WO2020087398A1

WO2020087398A1 - Method and apparatus for advertising and processing bier capability of link, and communication node

Info

Publication number: WO2020087398A1
Application number: PCT/CN2018/113183
Authority: WO
Inventors: Senthil DHANARAJ; Jingrong XIE
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-10-31
Filing date: 2018-10-31
Publication date: 2020-05-07
Also published as: CN113016165A; CN113016165B

Abstract

Provided are a method and an apparatus for advertising and processing BIER capability of link, and a communication node, where a first node receives a first packet from a second node, wherein the first packet comprises first capability information comprising one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the first, determines whether the one or more bits comprised in the first capability information support a BSL corresponding to an interface of the first node, wherein the interface of the first node corresponds to the first link, and establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding if the one or more bits comprised in the first capability information do not support the BSL corresponding to the interface of the first node, the technical solution of this embodiment can support the partial BIER capable nodes in the network without deploying the complicated IGP multi-topology technology.

Description

METHOD AND APPARATUS FOR ADVERTISING AND PROCESSING BIER CAPABILITY OF LINK, AND COMMUNICATION NODE

TECHNICAL FIELD

The present disclosure relates to the technical field of Bit Index Explicit Replication (BIER) technology, and in particular, to a method and an apparatus for advertising and processing BIER capability of a link, and a communication node.

BACKGROUND

In BIER technology, if a router advertises the BIER information by Interior Gateway Protocol (IGP) underlay, then the IGP router is considered to be “BIER capable router” or “BIER Forwarding Router (BFR) ” . If a router does not advertise the BIER information by IGP underlay, then the IGP router is considered to be “non-BIER capable router” or “non-BFR” .

However it is possible that, some BIER routers have a mix of line cards with some line cards support BIER and some line cards do not support BIER (as shown in FIG. 1) , where one router have many line cards, each line card have many interfaces, and an interface in the line card can be regarded as link. Such routers are called as “partial BIER capable router” or “partial BFR” . In a brown-field deployment of BIER (where the customer already using existing multicast technologies like Protocol Independent Multicast (PIM) , Multicast Label Distribution Protocol (MLDP) and Resource Reservation Protocol-Traffic Engineering (RSVP-TE) and intend to replace them with BIER to enjoy the advantages offered by BIER technology) , the network may contains a mix of “BIER capable” , “non-BIER capable” and “partial BIER capable” routers. Forwarding of multicast packets using the BIER header requires special hardware and hence the support for migration from existing multicast technologies (PIM, MLDP, and RSVP-TE) to BIER in brownfield deployments is very important.

Several methods have been proposed for supporting “non-BIER capable” routers, but some cannot support “partial BIER capable” routers, and some can support “partial BIER capable” routers by deploying multi-topology. However, the network operators agree to deploy multi-topology for the sake of supporting non-BIER capable routers is subjective. Besides, deploying multi-topology requires touching the Operations, Administrations and Management (OAM) or configuration of all the links in the network, and may lose the simplicity of single topological view for both unicast and multicast network.

This background information is provided to reveal information believed by the applicant to be of possible relevance to the present disclosure. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present disclosure.

SUMMARY

In view of the above, in order to overcome the above problem, the present disclosure provides a method and an apparatus for advertising and processing BIER capability of link, and communication node.

The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect the present disclosure relates to a method for processing BIER capability of link, where a first node receives a first packet from a second node, where the first packet includes first capability information including one or more bits, and each bit supports a Bit String Length (BSL) corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the first node, determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link, then establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node.

With the method for processing BIER capability of link provided in the present disclosure, the partial BIER capable nodes in the network can be supported without deploying the complicated IGP multi-topology. In a scenario encountering a partial BIER capable node in the network topology during traffic forwarding, the first node determines whether to forward the traffic to the partial BIER capable node or not based on the first capability information. The traffic can be forwarded even encountering a partial BIER capable node in the network topology.

In a first possible implementation form of the method according to the first aspect as such, the first packet further includes second capability information, the first node further determines whether the second capability information indicates the first link supports BIER forwarding if the one or more bits included in the first capability information support the BSL corresponding to the interface of the first node, and then establishes the tunnel between the first node and the third node if the second capability information indicates the first link does not support BIER forwarding.

The second capability information is also included in the first packet, the first node further determines whether the second capability information indicates the first link supports BIER forwarding. Then both the first capability information and the second capability information are considered for BIER forwarding. In a scenario encountering a partial BIER capable node in the network topology during traffic forwarding, the first node determines whether to forward the traffic to the partial BIER capable node or not based on both the first capability information and the second capability information. The traffic can be forwarded even encountering a partial BIER capable node in the network topology.

In a second possible implementation form of the method according to first possible implementation form of the method, the first node further adds the second node to a BIER shortest path tree (SPT) by using shortest path first (SPF) if the second capability information indicates the first link supports BIER forwarding.

In a scenario encountering a partial BIER capable node in the network topology during SPT building, the first node determines to add the second node to a BIER SPT by using SPF if the second capability information indicates the first link supports BIER forwarding. The traffic can be forwarded even encountering a partial BIER capable node in the network topology.

In a third possible implementation form of the method according to the first possible implementation form or the second possible implementation form of the method, where the first capability information and the second capability information are included in a sub-TLV of the first packet; if the first packet is an IGP Open Shortest Path First routing protocol (OSPF) Link State Advertisement (LSA) packet, the sub-TLV is included in OSPF Extended Link Opaque LSA under the OSPF Extended Link TLV.

In a fourth possible implementation form of the method according to the first possible implementation form or the second possible implementation form of the method, where the first capability information and the second capability information are included in a sub-TLV of the first packet; if the first packet is an IGP Intermediate System-Intermediate System routing protocol (ISIS) Link State Protocol (LSP) packet, the sub-TLV is included under TLV-22 of the first packet or TLV-23 of the first packet.

The third possible implementation form and the fourth possible implementation form show the first capability information and the second capability information can be carried under different TLV in different protocol, and the packet can be LSA or LSP packet, then the technical solution have better compatibility with the existing protocols.

According to a second aspect the present disclosure relates to a method for advertising BIER capability of link, where a second node determines first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and a first node; then advertises a first packet to a first node, where the first packet includes the first capability information.

With the method for advertising BIER capability of link provided in the present disclosure, the partial BIER capable nodes in the network can be supported without deploying the complicated IGP multi-topology technology.

In a first possible implementation form of the method according to the second aspect as such, the first packet further includes second capability information, where the second capability information is used for indicating the first link supports BIER forwarding, the second node further determines the second capability information and advertises the second capability information.

The second capability information is also indicated in the first data, which can be used for the first node further determines whether the second capability information indicates the first link supports BIER forwarding.

In a second possible implementation form of the method according to first possible implementation form of the method, where the first capability information and the second capability information are included in a sub-TLV of the first packet; if the first packet is an IGP OSPF LSA packet, the sub-TLV is included in OSPF Extended Link Opaque LSA under the OSPF Extended Link TLV.

In a third possible implementation form of the method according to first possible implementation form of the method, where the first capability information and the second capability information are included in a sub-TLV of the first packet; if the first packet is an IGP ISIS LSP packet, the sub-TLV is included under TLV-22 of the first packet or TLV-23 of the first packet.

The second possible implementation form and the third possible implementation form show the first capability information and the second capability information can be carried under different TLV in different protocol, and the packet can be LSA or LSP packet, then the technical solution have better compatibility with the existing protocols.

According to a third aspect the present disclosure relates to an apparatus for advertising BIER capability of link, the apparatus includes a receiving module, a first determining module and an establishing module, the receiving module is configured to receive a first packet from a second node, where the first packet includes first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the apparatus. The first determining module is configured to determine whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the apparatus, where the interface of the apparatus corresponds to the first link. The establishing module is configured to establish a tunnel between the apparatus and a third node to bypass the second node for BIER forwarding if the first determining module determines that the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the apparatus.

In a first possible implementation form of the apparatus according to the third aspect as such, where the first packet further includes second capability information, the first determining module is specifically configured to determine whether the second capability information indicates the first link supports BIER forwarding, if the first determining module determines that the one or more bits included in the first capability information support the BSL corresponding to the interface of the apparatus; the establishing module is specifically configured to establish the tunnel between the apparatus and the third node if the second capability information indicates the first link does not support BIER forwarding.

In a second possible implementation form of the apparatus according to first possible implementation form of the apparatus, the apparatus further includes an adding module, the adding module configured to add the second node to a BIER SPT by using SPF if the second capability information indicates the first link supports BIER forwarding.

According to a fourth aspect the present disclosure relates to an apparatus for advertising BIER capability of link, the apparatus includes a second determining module and an advertising module. The second determining module is configured to determine first capability information including one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the apparatus, and the interface of the apparatus corresponds to a first link between the apparatus and a first node. The advertising module is configured to advertise a first packet to a first node, where the first packet includes the first capability information.

In a first possible implementation form of the apparatus according to the fourth aspect as such, where the first packet further includes second capability information, where the second capability information is used for indicating the first link supports BIER forwarding; the second determining module is further configured to determine the second capability information; the advertising module is further configured to advertise the second capability information.

The method according to the first aspect of the present disclosure can be performed by the apparatus according to the third aspect of the present disclosure. The method according to the second aspect of the present disclosure can be performed by the apparatus according to the fourth aspect of the present disclosure. Further features and implementation forms of the method according to the first aspect of the present disclosure result directly from the functionality of the apparatus according to the third aspect of the present disclosure and its different implementation forms. Further features and implementation forms of the method according to the second aspect of the present disclosure result directly from the functionality of the apparatus according to the fourth aspect of the present disclosure and its different implementation forms.

According to a fifth aspect the present disclosure relates to an apparatus for processing BIER capability of link which includes a processor and a memory. The memory is storing instructions that cause the processor to perform the method according to the first aspect.

According to a sixth aspect the present disclosure relates to an apparatus for advertising BIER capability of link which includes a processor and a memory. The memory is storing instructions that cause the processor to perform the method according to the second aspect.

According to a seventh aspect, a computer-readable storage medium having stored thereon instructions that when executed cause one or more processors configured to process BIER capability of link is proposed. The instructions cause the one or more processors to perform a method according to the first aspect or any possible embodiment of the first aspect.

According to an eighth aspect, a computer-readable storage medium having stored thereon instructions that when executed cause one or more processors configured to advertise BIER capability of link is proposed. The instructions cause the one or more processors to perform a method according to the second aspect or any possible embodiment of the second aspect.

According to a ninth aspect the present disclosure relates to a first communication node including an apparatus for processing BIER capability of link according to the third or the fifth aspect.

According to a tenth aspect the present disclosure relates to a second communication node including an apparatus for advertising BIER capability of link according to the fourth or the sixth aspect.

The implementation and technical effect of the apparatus cited above can refer to the implementation and technical effect of the method cited above.

With the method or apparatus for advertising and processing BIER capability of link, the partial BIER capable nodes in the network can be supported without deploying the complicated IGP multi-topology technology.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are used to provide a further understanding of the present disclosure, constitute a part of the specification, and are used to explain the present disclosure together with the following specific embodiments, but should not be construed as limiting the present disclosure. In the drawings,

FIG. 1 is a schematic view of partial BIER capable router;

FIG. 2 is a schematic view of a first solution for supporting “non-BIER capable” nodes in prior art;

FIG. 3 is a schematic view of a second solution for supporting “non-BIER capable” nodes in prior art;

FIG. 4 is a schematic view of a third solution for supporting “non-BIER capable” nodes in prior art;

FIG. 5 is a schematic view of technical problems of the first solution in prior art;

FIG. 6 is a schematic view of technical problems of the second solution in prior art;

FIG. 7 is a schematic view of how partial BIER capable nodes can be supported by using multi-topology in prior art;

FIG. 8 is a schematic flowchart of a first method for advertising and processing BIER capability of link according to an embodiment of the present disclosure;

FIG. 9 is a schematic view of a sub-TLV according to an embodiment of the present disclosure;

FIG. 10 is a schematic view of an example application scenario according to an embodiment of the present disclosure;

FIG. 11 is a schematic flowchart of a second method for advertising and processing BIER capability of link according to an embodiment of the present disclosure;

FIG. 12 is a schematic view of another example application scenario according to an embodiment of the present disclosure;

FIG. 13 is a structural view of a first apparatus for processing BIER capability of link according to an embodiment of the present disclosure;

FIG. 14 is a structural view of a second apparatus for processing BIER capability of link according to an embodiment of the present disclosure;

FIG. 15 is a structural view of an apparatus for advertising BIER capability of link according to an embodiment of the present disclosure; and

FIG. 16 is a schematic diagram of a hardware device.

DESCRIPTION OF EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and include structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

For instance, it is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps) , even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units) , even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.

Bit Index Explicit Replication (BIER) is an architecture that provides optimal multicast forwarding through a “BIER domain” without requiring intermediate routers to maintain any multicast related per-flow state. In BIER architecture, each receiver is represented by a unique bit in the bitmask and all the intended multicast receivers are encoded as a bitmask in the multicast packet header within different encapsulations. A router that receives such a packet will forward the packet based on the bit position in the packet header towards the receiver (s) .

In a brown-field deployment of BIER, the network may contains a mix of “BIER capable” , “non-BIER capable” and “partial BIER capable” routers. Currently, there are three different methods known to support “non-BIER capable” routers.

For the sake of clarity, several terms involved in the present disclosure will be explained in the first place.

As used herein, the term “node” in the present disclosure may refer to a communication node included in a network, in the field of building multicast path and forwarding multicast traffic, the “node” may be an ingress router, an immediate router or an egress router, which is not limited in any one of the embodiments of the present disclosure unless otherwise specified.

The term “link” in the present disclosure may refer to an interface in the line card, in the field of building multicast path and forwarding multicast traffic, one router have many line cards, each line card have many interfaces, and an interface in the line card can be regarded as link. Normally, in IGP protocol, those skilled in the art always use the word “link” while advertising the properties of a particular interface, which is not limited in any one of the embodiments of the present disclosure unless otherwise specified.

The term “BIER capable” in the present disclosure may refer to an object that support BIER technology, and can be used for forwarding BIER packets, which is not limited in any one of the embodiments of the present disclosure unless otherwise specified.

The term “non-BIER capable” in the present disclosure may refer to an object that cannot support BIER technology, and cannot be used for forwarding BIER packets, which is not limited in any one of the embodiments of the present disclosure unless otherwise specified.

The term “capability information” in the present disclosure may refer to information about the BIER capability of a link, in some embodiments, the capability information may include a field indicating whether a link supports BIER forwarding; while in some embodiments, the capability information may include one or more bits, and each bit supports a BSL corresponding to an interface of a node, and the interface of the node corresponds to a link between two nodes; while in some embodiments, the capability information may include both the aforementioned field and the aforementioned one or more bits. For example, higher capability router can support “big” bit string length like 256, but lower capability router may support “small” bit string length like 64. The contents of the BIER link capability information is not limited in any one of the embodiments of the present disclosure unless otherwise specified.

FIG. 2 is a schematic view of a first solution for supporting “non-BIER capable” nodes in prior art, as shown in FIG. 2, node A can identify node B is a “non-BIER capable” node by IGP advertisement, and tunnel over “non-BIER capable” node B by dynamic unicast tunnels like Multi-Protocol Label Switch (MPLS) or Segment Routing (SR) tunnels when forwarding multicast traffic received from upstream node of node A. Then the multicast traffic from node A to node E follows: [A] - (tunnel) - [D] - [E] .

FIG. 3 is a schematic view of a second solution for supporting “non-BIER capable” nodes in prior art, as shown in FIG. 3, node A uses specific BIER Algorithm (BAR) or IGP Algorithm (IPA) to eliminate the “non-BIER capable” node B from the SPT computed using SPF when building the SPT. One example is draft-zzhang-bier-algorithm-00 Section 4.1 (BAR=1) which can eliminate “non-BIER capable” nodes from the SPT. Then the multicast traffic from node A to node E follows: [A] - [C] - [F] - [D] - [E] .

FIG. 4 is a schematic view of a third solution for supporting “non-BIER capable” nodes in prior art, as shown in FIG. 4, node A uses IGP multi-Topology feature to define multiple topologies for unicast and multicast, and excludes “non-BIER capable” node B from the “multicast” topology. Then the multicast traffic from node A to node E follows: [A] - [C] - [F] - [D] - [E] .

However, the first and second solution cited above have the technical problems that the packets forwarding would stop when encountering a “partial BIER capable” nodes in the network topology, and the third solution cited above can support “partial BIER capable” nodes, but have the technical problems that deploying multi-topology requires to touch the OAM or configuration of all the links in the network, and lose the simplicity of single topological view for both unicast and multicast network. Besides, not all operators do support IGP multi-topology. The technical problems of the first and second solution cited above are discussed following in conjunction with FIG. 5 and FIG. 6.

FIG. 5 is a schematic view of technical problems of the first solution in prior art, as shown in FIG. 5, node B is a “partial BIER capable” node, and the link connected node A with node B does not support BIER, but the SPT is not modified for BIER, because node A thinks node B is a “BIER capable” node, but node A cannot detect that the link connected node A with node B does not support BIER. So the SPT is not modified and resulting in “BIER forwarding failure” from node A to node E, the multicast traffic from node A to node E is dropped at node B when forwarding multicast traffic received from upstream node of node A.

FIG. 6 is a schematic view of technical problems of the second solution in prior art, as shown in FIG. 6, node B is a “partial BIER capable” node, and the link connected node A with node B does not support BIER, but the built SPT still using BAR=1 (constraint is must support BIER) , then the node A cannot detect that the link to the node B does not support BIER. So the SPT is not modified resulting in “BIER forwarding failure” from A to E, the multicast traffic from node A to node E is dropped at node B when forwarding multicast traffic received from upstream node of node A.

FIG. 7 is a schematic view of how partial BIER capable nodes can be supported by using multi-topology in prior art, as shown in FIG. 7, it is shown how “partial BIER capable” nodes can be supported by using multi-topology according to the third solution in prior art cited above, where node B is a “partial BIER capable” node, and the link connected node A with node B does not support BIER, using Mt=2 to build SPT for multicast traffic, nodes and links with Mt=2 can be added in the built SPT. Then the multicast traffic from node A to node E follows: [A] - [C] - [B] - [D] - [E] .

As can be seen from above, the technical solution in prior art have different problems.

Hence, aiming the above problem, objective of the invention is to support “partial BIER capable” nodes in the network without having to deploy “IGP multi-topology” . The present disclosure provides a method for advertising and processing BIER capability of link, where the “BIER capability” of each link is advertised in the IGP protocol packet, for example, OSPF and ISIS, then the simple technique as mentioned in the first solution and the second solution cited above can be used to eliminate the non-BIER capable links from the SPT calculated for BIER forwarding. This would enable the administrator to deploy BIER technology in a brown-field deployment with “partial BIER capable” nodes without having to configure and enable the complicated IGP multi-topology.

Embodiments of the present disclosure will be elaborated in detail as follows.

FIG. 8 is a schematic flowchart of a first method for advertising and processing BIER capability of link according to an embodiment of the present disclosure. This method shows an interaction operation between a first node and a second node, where both the first node and the second node may be BIER nodes in a network and the first node may be an upstream node of the second node.

The method includes the following steps:

S801: the second node determines first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the second node, where the interface of the second node corresponds to a first link between the second node and a first node.

First of all, a node can know one or more BSL corresponding to an interface thereof, and the interface of the node corresponds to a link between the node and an upstream node thereof. The one or more BSL corresponding to an interface can be indicated as the first capability information. It should be noted that there may be several links between the second node and the first node; the second node may know the BSL corresponding to all interfaces connected to certain links thereof.

It should be noted that the term “first link” is refer to link (s) between the first node and the second node, even though there is no “second link” , the term “first link” is still used to make the description of the disclosure more concise and clear.

In one possible implementation, the first capability information can be included in a sub-TLV of the first packet. FIG. 9 is a schematic view of a sub-TLV according to an embodiment of the present disclosure, as shown in FIG. 9, the field “Type value” will be assigned by the Internet Assigned Numbers Authority (IANA) from appropriate registries, the field “Length” is set to 4, the field “BSL Flag (BSL capability) ” is a 8-bit long bit-map field with each bit if set, specifying the capability to support particular “BIER bit string length” as follows:

*bit-1 -BSL 64 is supported

*bit-2 -BSL 128 is supported

*bit-3 -BSL 256 is supported

*bit-4 -BSL 512 is supported

*bit-5 -BSL 1024 is supported

*bit-6 -BSL 2048 is supported

*bit-7 -BSL 4096 is supported

*bit-8 -reserved

In one possible implementation, the field “BSL Flag (BSL capability) ” represents the first capability information.

S802: the second node advertises a first packet to the first node, where the first packet includes the first capability information.

Then if the second node specified in this embodiment determines the first capability information, the second node advertises a first packet to the first node.

S803: the first node receives the first packet from the second node.

S804: the first node determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link between the second node and the first node.

For example, when the first node and the second node are router A and router B, it is assumed that router A and router B connected by single link (link-1) . For one scenario, router B advertises a first packet to the router A, first capability information is included in the first packet, and the first capability information includes one bit supports a BSL 256 corresponding to an interface of router B. If the BSL corresponding to an interface of router A is 64, router A determines that the bit included in the first capability information does not support the BSL corresponding to the interface of the router A, and if the BSL corresponding to an interface of router A is 256, router A determines that the bit included in the first capability information supports the BSL corresponding to the interface of the router A, where both the interface of router A and the interface of router B corresponds to the link-1. For another scenario, router B advertises a first packet to the router A, first capability information is included in the first packet, and the first capability information includes two bits support BSL 256 and 64 corresponding to an interface of router B. If the BSL corresponding to an interface of router A is 128, router A determines that the bits included in the first capability information do not support the BSL corresponding to the interface of the router A, and if the BSL corresponding to an interface of router A is 256 or 64, router A determines that the bits included in the first capability information support the BSL corresponding to the interface of the router A, where both the interface of router A and the interface of router B corresponds to the link-1. It should be noted that there may be one or more bits included in the first capability information, which not limited to one or two as discussed herein.

S805: the first node establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node.

FIG. 10 is a schematic view of an example application scenario according to an embodiment of the present disclosure, as shown in FIG. 10, the application scenario and topology is same as the application scenario and topology in FIG. 5, SPT is modified for BIER to tunnel over (bypass) non-BIER capable nodes and links, and can use unicast tunnel to tunnel over (bypass) the non-BIER capable node B, then the multicast traffic from node A to node E follows: [A] - (tunnel) - [D] - [E] .

It should be understand that there is another situation that if the one or more bits included in the first capability information support the BSL corresponding to the interface of the first node, the first node forwards traffic to the second node for BIER forwarding.

For example, during traffic forwarding, if the first node determines that the one or more bits included in the first capability information support the BSL corresponding to the interface of the first node, which indicates that the second node can be used for forwarding the t traffic, then the first node forwarding the traffic to the second node. The traffic is data need to be forwarded through the network, for example, the multicast traffic in BIER network.

In another application scenario regarding building a BIER SPT, if the first node determines the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, then the first node adds the second node in BIER SPF.

It should be understand that there is another situation that if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, the first node eliminates the second node when building BIER SPT by using SPF.

The present disclosure provides a method for advertising and processing BIER capability of link, where the second node determines first capability information including one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, where the interface of the second node corresponds to a first link between the second node and a first node, then the second node advertises a first packet to the first node, where the first packet includes the first capability information. The first node receives the first packet from the second node, determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link, then establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, the technical solution of this embodiment can support the partial BIER capable nodes in the network without deploying the complicated IGP multi-topology technology. In a scenario encountering a partial BIER capable node in the network topology during traffic forwarding, the first node determines whether to forward the traffic to the partial BIER capable node or not based on the first capability information. The traffic can be forwarded even encountering a partial BIER capable node in the network topology.

FIG. 11 is a schematic flowchart of a second method for advertising and processing BIER capability of link according to an embodiment of the present disclosure. This method shows an interaction operation between a first node and a second node, where both the first node and the second node may be BIER nodes in a network, and the first node may be an upstream node of the second node. The difference between this embodiment and the embodiment specified by FIG. 8 is that the first packet further includes second capability information.

The method includes the following steps:

S1101: the second node determines first capability information including one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, where the interface of the second node corresponds to a first link between the second node and a first node.

Reference may be made to the description in S801.

S1102: the second node advertises a first packet to the first node, where the first packet includes the first capability information.

Reference may be made to the description in S802.

S1103: the first node receives the first packet from the second node.

Reference may be made to the description in S803.

S1104: the first node determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link.

Reference may be made to the description in S804.

S1105: the first node determines whether the second capability information indicates the first link supports BIER forwarding if the one or more bits included in the first capability information support the BSL corresponding to the interface of the first node.

In one possible implementation, the second capability information may be a filed in the first packet, and different values of this filed indicate whether the first link supports BIER forwarding or not. In one possible implementation, the second capability information may be included in a sub-TLV, and the presence of this sub-TLV indicates the first link supports BIER forwarding, and if the first node receives a packet without this sub-TLV, the first node determines the first link does not support BIER forwarding.

In one possible implementation, where the first capability information and the second capability information are included in a sub-TLV of the first packet; if the first packet is an IGP OSPF LSA packet, the sub-TLV is included in OSPF Extended Link Opaque LSA under the OSPF Extended Link TLV; if the first packet is an IGP ISIS LSP packet, the sub-TLV is included under TLV-22 of the first packet or TLV-23 of the first packet.

In these two possible implementations cited above, the first capability information and the second capability information can be carried under different TLV in different protocol, and the packet can be LSA or LSP packet, then the technical solution have better compatibility with the existing protocols.

S1106: the first node adds the second node to a BIER SPT by using SPF if the second capability information indicates the first link supports BIER forwarding.

It is an application scenario regarding building a BIER SPT, if the first node determines the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, and further determines the second capability information indicates the first link supports BIER forwarding, then the first node adds the second node in BIER SPF.

It should be understand that there is another situation that if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, or the second capability information indicates the first link does not support BIER forwarding, the first node eliminates the second node when building BIER SPT by using SPF.

FIG. 12 is a schematic view of another example application scenario according to an embodiment of the present disclosure, as shown in FIG. 12, the application scenario and topology is same as the application scenario and topology in FIG. 6, the SPT for BIER is built based on the constraint is link and node Must support BIER, so the “non-BIER capable” link A-B is eliminated when building the SPT, but yet, the SPF includes node B in the SPT since it can support BIER forwarding via link C-B, then the multicast traffic from node A to node E follows: [A] - [C] - [B] - [D] - [E] .

In another application scenario regarding traffic forwarding, if the first node determines the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, and further determines the second capability information indicates the first link supports BIER forwarding, then the first node forwards the traffic to the second node for BIER forwarding.

It should be understand that there is another situation that if the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, or the second capability information indicates the first link does not support BIER forwarding, the first node establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding.

The present disclosure provides a method for advertising and processing BIER capability of link, where the second node determines first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the second node, where the interface of the second node corresponds to a first link between the second node and a first node, then the second node advertises a first packet to the first node, where the first packet includes the first capability information. The first node receives the first packet from the second node, determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link, then determines whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node, where the interface of the first node corresponds to the first link, finally adds the second node to a BIER SPT by using SPF if the second capability information indicates the first link supports BIER forwarding, the technical solution of this embodiment can support the partial BIER capable node and forward traffic or build SPT according to the condition of the partial BIER capable node in the network without deploying the complicated IGP multi-topology technology, where both the first capability information and the second capability information are considered during SPT building or traffic forwarding.

FIG. 13 is a structural view of a first apparatus for processing BIER capability of link according to an embodiment of the present disclosure, as shown in FIG. 13, where the apparatus includes: a receiving module 1301, a first determining module 1302 and an establishing module 1303.

The receiving module 1301 is configured to receive a first packet from a second node, where the first packet includes first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the apparatus.

The first determining module 1302 is configured to determine whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the apparatus, where the interface of the apparatus corresponds to the first link.

The establishing module 1303 is configured to establish a tunnel between the apparatus and a third node to bypass the second node for BIER forwarding if the first determining module determines that the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the apparatus.

In an embodiment, where the first packet further includes second capability information, the first determining module 1302 is specifically configured to determine whether the second capability information indicates the first link supports BIER forwarding if the first determining module determines that the one or more bits included in the first capability information support the BSL corresponding to the interface of the apparatus, and the establishing module 1303 is specifically configured to establish the tunnel between the apparatus and the third node if the second capability information indicates the first link does not support BIER forwarding.

FIG. 14 is a structural view of a second apparatus for processing BIER capability of link according to an embodiment of the present disclosure, as shown in FIG. 14, besides the a receiving module 1301, a first determining module 1302 and the establishing module 1303, the apparatus further includes an adding module 1304, the adding module 1304 is configured to add the second node to a BIER SPT by using SPF if the second capability information indicates the first link supports BIER forwarding.

FIG. 15 is a structural view of an apparatus for advertising BIER capability of link according to an embodiment of the present disclosure, as shown in FIG. 15, where the apparatus includes: a second determining module 1501 and an advertising module 1502.

The second determining module 1501 is configured to determine first capability information including one or more bits, and each bit supports a BSL corresponding to an interface of the apparatus, and the interface of the apparatus corresponds to a first link between the apparatus and a first node.

The advertising module 1502 is configured to advertise a first packet to a first node, where the first packet includes the first capability information.

In an embodiment, where the first packet further includes second capability information, where the second capability information is used for indicating the first link supports BIER forwarding; the second determining module 1501 is further configured to determine the second capability information; the advertising module 1502 is configured to advertise the second capability information.

The present disclosure also provides a first apparatus processing BIER capability of link which includes a processor and a memory. The memory is storing instructions that cause the processor to perform the method according to the method described above.

The present disclosure also provides a second apparatus advertising BIER capability of link which includes a processor and a memory. The memory is storing instructions that cause the processor to perform the method according to the method described above.

The present disclosure also provides a first computer-readable storage medium having stored thereon instructions that when executed cause one or more processors configured to process BIER capability of link is proposed. The instructions cause the one or more processors to perform the method described above.

The present disclosure also provides a second computer-readable storage medium having stored thereon instructions that when executed cause one or more processors configured to advertise BIER capability of link is proposed. The instructions cause the one or more processors to perform the method described above.

The present disclosure also provides a first communication node including an apparatus for processing BIER capability of link according to the above embodiments.

The present disclosure also provides a second communication node including an apparatus for advertising BIER capability of link according to the above embodiments.

Terms such as “first” , “second” and the like in the specification and claims of the present disclosure as well as in the above drawings are intended to distinguish different objects, but not intended to define a particular order.

The term such as “and/or” in the embodiments of the present disclosure is merely used to describe an association between associated objects, which indicates that there may be three relationships, for example, A and/or B may indicate presence of A only, of both A and B, and of B only.

The term “a” or “an” is not intended to specify one or a single element, instead, it may be used to represent a plurality of elements where appropriate.

In the embodiments of the present disclosure, expressions such as “exemplary” or “for example” are used to indicate illustration of an example or an instance. In the embodiments of the present disclosure, any embodiment or design scheme described as “exemplary” or “for example” should not be interpreted as preferred or advantageous over other embodiments or design schemes. In particular, the use of “exemplary” or “for example” is aimed at presenting related concepts in a specific manner.

In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit.

FIG. 16 is a schematic diagram of a hardware device 1600 that may for example, comprise nodes or functional entities of the communications system, and the hardware device 1600 is configured to perform any or all of steps of the above methods and features described herein, according to different embodiments of the present invention. In some embodiments, the hardware device may be an element of communications network infrastructure, such as a router or a switch. Furthermore, a device may contain multiple instances of a component, such as multiple processors, memories, transmitters, receivers, transceivers etc. As shown in FIG. 16, the hardware device 1600 includes a processor 1605 such as a Central Processing Unit (CPU) , and may further include specialized processors such as a Graphics Processing Unit (GPU) or other such processor, memory 1620, non-transitory mass storage 1610, I/O interface 1625, network interface 1615, and a transceiver 1630, all of which are communicatively coupled via bi-directional bus. According to certain embodiments, any or all of the depicted elements may be utilized, or only a subset of the elements. Further, device may contain multiple instances of certain elements, such as multiple processors, memories, or transceivers. Also, elements of the hardware device may be directly coupled to other elements without the bi-directional bus..

The memory 1620 may include any type of non-transitory memory such as static random access memory (SRAM) , dynamic random access memory (DRAM) , synchronous DRAM (SDRAM) , read-only memory (ROM) , any combination of such, or the like. The mass storage element may include any type of non-transitory storage device, such as a solid state drive, hard disk drive, a magnetic disk drive, an optical disk drive, USB drive, or any computer program product configured to store data and machine executable program code. In some embodiments, mass storage may be integrated with a heterogeneous memory. According to certain embodiments, the memory or mass storage may have recorded thereon statements and instructions executable by the processor for performing any of the aforementioned method steps described above.

The hardware device 1600 can include one or more network interfaces 1615, which may include at least one of a wired network interface and a wireless network interface. A network interface may include a wired network interface to connect to a network, and also may include a radio access network interface for connecting to other devices over a radio link. When hardware device is a network infrastructure element, the radio access network interface may be omitted for nodes or functions acting as elements of the PLMN other than those at the radio edge (e.g. an eNB) . When hardware device 1600 is infrastructure at the radio edge of a network, both wired and wireless network interfaces may be included. When hardware device 1600 is a wirelessly connected device, such as a User Equipment, radio access network interface may be present and it may be supplemented by other wireless interfaces such as WiFi network interfaces. The network interfaces allow the hardware device 1600 to communicate with remote entities such as those connected to network.

According to embodiments, a video adapter and the I/O interface 1625 provide interfaces to couple the hardware device 1600 to external input and output devices. Examples of input and output devices include a display coupled to the video adapter and an I/O device such as a touch-screen coupled to the I/O interface. Other devices may be coupled to the hardware device 1600, and additional or fewer interfaces may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device. In some embodiments, hardware device 1600 may be a standalone device, while in other embodiments hardware device 1600 may be resident within a router or switch.

Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storage media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory, tangible storage media. Disk and disc, as used herein, includes compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs) , general purpose microprocessors, application specific integrated circuits (ASICs) , field programmable logic arrays (FPGAs) , or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor, ” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combined codec. Also, the techniques could be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC) or a set of ICs (e.g., a chip set) . Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a codec hardware unit or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

Claims

A method for processing Bit Index Explicit Replication, BIER, capability of link, comprising:

receiving, by a first node, a first packet from a second node, wherein the first packet comprises first capability information comprising one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the first node;

determining, by the first node, whether the one or more bits comprised in the first capability information support a BSL corresponding to an interface of the first node, wherein the interface of the first node corresponds to the first link;

if the one or more bits comprised in the first capability information do not support the BSL corresponding to the interface of the first node, establishing, by the first node, a tunnel between the first node and a third node to bypass the second node for BIER forwarding.
The method according to claim 1, wherein the first packet further comprises second capability information, and the method further comprises:

if the one or more bits comprised in the first capability information support the BSL corresponding to the interface of the first node, determining, by the first node, whether the second capability information indicates the first link supports BIER forwarding;

if the second capability information indicates the first link does not support BIER forwarding, establishing, by the first node, the tunnel between the first node and the third node.
The method according to claim 2, wherein the method further comprises:

if the second capability information indicates the first link supports BIER forwarding, adding, by the first node, the second node to a BIER shortest path tree, SPT, by using shortest path first, SPF.
The method according to claim 2 or 3, wherein the first capability information and the second capability information are comprised in a sub-TLV of the first packet;

if the first packet is an Interior Gateway Protocol, IGP, Open Shortest Path First routing protocol, OSPF, Link State Advertisement, LSA, packet, the sub-TLV is comprised in OSPF Extended Link Opaque LSA under the OSPF Extended Link TLV.
The method according to claim 2 or 3, wherein the first capability information and the second capability information are comprised in a sub-TLV of the first packet;

if the first packet is an IGP Intermediate System-Intermediate System routing protocol, ISIS, Link State Protocol, LSP, packet, the sub-TLV is comprised under TLV-22 of the first packet or TLV-23 of the first packet.
A method for advertising Bit Index Explicit Replication, BIER, capability of link, comprising:

determining, by a second node, first capability information comprising one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and a first node;

advertising, by the second node, a first packet to a first node, wherein the first packet comprises the first capability information.
The method according to claim 6, wherein the first packet further comprises second capability information, wherein the second capability information is used for indicating the first link supports BIER forwarding;

the method further comprises:

determining, by the second node, the second capability information;

advertising, by the second node, the second capability information.
The method according to claim 7, wherein the first capability information and the second capability information are comprised in a sub-TLV of the first packet;

if the first packet is an Interior Gateway Protocol, IGP, Open Shortest Path First routing protocol, OSPF, Link State Advertisement, LSA, packet, the sub-TLV is comprised in OSPF Extended Link Opaque LSA under the OSPF Extended Link TLV.
The method according to claim 7, wherein the first capability information and the second capability information are comprised in a sub-TLV of the first packet;

if the first packet is an IGP Intermediate System-Intermediate System routing protocol, ISIS, Link State Protocol, LSP, packet, the sub-TLV is comprised under TLV-22 of the first packet or TLV-23 of the first packet.
An apparatus for processing Bit Index Explicit Replication, BIER, capability of link, comprising:

a receiving module, configured to receive a first packet from a second node, wherein the first packet comprises first capability information comprising one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the second node, and the interface of the second node corresponds to a first link between the second node and the apparatus;

a first determining module, configured to determine whether the one or more bits comprised in the first capability information support a BSL corresponding to an interface of the apparatus, wherein the interface of the apparatus corresponds to the first link;

an establishing module, configured to establish a tunnel between the apparatus and a third node to bypass the second node for BIER forwarding if the first determining module determines that the one or more bits comprised in the first capability information do not support the BSL corresponding to the interface of the apparatus.
The apparatus according to claim 10, wherein the first packet further comprises second capability information, the first determining module is specifically configured to:

determine whether the second capability information indicates the first link supports BIER forwarding, if the first determining module determines that the one or more bits comprised in the first capability information support the BSL corresponding to the interface of the apparatus;

the establishing module is specifically configured to:

establish the tunnel between the apparatus and the third node if the second capability information indicates the first link does not support BIER forwarding.
The apparatus according to claim 11, wherein the apparatus further comprises an adding module, configured to:

add the second node to a BIER shortest path tree, SPT, by using shortest path first, SPF if the second capability information indicates the first link supports BIER forwarding.
An apparatus for advertising Bit Index Explicit Replication, BIER, capability of link, comprising:

a second determining module, configured to determine first capability information comprising one or more bits, and each bit supports a Bit String Length, BSL, corresponding to an interface of the apparatus, and the interface of the apparatus corresponds to a first link between the apparatus and a first node;

an advertising module, configured to advertise a first packet to a first node, wherein the first packet comprises the first capability information.
The apparatus according to claim 13, wherein the first packet further comprises second capability information, wherein the second capability information is used for indicating the first link supports BIER forwarding;

the second determining module is further configured to determine the second capability information;

the advertising module is further configured to advertise the second capability information.