CN113016165B

CN113016165B - Method and apparatus for advertising and processing BIER capabilities of a link and communication node

Info

Publication number: CN113016165B
Application number: CN201880099263.9A
Authority: CN
Inventors: 森蒂尔·达纳拉吉; 谢经荣
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-10-31
Filing date: 2018-10-31
Publication date: 2022-09-16
Anticipated expiration: 2038-10-31
Also published as: CN113016165A; WO2020087398A1

Abstract

The present invention provides a method and apparatus for advertising and processing the BIER capability of a link, and a communication node, wherein a first node: receiving a first packet from a second node, wherein the first packet includes first capability information including one or more bits, each Bit supporting 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 whether the one or more bits included in the first capability information support a BSL corresponding to an interface of the first node corresponding to the first link; and when the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, establishing a tunnel between the first node and a third node to bypass the second node for BIER forwarding. The technical scheme in the embodiment can support nodes with partial BIER capability in the network, and does not need to deploy complex IGP multi-topology technology.

Description

Method and apparatus for advertising and processing BIER capabilities of a link and communication node

Technical Field

The present invention 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 the BIER technology, if a Router advertises BIER information through an underlying Interior Gateway Protocol (IGP), the IGP Router is considered as a "BIER-capable Router" or a "BIER Forwarding Router (BFR)". If a router does not advertise BIER information via the underlying IGP, the IGP router is considered a "BIER-incapable router" or a "non-BFR".

However, some BIER routers may have multiple line cards, some line cards support BIER, and some line cards do not support BIER (as shown in fig. 1), where a router has multiple line cards, each line card has multiple interfaces, and the interfaces on the line cards may be viewed as links. Such routers are referred to as "partial BIER capable routers" or "partial BFRs". In brown deployment of BIER (where clients have adopted existing Multicast technologies such as Protocol Independent Multicast (PIM), Multicast Label Distribution Protocol (MLDP), and Resource Reservation Protocol for Traffic Engineering extensions (RSVP-TE) and are intended to be replaced by more advantageous BIER technologies), the network may include "BIER capable", "no BIER capable", and "partial BIER capable" routers. The use of BIER header fields to forward multicast packets requires special hardware, so it is important to support migration from existing multicast technologies (PIM, MLDP and RSVP-TE) to BIER in brown deployments.

Several methods have been proposed to support routers without BIER capability, but some do not support routers with partial BIER capability, and some can support routers with partial BIER capability by deploying multi-topology technology. However, the deployment of multi-topology technology to support routers without BIER capability depends on the subjective intentions of the network operator. Moreover, deployment of multi-topology techniques requires access to Operations, administration and maintenance (OAM) or configuration of all links in the network, and both unicast and multicast networks may lose the simplicity of a single topology view.

This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. It is neither allowed nor should it be construed that any of the above information constitutes prior art against the present invention.

Disclosure of Invention

In view of the above, to solve the above problems, the present invention provides a method and apparatus for advertising and handling BIER capability of a link, and a communication node.

The above and other objects are achieved by the subject matter of the independent claims. Further embodiments are evident from the dependent claims, the detailed description and the drawings.

According to a first aspect, the invention relates to a method for handling BIER capabilities of a link, wherein a first node: receiving a first packet from a second node, where the first packet includes first capability information including one or more bits, each Bit supporting 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 whether the one or more bits included 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; when the one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node, a tunnel is established between the first node and a third node to bypass the second node for BIER forwarding.

The method for processing the BIER capability of the link can support nodes with partial BIER capability in a network, and does not need to deploy complex IGP multi-topology technology. In a scenario in which a partial BIER-capable node in a network topology is encountered during traffic forwarding, the first node determines whether to forward the traffic to the partial BIER-capable node based on the first capability information. The traffic may be forwarded even if a partially BIER-capable node in the network topology is encountered.

Likewise, in a first possible implementation manner of the method according to the first aspect, the first packet further includes second capability information, when 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 further determines whether the second capability information indicates that the first link supports BIER forwarding, and when the second capability information indicates that the first link does not support BIER forwarding, the tunnel is established between the first node and the third node.

The second capability information is further included in the first message, and the first node further determines whether the second capability information indicates that 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 in which a partially BIER-capable node in a network topology is encountered during traffic forwarding, the first node determines whether to forward the traffic to the partially BIER-capable node based on the first capability information and the second capability information simultaneously. The traffic may be forwarded even if a partially BIER-capable node in the network topology is encountered.

In a second possible implementation of the method according to the first possible implementation of the method, when the second capability information indicates that the first link supports BIER forwarding, the first node further adds the second node to a BIER Shortest Path Tree (SPT) by using a Shortest Path First (SPF) algorithm.

In a scenario in which a partially BIER-capable node in a network topology is encountered during SPT setup, the first node determines to add the second node to a BIER SPT by using an SPF algorithm when the second capability information indicates that the first link supports BIER forwarding. The traffic may be forwarded even if a partially BIER-capable node in the network topology is encountered.

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

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

The third possible implementation manner and the fourth possible implementation manner indicate that the first capability information and the second capability information may be carried in different TLVs of different protocols, and the packet may be an LSA or an LSP packet, so that the technical solution may be better compatible with the existing protocol.

According to a second aspect, the invention relates to a method for advertising BIER capabilities of a link, wherein a second node: determining first capability information comprising one or more bits, each bit supporting a BSL corresponding to an interface of the second node corresponding to a first link between the second node and a first node; and then advertising a first message to the first node, wherein the first message comprises the first capability information.

The method for advertising the BIER capability of the link can support nodes with partial BIER capability in a network, and does not need to deploy complex IGP multi-topology technology.

Likewise, in a first possible implementation manner of the method according to the second aspect, the first packet further includes second capability information, where the second capability information is used to indicate that the first link supports BIER forwarding, and the second node further determines the second capability information and advertises the second capability information.

The second capability information also indicates that, in the first data, the first data may also be used by the first node to determine whether the second capability information indicates that the first link supports BIER forwarding.

In a second possible implementation of the method according to the first possible implementation of the method, wherein the first capability information and the second capability information are contained in a sub-TLV of the first packet; and if the first message is an IGP OSPF LSA message, the sub-TLV is contained in an OSPF extended link opaque LSA under the OSPF extended link TLV.

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

The second possible implementation manner and the third possible implementation manner indicate that the first capability information and the second capability information may be carried in different TLVs of different protocols, and the packet may be an LSA or LSP packet, so that the technical solution may be better compatible with the existing protocol.

According to a third aspect, the present invention relates to an apparatus for advertising BIER capability of a link, the apparatus including a receiving module, a first determining module, and an establishing module, the receiving module being configured to receive a first packet from a second node, where the first packet includes first capability information including one or more bits, each bit supporting 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 device and a third node to bypass the second node for BIER forwarding when 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 device.

Likewise, in a first possible implementation manner of the apparatus according to the third aspect, where the first packet further includes second capability information, when 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 first determining module is dedicated to determining whether the second capability information indicates that the first link supports BIER forwarding; the establishing module is dedicated to establishing the tunnel between the apparatus and the third node when the second capability information indicates that the first link does not support BIER forwarding.

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

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

Likewise, in a first possible implementation manner of the apparatus according to the fourth aspect, the first packet further includes second capability information, where the second capability information is used to indicate that the first link supports BIER forwarding; the second determining module is further configured to determine the second capability information; the advertisement module is further configured to advertise the second capability information.

The method according to the first aspect of the invention may be performed by the apparatus according to the third aspect of the invention. The method according to the second aspect of the invention may be performed by the apparatus according to the fourth aspect of the invention. Further features and embodiments of the method according to the first aspect of the invention derive directly from the function of the device according to the third aspect of the invention and its different embodiments. Further features and embodiments of the method according to the second aspect of the invention stem directly from the function of the device according to the fourth aspect of the invention and its different embodiments.

According to a fifth aspect, the invention relates to an apparatus for handling BIER capabilities of a link, comprising a processor and a memory. The memory stores instructions that cause the processor to perform the method according to the first aspect.

According to a sixth aspect, the present invention is directed to an apparatus for advertising BIER capabilities of a link, comprising a processor and a memory. The memory stores instructions that cause the processor to perform the method according to the second aspect.

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

According to an eighth aspect, there is provided a computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to advertise BIER capability of a link. 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 invention relates to a first communication node comprising means for handling the BIER-capability of a link according to the third or the fifth aspect.

According to a tenth aspect, the invention relates to a second communication node comprising means for advertising BIER capabilities of a link according to the fourth or the sixth aspect.

The implementation and technical effects of the above-described device can be referred to the implementation and technical effects of the above-described method.

By the method or the device for advertising and processing the BIER capability of the link, the nodes with partial BIER capability in the network can be supported, and complex IGP multi-topology technology does not need to be deployed.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, and are incorporated in and constitute a part of this specification. In the drawings:

FIG. 1 is a schematic diagram of a router with partial BIER capability;

FIG. 2 is a schematic diagram of a first prior art scheme for supporting "BIER-less capable" nodes;

FIG. 3 is a schematic diagram of a second prior art scheme for supporting "BIER-less capable" nodes;

FIG. 4 is a schematic diagram of a third prior art scheme for supporting "BIER-less capable" nodes;

figure 5 is a schematic illustration of the technical problem of the first solution in the prior art;

fig. 6 is a schematic diagram of a technical problem of the second scheme in the prior art;

FIG. 7 is a schematic diagram of how partial BIER capable nodes are supported using multi-topology techniques in the prior art;

FIG. 8 is a schematic flow chart diagram of a first method for advertising and processing BIER capabilities of a link in accordance with an embodiment of the present invention;

fig. 9 is a schematic diagram of a sub-TLV according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of an example application scenario in accordance with an embodiment of the present invention;

FIG. 11 is a schematic flow chart diagram of a second method for advertising and handling BIER capabilities of a link in accordance with an embodiment of the present invention;

FIG. 12 is a schematic diagram of another exemplary application scenario in accordance with an embodiment of the present invention;

fig. 13 is a structural view of a first apparatus for handling BIER capability of a link according to an embodiment of the present invention;

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

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

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

Detailed Description

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

It will be appreciated that the same applies to apparatus or systems corresponding to the method for performing the method, and vice versa, in connection with the method described. For example, if one or more particular method steps are described, the corresponding apparatus may include one or more elements, e.g., functional elements, for performing the described one or more method steps (e.g., one element that performs the one or more steps, or multiple elements, each element performing one or more of the multiple steps), even if such one or more elements are not explicitly described or illustrated in the figures. Also, for example, if a particular apparatus is described based on one or more units (e.g., functional units), the corresponding method may include one step of performing the function of the one or more units (e.g., one step of performing the function of the one or more units, or multiple steps, each step performing the function of one or more of the number of units), even if such one or more steps are not explicitly described or illustrated in the figures. Further, it is to be understood that 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 a structure that provides optimal multicast forwarding through the "BIER domain" without the need for intermediate routers to maintain any multicast-related per-stream state. In the BIER architecture, each receiver is represented by a unique bit in a bit mask, and all intended multicast receivers are encoded as bit masks in multicast headers within different encapsulations. A router receiving such a message will forward the message to a receiver based on the bit position in the header of the message.

In a brown deployment of BIER, the network may include "BIER-capable", "no BIER-capable", and "partial BIER-capable" routers. Currently, three different approaches are known to support routers that are "without BIER capability".

For clarity, several terms involved in the present invention will be explained first.

As used herein, the term "node" in the present invention may refer to a communication node included in a network, and in the field of establishing a multicast path and forwarding multicast traffic, the "node" may be an ingress router, an intermediate router, or an egress router, and is not limited to any embodiment of the present invention unless otherwise specified.

The term "link" in the present invention may refer to an interface on a line card, and in the field of establishing a multicast path and forwarding multicast traffic, one router has a plurality of line cards, each line card has a plurality of interfaces, and each interface on a line card can be regarded as a link. Generally, in IGP protocols, those skilled in the art will always use the term "link" when advertising the properties of a particular interface, and unless otherwise stated, is not limited to any embodiment of the invention.

The term "BIER-capable" in the present invention may refer to an object that supports BIER technology and may be used to forward BIER packets, and is not limited to any embodiment in the present invention unless otherwise specified.

The term "no IER capability" in the present invention may refer to an object that does not support BIER technology and may not be used to forward BIER messages, and is not limited to any of the embodiments in the present invention unless otherwise specified.

The term "capability information" in this disclosure may refer to information about the BIER capability of a link, which may include a field indicating whether the link supports BIER forwarding in some embodiments; in some embodiments, the capability information may include one or more bits, each bit supporting a BSL corresponding to an interface of a node corresponding to a link between two nodes; and in some embodiments, the capability information may include both the field and the one or more bits. For example, a high-capability router may support a "large" bit string length, e.g., 256, but a low-capability router may support a "small" bit string length, e.g., 64. Unless otherwise stated, the content of BIER link capability information is not limited to any embodiment of the invention.

Fig. 2 is a schematic diagram of a first scheme for supporting a node without BIER capability in the prior art, and as shown in fig. 2, a node a may recognize that a node B is a node without BIER capability through IGP advertisement, and when forwarding multicast traffic received from an upstream node of the node a, a dynamic unicast tunnel, such as a Multi-Protocol Label Switch (MPLS) tunnel or a Segment Routing (SR) tunnel, spans the node B without BIER capability.

Fig. 3 is a diagram of a second scheme of the prior art for supporting "no BIER capability" nodes, as shown in fig. 3, a node a removes "no BIER capability" node B from the SPT calculated using the SPF Algorithm when the SPT is established using a specific BIER Algorithm (BAR) or IGP Algorithm (IPA). An example is draft-zzhang-BIER-algorithmm-00 section 4.1 (BAR ═ 1), which can remove "BIER-incapable" nodes from the SPT. The multicast traffic path from node a to node E is therefore: [A] - [ C ] - [ F ] - [ D ] - [ E ].

Fig. 4 is a schematic diagram of a third scheme for supporting "no BIER capability" nodes in the prior art. As shown in fig. 4, node a employs IGP multi-topology characteristics to define multiple topologies of unicast and multicast, and excludes "BIER-incapable" node B from the "multicast" topology. The multicast traffic path from node a to node E is therefore: [A] - [ C ] - [ F ] - [ D ] - [ E ].

However, the above-described first and second solutions have the following technical problems: when a node with partial BIER capability in the network topology is encountered, the packet forwarding will stop, and although the third scheme can support the node with partial BIER capability, the following technical problems exist: deploying multi-topology technology requires access to OAM or configuration of all links in the network, and both unicast and multicast networks lose the simplicity of a single topology view. Furthermore, not all operators support IGP multi-topology technologies. The technical problems of the first and second schemes described above are discussed below in conjunction with fig. 5 and 6.

Fig. 5 is a schematic diagram illustrating a technical problem of the first solution in the prior art, as shown in fig. 5, a node B is a "partial BIER-capable" node, and a link connecting the node a to the node B does not support BIER, but SPT is not modified for BIER, because the node a considers that the node B is a "BIER-capable" node, but the node a cannot detect that the link connecting the node a to the node B does not support BIER. Thus, the SPT is not modified, resulting in a "BIER forwarding failure" from node a to node E, and when forwarding multicast traffic received from nodes upstream of node a, the multicast traffic from node a to node E is dropped at node B.

Fig. 6 is a schematic diagram illustrating a technical problem of a second scheme in the prior art, as shown in fig. 6, node B is a "partial BIER capable" node, and the link connecting node a to node B does not support BIER, but the established SPT still uses BAR 1 (the limitation is that BIER must be supported), so node a cannot detect that the link to node B does not support BIER. Thus, the SPT is not modified, resulting in a "BIER forwarding failure" from a to E, and when forwarding multicast traffic received from a node upstream of node a, the multicast traffic from node a to node E is dropped at node B.

Fig. 7 is a schematic diagram of how to support a node with partial BIER capability by using a multi-topology technology in the prior art, and as shown in fig. 7, it is illustrated how to support a node with partial BIER capability by using a multi-topology technology according to the third scheme in the prior art, where a node B is a node with partial BIER capability, a link connecting a to the node B does not support BIER, and an SPT is established for multicast traffic using Mt 2, and a node and a link with Mt 2 may be added to the established SPT. The multicast traffic path from node a to node E is therefore: [A] - [ C ] - [ B ] - [ D ] - [ E ].

From the above description it can be seen that the prior art solutions suffer from different problems.

Therefore, in view of the above problems, it is an object of the present invention to support "partially BIER-capable" nodes in a network without deploying "IGP multi-topology technology". The present invention provides a method for advertising and processing BIER capabilities of links, wherein the "BIER capabilities" of each link are advertised in IGP protocol messages, e.g., OSPF and ISIS, and then links without BIER capabilities can be removed from the computed SPTs for BIER forwarding using the simple techniques mentioned in the first and second schemes above. This would enable administrators to deploy BIER technology in brown deployments with "partially BIER capable" nodes without the need to configure and enable sophisticated IGP multi-topology technologies.

Embodiments of the present invention will be described in detail below.

Fig. 8 is a schematic flow chart diagram of a first method for advertising and handling BIER capabilities of a link in accordance with an embodiment of the invention. The method shows an interaction between a first node and a second node, where both the second 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 comprises the following steps:

s801: the second node determines first capability information comprising one or more bits, each bit supporting a BSL corresponding to an interface of the second node, wherein the interface of the second node corresponds to a first link between the second node and a first node.

First, a node may learn one or more BSLs corresponding to its interface, and the interface of the node corresponds to a link between the node and its upstream node. One or more BSLs corresponding to the interface may be indicated as the first capability information. It should be noted that there may be multiple links between the second node and the first node; the second node may learn the BSLs corresponding to the interfaces of some of the links to which it is connected.

It should be noted that the term "first link" refers to a link between a first node and a second node, and even if the "second link" does not exist, the term "first link" is used to make the description of the present invention clearer and concise.

In one possible embodiment, the first capability information may be contained in a sub-TLV of the first packet. Fig. 9 is a schematic diagram of a sub-TLV according to an embodiment of the present invention, as shown in fig. 9, a field "type value" is to be allocated by an Internet Assigned Numbers Authority (IANA) from a corresponding registry, a field "length" is set to 4, a field "BSL flag (BSL capability)" is a bitmap field of 8 bits length, and each bit specifies the capability of supporting a specific "BIER bit string length" when set as follows:

bit 1-support BSL 64

Bit 2-support BSL 128

Bit 3-support BSL 256

Bit 4-support BSL 512

Bit 5-support BSL 1024

Bit 6-support BSL 2048

Bit 7-support BSL 4096

Bit 8-reservation

In one possible embodiment, the field "BSL flag (BSL capability)" indicates the first capability information.

S802: the second node announces a first message to the first node, wherein the first message includes the first capability information.

Then, if the second node specified in this embodiment determines the first capability information, the second node advertises the 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 corresponding 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 may be assumed that router a and router B are connected by a single link (link 1). For one case, the router B advertises a first packet to the router a, the first capability information is included in the first packet, and the first capability information includes a bit of BSL 256 corresponding to an interface supporting the router B. If the BSL corresponding to the interface of the router a is 64, the router a determines that the bit contained in the first capability information does not support the BSL corresponding to the interface of the router a, and if the BSL corresponding to the interface of the router a is 256, the router a determines that the bit contained in the first capability information supports the BSL corresponding to the interface of the router a, where the interface of the router a and the interface of the router B both correspond to the link 1. For another case, the router B advertises a first packet to the router a, the first capability information is included in the first packet, and the first capability information includes bits of BSL 256 and BSL 64 corresponding to two interfaces supporting the router B. If the BSL corresponding to the interface of the router a is 128, the router a determines that the bit contained in the first capability information does not support the BSL corresponding to the interface of the router a, and if the BSL corresponding to the interface of the router a is 256 or 64, the router a determines that the bit contained in the first capability information supports the BSL corresponding to the interface of the router a, where the interface of the router a and the interface of the router B both correspond to the link 1. It should be noted that one or more bits may be included in the first capability information and are not limited to the one or two bits discussed herein.

S805: 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 establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding.

Fig. 10 is a schematic diagram of an exemplary application scenario according to an embodiment of the present invention, and as shown in fig. 10, the application scenario and topology are the same as those in fig. 5, the SPT is modified for BIER to span (bypass) a node and a link without BIER capability, and can span (bypass) a node B without BIER capability using a unicast tunnel, so the multicast traffic path from node a to node E is: [A] - (tunnel) - [ D ] - [ E ].

It should be appreciated that there is another case where the first node forwards traffic to the second node for BIER forwarding if one or more bits contained in the first capability information support a BSL corresponding to an interface of the first node.

For example, during traffic forwarding, if the first node determines that one or more bits contained in the first capability information support a BSL corresponding to an interface of the first node, which means that the second node can be used to forward traffic, the first node forwards the traffic to the second node. Traffic is data that needs to be forwarded through the network, e.g. multicast traffic in a BIER network.

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

It should be understood that there is another case that the first node excludes the second node when establishing the BIER SPT by using the SPF algorithm if one or more bits included in the first capability information do not support the BSL corresponding to the interface of the first node.

The present invention provides a method for advertising and processing BIER capabilities of a link, wherein the second node: determining first capability information including one or more bits, each Bit supporting a Bit String Length (BSL) corresponding to an interface of the second node, the interface of the second node corresponding to a first link between the second node and a first node, and then the second node advertising a first packet to the first node, wherein the first packet includes the first capability information. The first node receives a first message from a second node, determines whether one or more bits contained 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 a first link, and then establishes a tunnel between the first node and a third node to bypass the second node for BIER forwarding when the one or more bits contained in the first capability information do not support the BSL corresponding to the interface of the first node. In a scenario in which a partially BIER-capable node in a network topology is encountered during traffic forwarding, the first node determines whether to forward the traffic to the partially BIER-capable node based on the first capability information. Traffic may be forwarded even if a partially BIER-capable node in the network topology is encountered.

Fig. 11 is a schematic flow chart diagram of a second method for advertising and handling BIER capabilities of a link in accordance with an embodiment of the invention. The method shows an interaction between a first node and a second node, where both the second 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 shown in fig. 8 is that the first message further comprises second capability information.

The method comprises the following steps:

s1101: the second node determines first capability information including one or more bits, each Bit supporting 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 announces a first message to the first node, wherein the first message 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, wherein the interface of the first node corresponds to the first link.

Reference may be made to the description in S804.

S1105: when 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 determines whether the second capability information indicates that the first link supports BIER forwarding.

In one possible implementation, the second capability information may be a field in the first message, different values of which indicate whether the first link supports BIER forwarding. In one possible embodiment, the second capability information may be included in a sub-TLV, the presence of which indicates that the first link supports BIER forwarding, and if the first node receives a packet that does not include the sub-TLV, the first node determines that the first link does not support BIER forwarding.

In one possible embodiment, the first capability information and the second capability information are contained in a sub-TLV of the first packet; if the first message is an IGP OSPF LSA message, the sub-TLV is contained in an OSPF extended link opaque LSA under the OSPF extended link TLV; if the first message is an IGP ISIS LSP message, the sub-TLV is contained in TLV-22 of the first message or TLV-23 of the first message.

In the two possible embodiments, the first capability information and the second capability information may be carried in different TLVs of different protocols, and the packet may be an LSA or LSP packet, so that the technical solution may be better compatible with the existing protocol.

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

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

It should be understood that there is another case where the first node removes the second node when the BIER SPT is established by using the SPF algorithm if 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 that the first link does not support BIER forwarding.

Fig. 12 is a schematic diagram of another exemplary application scenario according to an embodiment of the present invention, and as shown in fig. 12, the application scenario and topology are the same as those in fig. 6, and the SPT of BIER is based on the limitation that links and nodes must support BIER to establish, so a link a-B without BIER capability is removed when establishing the SPT, but the SPF algorithm includes a node B in the SPT, because it can support BIER forwarding through the link C-B, so the multicast traffic path from the node a to the node E is: [A] - [ C ] - [ B ] - [ D ] - [ E ].

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

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

The present invention provides a method for advertising and processing BIER capabilities of a link, wherein the second node: determining first capability information comprising one or more bits, each bit supporting a BSL corresponding to an interface of the second node, the interface of the second node corresponding to a first link between the second node and a first node, and then the second node advertising a first packet to the first node, wherein the first packet includes the first capability information. The first node: receiving the first packet from the second node; determining whether the one or more bits included 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; then determining whether the one or more bits contained 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 finally, when the second capability information indicates that the first link supports BIER forwarding, adding the second node into a BIER SPT by using an SPF algorithm, wherein the technical scheme of the embodiment can support nodes with partial BIER capability, and forward traffic or establish SPT according to the condition of the nodes with partial BIER capability in the network, and does not need to deploy a complex IGP multi-topology technology, and the first capability information and the second capability information are considered during SPT establishment or traffic forwarding.

Fig. 13 is a structural view of a first apparatus for processing BIER capability of a link according to an embodiment of the present invention, as shown in fig. 13, wherein the apparatus includes: a receiving module 1301, a first determining module 1302 and a building 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, each bit supporting 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 device and a third node to bypass the second node for BIER forwarding when 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 device.

In an embodiment, the first packet further includes second capability information, when 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 device, the first determining module 1302 is specifically configured to determine whether the second capability information indicates that the first link supports BIER forwarding, and when the second capability information indicates that the first link does not support BIER forwarding, the establishing module 1303 is specifically configured to establish the tunnel between the device and the third node.

Fig. 14 is a structural view of a second apparatus for processing BIER capability of a link according to an embodiment of the present invention, and as shown in fig. 14, in addition to the receiving module 1301, the first determining module 1302 and the establishing module 1303, the apparatus further includes an adding module 1304, where the adding module 1304 is configured to add a second node to a BIER SPT by using an SPF algorithm when the second capability information indicates that the first link does not support BIER forwarding.

Fig. 15 is a structural view of an apparatus for advertising BIER capability of a link according to an embodiment of the present invention, as shown in fig. 15, wherein the apparatus includes: a second determination module 1501 and an announcement module 1502.

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

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

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

The present invention also provides a first apparatus for handling BIER capabilities of a link, comprising a processor and a memory. The memory stores instructions for causing the processor to perform the method according to the method described above.

The present invention also provides a second apparatus for advertising BIER capabilities for a link that includes a processor and a memory. The memory stores instructions for causing the processor to perform the method according to the method described above.

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

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

The present invention also provides a first communication node comprising means for handling the BIER capability of a link according to the above embodiments.

The present invention also provides a second communication node comprising means for advertising BIER capabilities of a link according to the above embodiments.

The terms such as "first," "second," and the like in the description and claims of the present invention and in the above drawings are intended to distinguish between different objects and are not intended to limit a particular order.

Terms such as "and/or" in embodiments of the present invention are used only to describe associations between associated objects, which indicates that three relationships may exist, e.g., A and/or B may indicate that only A is present, both A and B are present, and only B is present.

The terms "a" and "an" are not intended to specify one or a single element, but may be used to denote multiple elements, where appropriate.

In embodiments of the invention, expressions such as "exemplary" or "e.g.," are used to indicate an example or illustration of an example. Any embodiment or design described as "exemplary" or "e.g.," in an embodiment of the invention should not be construed as preferred or advantageous over other embodiments or designs. In particular, use of "exemplary" or "e.g.," is intended to present related concepts in a particular manner.

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

Fig. 16 is a schematic diagram of a hardware device 1600 that may comprise, for example, a node or functional entity of a communication system, the hardware device 1600 being configured to perform any or all of the steps of the above methods and features described herein, in accordance with various embodiments of the present invention. In some embodiments, the hardware device may be an element of a communication network infrastructure, such as a router or switch. Further, a device may include multiple instances of a component, such as multiple processors, memories, transmitters, receivers, transceivers, etc. As shown in fig. 16, hardware device 1600 includes a processor 1605, such as a Central Processing Unit (CPU), and may also include a specialized processor, 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 transceiver 1630, all of which are communicatively coupled via a bidirectional bus. Any or all of the described elements, or only a subset of the elements, may be used according to some embodiments. Further, a device may include multiple instances of certain elements, such as multiple processors, memories, or transceivers. Additionally, elements of the hardware device may be directly coupled to other elements without a bidirectional bus.

The memory 1620 may comprise 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), and the like, as well as any combination of these types. The mass storage element may comprise any type of non-transitory storage device such as a solid state drive, hard drive, magnetic disk drive, optical disk drive, U-disk, or any computer program product for storing data and machine executable program code. In some embodiments, mass storage may be integrated with heterogeneous memory. According to some embodiments, a memory or mass storage may have recorded thereon statements and instructions executable by a processor for performing any of the method steps described above.

Hardware device 1600 may include one or more network interfaces 1615, which may include at least one of a wired network interface and a wireless network interface. The network interface may include a wired network interface for connecting to a network and may also include a wireless access network interface for connecting to other devices over wireless links. When the hardware device is a network infrastructure element, the radio access network interface may be omitted for nodes or functions that are PLMN elements rather than nodes or functions at the radio edge (e.g. eNB). When hardware device 1600 is an infrastructure located at the wireless edge of a network, both wired and wireless network interfaces may be included. When hardware device 1600 is a wireless connection device, such as a user device, a radio access network interface may be present and may be supplemented by other wireless interfaces, such as a WiFi network interface. Network interfaces allow hardware device 1600 to communicate with remote entities or the like connected to a network.

According to an embodiment, video adapter and I/O interface 1625 provide an interface to couple hardware device 1600 to external input output devices. Examples of input output devices include a display coupled to a video adapter and an I/O device such as a touch screen coupled to an I/O interface. Other devices may be coupled to hardware device 1600 and more or fewer interfaces may be used. For example, the interface may be provided to the external device using a Serial interface such as Universal Serial Bus (USB) (not shown). In some embodiments, hardware device 1600 may be a stand-alone device, while in other embodiments, hardware device 1600 may be built into a router or switch.

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

By way of example, and not limitation, such computer-readable storage media can comprise 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. Further, any connection is properly termed a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source over a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wirelessly such as infrared, wireless, microwave, etc., then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless, microwave, etc., are also 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 refer to non-transitory, tangible storage media. Such disks and discs include Compact Discs (CDs), laser discs, optical discs, Digital Versatile Discs (DVDs), floppy disks and blu-ray discs, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above may also be included within the scope of computer-readable media.

The 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 structures described above or any other structure suitable for implementation of the techniques described herein. Further, in some aspects, the functionality described herein may be provided by dedicated hardware and/or software modules for encoding and decoding, or integrated in a combined codec. Furthermore, these techniques may be fully implemented by one or more circuits or logic elements.

The techniques of this disclosure may be implemented by various means or devices, including a wireless handset, an Integrated Circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described herein to emphasize functional aspects of devices for performing the disclosed techniques, but they do not necessarily need to be implemented by different hardware units. Rather, as noted above, the various units may be combined in a codec hardware unit, or provided in combination with suitable software and/or firmware through a set of interoperating hardware units, including one or more processors as described above.

Claims

1. A method for handling Bit Index Explicit Replication (BIER) capability for a link, comprising:

a first node receives a first packet from a second node, wherein the first packet includes first capability information including one or more bits, each Bit supporting 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;

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

2. The method of claim 1, wherein the first packet further includes second capability information, and wherein the method further comprises:

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 determines whether the second capability information indicates that the first link supports BIER forwarding;

the first node establishes the tunnel between the first node and the third node if the second capability information indicates that the first link does not support BIER forwarding.

3. The method of claim 2, further comprising:

if the second capability information indicates that the first link supports BIER forwarding, the first node adds the second node to a BIER Shortest Path Tree (SPT) by using a Shortest Path First (SPF) algorithm.

4. The method according to claim 2 or 3, wherein the first capability information and the second capability information are contained in a sub-TLV of the first packet;

if the First message is an Interior Gateway Protocol (IGP), an Open Shortest Path First (OSPF) routing Protocol, or a Link State Advertisement (LSA) message, the sub-TLV is included in an OSPF extended Link opaque LSA under the OSPF extended Link TLV.

5. The method according to claim 2 or 3, wherein the first capability information and the second capability information are contained in a sub-TLV of the first packet;

if the first packet is an Intermediate System to Intermediate System (ISIS) routing Protocol or Link State Protocol (LSP) packet, the sub-TLV is included in the TLV-22 or 23 of the first packet.

6. A method for advertising Bit Index Explicit Replication (BIER) capabilities of a link, comprising:

a second node determines first capability information containing one or more bits, wherein 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;

the second node announces a first message to a first node, wherein the first message includes the first capability information, and the first capability information is used for determining whether to support a BSL corresponding to an interface of the first node.

7. The method of claim 6, wherein the first packet further comprises second capability information, wherein the second capability information is used to indicate that the first link supports BIER forwarding;

the method further comprises the following steps:

the second node determining the second capability information;

the second node advertises the second capability information.

8. The method of claim 7, wherein the first capability information and the second capability information are contained in a sub-TLV of the first packet;

9. The method of claim 7, wherein the first capability information and the second capability information are contained in a sub-TLV of the first packet;

10. An apparatus for handling Bit Index Explicit Replication (BIER) capability for a link, comprising:

a receiving module, configured to receive a first packet from a second node, where the first packet includes first capability information including one or more bits, each Bit supporting 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 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;

an establishing module, configured to establish a tunnel between the device and a third node to bypass the second node for BIER forwarding when 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 device.

11. The apparatus of claim 10, wherein the first packet further comprises second capability information, and wherein the first determining module is dedicated to:

when 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, determining whether the second capability information indicates that the first link supports BIER forwarding;

the establishing module is specially used for:

when the second capability information indicates that the first link does not support BIER forwarding, establishing the tunnel between the apparatus and the third node.

12. The apparatus of claim 11, further comprising an adding module to:

when the second capability information indicates that the first link supports BIER forwarding, adding the second node to a BIER Shortest Path Tree (SPT) by using a Shortest Path First (SPF) algorithm.

13. An apparatus for advertising Bit Index Explicit Replication (BIER) capabilities for a link, comprising:

a second determining module, configured to determine first capability information including one or more bits, each Bit supporting a Bit String Length (BSL) corresponding to an interface of the apparatus, the interface of the apparatus corresponding to a first link between the apparatus and a first node;

an advertisement module, configured to advertise a first packet to a first node, where the first packet includes the first capability information, and the first capability information is used to determine whether to support a BSL corresponding to an interface of the first node.

14. The apparatus of claim 13, wherein the first packet further comprises second capability information, and wherein the second capability information is used to indicate that the first link supports BIER forwarding;

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

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