the service message to obtain the link detection message, and sends the link detection message out from a port connected with an upper-layer SDN network;
after receiving the link detection message sent by the lower-layer SDN network from a message receiving port connected with the lower-layer SDN network, a second NE of the upper-layer SDN network matches a link detection flow table and sends the link detection message to an upper-layer SDN controller through a Packet In message;
the upper-layer SDN controller analyzes the Packet In message and confirms that a link exists between two NEs In the upper-layer SDN network;
the Packet Out message includes: the link detection message and the information of the port to be detected;
the Packet In message includes: the link detection message and the message receiving port information;
the link detection message at least comprises the following information: the protocol number, the unique identifier of the first NE and the information of the port to be detected;
before the upper-layer SDN controller constructs a link detection packet, the method further includes:
the upper-layer SDN controller issues link detection flow tables to all NEs in an upper-layer SDN network;
the lower-layer SDN controller issues link detection flow tables to all NEs in a lower-layer SDN network;
the content of the link detection flow table at least comprises a matching specified protocol number;
and the lower-layer SDN controller calculates a service forwarding path required to be provided by the lower-layer SDN network and issues the corresponding service forwarding flow table to the NE on the path.
2. The method of claim 1, further comprising:
and setting the priority of the service forwarding flow table to be higher than that of a link detection flow table, and when the link detection message enters a lower-layer SDN network and is encapsulated into a service message, preferentially forwarding the service message by the service forwarding flow table.
3. The method of claim 1, wherein the upper-layer SDN controller analyzes the Packet In information and confirms that a link exists between two NEs In an upper-layer SDN network, and specifically includes:
and the upper-layer SDN controller analyzes the Packet In information to obtain message receiving port information of the second NE, and the unique identifier of the first NE and the port information to be detected, which are contained In the link detection message, and confirms that a link exists between the port to be detected of the first NE and the message receiving port of the second NE In the upper-layer SDN network.
4. A system for realizing topology discovery chaining in a cross-domain SDN network is characterized by comprising an upper-layer SDN network and an upper-layer SDN network, wherein the upper-layer SDN network comprises an upper-layer SDN controller and NE (NEs) of the upper-layer SDN network, and the lower-layer SDN network comprises a lower-layer SDN controller and NE (NEs) of the lower-layer SDN network, wherein:
the upper-layer SDN controller is used for constructing a link detection message and sending the link detection message to a first NE of an upper-layer SDN through a Packet Out message;
the first NE of the SDN network is used for sending the link detection message Out from a port to be detected specified in the Packet Out message;
the first NE on the service path of the lower-layer SDN network is configured to match a service forwarding flow table issued by the lower-layer SDN controller after receiving the link detection packet from a port connected to the upper-layer SDN network, encapsulate the link detection packet in the service packet, and then send the service packet to the next NE on the service path;
the last NE on the service path of the lower SDN network is used for de-encapsulating the service message to obtain the link detection message and sending the link detection message out from a port of the upper SDN network;
the second NE of the upper-layer SDN network is configured to match a link detection flow table after receiving the link detection Packet sent by the lower-layer SDN network from a Packet receiving port of the upper-layer SDN network, and send the link detection Packet to the upper-layer SDN controller through a Packet In message;
the upper-layer SDN controller is further used for analyzing the received Packet In message and confirming that a link exists between two NEs In the upper-layer SDN network;
the Packet Out message includes: the link detection message and the information of the port to be detected;
the Packet In message includes: the link detection message and the message receiving port information;
the link detection message at least comprises the following information: the protocol number, the unique identifier of the first NE and the information of the port to be detected;
the upper-layer SDN controller is also used for issuing a link detection flow table to all NEs in the upper-layer SDN network;
the lower-layer SDN controller is used for issuing link detection flow tables to all NEs in the lower-layer SDN network; the network element is also used for calculating a forwarding path required to be provided by a lower network and issuing a service forwarding flow table to the NE on the path;
the content of the link detection flow table at least comprises a matching specified protocol number.
5. The system of claim 4, wherein:
the priority of the service forwarding flow table is set to be higher than that of the link detection flow table, and when the link detection message enters the lower-layer SDN network and is encapsulated in a service message of the lower-layer SDN network, the service message is preferentially forwarded by the service forwarding flow table.
6. The system of claim 4, wherein:
the upper-layer SDN controller is further specifically configured to analyze the Packet In information to obtain message receiving port information of the second NE and the unique identifier of the first NE and the port information to be detected, which are included In the link detection message, and determine that a link exists between the port to be detected of the first NE and the message receiving port of the second NE In the upper-layer SDN network.
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