CN107770063A

CN107770063A - Message forwarding method and device

Info

Publication number: CN107770063A
Application number: CN201610682060.5A
Authority: CN
Inventors: 彭少富
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2016-08-17
Filing date: 2016-08-17
Publication date: 2018-03-06
Also published as: WO2018033060A1

Abstract

The invention provides a kind of message forwarding method and device, this method includes：First node receives message to be forwarded, wherein, the destination address of the message is section point；Above-mentioned first node searches target topology corresponding with above-mentioned message in the topology previously generated, wherein, the topology previously generated includes：First the second topology of topological sum for generating to obtain according to MRT algorithms, the 3rd topology obtained according to SPF algorithms, the topology of the first topological sum second and the 3rd topology are different each other；Above-mentioned first node searches the next-hop node for being forwarded to above-mentioned section point in above-mentioned target topology, and above-mentioned next-hop node is forwarded the packet to based on predetermined forwarding mechanism, wherein, the predetermined forwarding mechanism is used based on Segment routing forwarding mechanism of every topology per prefix sid tunnel nested mode.By the present invention, the purpose that Segment routing network is combined with MTR functions is realized.

Description

Message forwarding method and device

Technical field

The present invention relates to the communications field, in particular to a kind of message forwarding method and device.

Background technology

Quick heavy-route (the Fast Re- of maximum redundancy tree (Maximally Redundant Trees, referred to as MRT) Route, referred to as FRR) it is a kind of newer FRR technologies, it is right using two different forwarding topologys to greatest extent in the technology The link or node failure of single-point can provide 100% protection.MRT frameworks define two kinds of forwarding mechanisms, i.e. label distribution is assisted Discuss (Label Distribution Protocol, referred to as LDP) forwarding mechanism and procotol-tunnel (IP-tunnel) turns Hair mechanism.LDP forwarding mechanisms forward behavior by different labels to distinguish the topological forwarding behavior of acquiescence or MRT so that Forwarding plane, which does not make any upgrading, can support MRT-FRR.IP-tunnel forwarding mechanisms then need to waste special MRT Loopback addresses are supported to forward, and equally also cause Forwarding plane not make any upgrading and can support MRT-FRR.Compare and Speech, LDP forwarding mechanisms are more reasonable, so the acquiescence maximum redundancy tree configuration file default MRT Profile of MRT frameworks Middle use is exactly LDP forwarding mechanisms, not yet defines other MRT Profiles at present.

Segment routing technology will allow node be that message specifies its forward-path, it is rather than most short by general Path forwards, by adding in messages by the letter of the segment identification Segment ID section list Segment List correlations formed Breath, it is not necessary to be on the intermediate node status information of the maintenance per path.Segment routing primary expansion IGP is to support to notice and learn Practise Segment ID.Typically in the network of Segment routing is deployed, in this way it is no longer necessary to dispose LDP and be based on Traffic Engineering extensions RSVP (Resource ReSerVation Protocol-Traffic Extension, referred to as RSVP-TE) .In Segment routing network, it is known that FRR technologies have the unrelated loop free alternative paths (Topology of topology Independent Loop Free Alternate, referred to as TI-LFA), but the safeguard rule that TI-LFA is defined is very multiple It is miscellaneous and also immature.

MRT functions are introduced in Segment routing network to have important meaning, and still, there has been no documents so far The content of this respect, therefore, in the related art, it can not realize that Segment routing network is combined with MTR functions.

The content of the invention

The embodiments of the invention provide a kind of message forwarding method and device, at least to solve nothing present in correlation technique Method realizes the problem of Segment routing network is combined with MTR functions.

According to one embodiment of present invention, there is provided a kind of message forwarding method, including：First node receives to be forwarded Message, wherein, the destination address of the message is section point；The first node searched in the topology previously generated with Target topology corresponding to the message, wherein, the topology previously generated includes：Generated according to maximum redundancy tree MRT algorithms First obtained the second topology of topological sum, the 3rd topology obtained according to SPF SPF algorithms, first topological sum Described second topological and described 3rd topology is different each other；The first node is searched in the target topology to be used for The next-hop node of the section point is forwarded to, and the message is forwarded to by the next-hop section based on predetermined forwarding mechanism Point, wherein, the predetermined forwarding mechanism uses point based on tunnel nested mode of every topology per prefix index prefix-sid Section routing forwarding mechanism.

Alternatively, methods described also includes：The first node according to the MRT algorithms from first topology to institute State routeing and being determined in second topology into the route of the destination address for protecting the described 3rd to open up for destination address The protection of route in flutterring to the destination address is route, and determines topology corresponding to the protection route to protect topology；With/ Or, the first node according to color-coded information from first topology to termination point of a tunnel route and it is described second topology In determined into the route of termination point of a tunnel for protect in the 3rd topology to the destination address route protection route, And determine that topology corresponding to the protection route is protection topology, wherein, the termination point of a tunnel is that the first node is protection Destination address and the distant-end node selected, the distant-end node are no loop loop-free for trouble point, work as failure The first node is used to the MRT tunnel encapsulation messages of the distant-end node during generation.

Alternatively, the first node searches target topology bag corresponding with the message in the topology previously generated Include：The first node judges whether the link for being used to reach the section point in the 3rd topology breaks down； Judge in the case of not breaking down, the first node determines the 3rd topology for target topology；And/or In the case where judging failure, the first node determines the protection topology for target topology.

Alternatively, before the message to be forwarded is received, methods described also includes the first node：Described first Node generates to obtain the topology of the first topological sum second according to the MRT algorithms, and generates to obtain according to the SPF algorithms 3rd topology.

Alternatively, the first node generates to obtain the topology of the first topological sum second according to the MRT algorithms, and Generating to obtain the 3rd topology according to the SPF algorithms includes：The first node determines the MRT where the first node Island, wherein, the MRT Island are by being in same domain in the first node and with the first node Open Shortest Path First on area or same levels level other nodes OSPF or Intermediate System-to-Intermediate System Under ISIS examples after enabled Segment routing SR and maximum redundancy tree configuration file MRT profile where the first node Area or level in by the first node and other described nodes reciprocally negotiate what is formed；The first node is based on institute State MRT Island and run the MRT algorithms and generate the second topology described in first topological sum, and, based on the area or Level runs the SPF algorithms generation the 3rd topology.

Alternatively, specified in the MRT profile and use the predetermined forwarding mechanism.

Alternatively, methods described also includes at least one of：The first node is the local section of the first node Point level prefix distributes the first prefix-sid for the described first topology, and by the first prefix-sid in the MRT Flooded in domain area or level level where Island；The first node is the local node level of the first node Prefix distributes the 2nd prefix-sid for the described second topology, and by the 2nd prefix-sid in the MRT Flooded in domain area or level level where Island；The first node be the local node level of the first node and Not a node level prefix distributes the 3rd prefix-sid for the described 3rd topology, and by the 3rd prefix-sid described Flooded in all domain area or level level where first node；The first node receives described pre- on other nodes The topological prefix-sid first generated, record the topological prefix-sid previously generated on other described nodes with And by the topological prefix-sid previously generated described on other described nodes continue to be advertised to except other described nodes it Outer node.

Alternatively, the message is forwarded to the next-hop node and included by the first node：The first node is true The outgoing label of the fixed first node matched with the message；The first node encapsulates the outgoing label of the first node The next-hop node is sent to onto the message, and by the message after encapsulation.

Alternatively, the outgoing label for the first node that the first node determines to match with the message includes：Work as institute State target topology for the described 3rd it is topological when, the outgoing label of the correspondence of the first node target topology is by the first segment Point is based on purpose prefix prefix the 3rd prefix index prefix-sid corresponding to destination address and the next-hop node What SRGB was calculated.

Alternatively, the outgoing label for the first node that the first node determines to match with the message includes：Work as institute State target topology for described first it is topological or it is described second it is topological when：If the section point is the section in the MRT Island It is described when purpose prefix prefix is the node level prefix prefix of the section point corresponding to point and the destination address First node is determined as follows the outgoing label of the correspondence target topology of the first node：The first node The outgoing label of the target topology is corresponded to by node level prefix prefix of the first node based on the section point pair The prefix index prefix-sid and the next-hop node of the target topology SRGB is answered to be calculated；If second section Point is not second section for purpose prefix prefix corresponding to the node in the MRT Island or the destination address During the not a node level prefix prefix of point, the first node judges whether the next-hop node is outside the MRT Island Node；When judged result is no, the first node is determined as follows the correspondence mesh of the first node Mark the outgoing label of topology：The outgoing label of the correspondence target topology of the first node is label stack, and outer layer label is described For first node to the label of termination point of a tunnel, vpn label is label of the termination point of a tunnel to the purpose prefix prefix；Its In, the outer layer label by node level prefix prefix of the first node based on the termination point of a tunnel the correspondence target The prefix index prefix-sid of topology and the next-hop node in target topology to the termination point of a tunnel SRGB are calculated Obtain, the vpn label is by the described 3rd topological prefix of correspondence of the first node based on the purpose prefix prefix Index prefix-sid and the termination point of a tunnel SRGB are calculated；In judged result for when being, the first node passes through Following manner determines the outgoing label of the correspondence of the first node target topology：The correspondence target of the first node The outgoing label of topology is by the described 3rd topological prefix index of correspondence of the first node based on the purpose prefix prefix What the SRGB of prefix-sid and the next-hop node was calculated.

Alternatively, the first node by the outgoing label of the first node be encapsulated on the message include it is following at least One of：When the type of message of the message is Internet protocol IP message, on the IP heads of the IP messages described the in pressure The outgoing label of one node；When the type of message of the message is Segment routing SR label packets, by the SR label packets Outgoing label of the stack top tag replacement of label stack into the first node.

Alternatively, the first node determines that the outgoing label of the first node includes：When the first node and described When section point is same node, then the first node is described based on the next-hop node that target topology determines First node, the first node do not have outgoing label.

Alternatively, methods described also includes：When the first node and the section point are same node, including： When the type of message of the message is Internet protocol IP message, the first node is by the message up sending to described first The control plane of node；And/or when the type of message of the message is Segment routing SR label packets, the first node The stack top label of the label stack of the SR label packets is ejected, and continue the label stack based on the message lower floor's label or IP heads are tabled look-up forwarding.

According to another embodiment of the invention, a kind of apparatus for forwarding message is additionally provided, described device is applied to first In node, including：Receiving module, for receiving message to be forwarded, wherein, the destination address of the message is section point； Searching modul, for searching target topology corresponding with the message in the topology previously generated, wherein, it is described to previously generate Topology include：First the second topology of topological sum for generating to obtain according to maximum redundancy tree MRT algorithms, according to SPF The 3rd topology that SPF algorithms obtain, the second topological and described 3rd topology described in first topological sum are different each other； Forwarding module, for searching the next-hop node for being forwarded to the section point in the target topology, and based on pre- Determine forwarding mechanism and the message is forwarded to the next-hop node, wherein, the predetermined forwarding mechanism, which uses, to be based on per topology Per the Segment routing forwarding mechanism of prefix index prefix-sid tunnel nested mode.

Alternatively, described device also includes：Determining module, for according to the MRT algorithms from first topology to Determine to be used to protect the described 3rd into the route of the destination address in the route of the destination address and second topology The protection of route in topology to the destination address is route, and determines topology corresponding to the protection route to protect topology； And/or according to color-coded information from first topology into the route and second topology of termination point of a tunnel to tunnel Determined in the route of terminal for protecting the protection of the route in the 3rd topology to the destination address to route, and determine institute Topology corresponding to protection route is stated as protection topology, wherein, the termination point of a tunnel is that the first node is protection destination address And the distant-end node selected, it is no loop loop-free that the distant-end node, which is directed to trouble point, when an error occurs institute First node is stated to use to the MRT tunnel encapsulation messages of the distant-end node.

According to still another embodiment of the invention, a kind of storage medium is additionally provided.The storage medium is arranged to storage and used In the program code for performing above-mentioned steps.

By the present invention, MRT functions are introduced in Segment routing network, it is achieved thereby that Segment routing network and MTR work( The purpose that can be combined.

Brief description of the drawings

Accompanying drawing described herein is used for providing a further understanding of the present invention, forms the part of the application, this hair Bright schematic description and description is used to explain the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings：

Fig. 1 is the flow chart of message forwarding method according to embodiments of the present invention；

Fig. 2 is the MRT Profile schematic diagrames according to the specific embodiment of the invention；

Fig. 3 is the network topological diagram according to the specific embodiment of the invention one；

Fig. 4 is the network topological diagram according to the specific embodiment of the invention two；

Fig. 5 is the network topological diagram according to the specific embodiment of the invention three；

Fig. 6 is the structured flowchart of apparatus for forwarding message according to embodiments of the present invention；

Fig. 7 is the preferred structure block diagram of apparatus for forwarding message according to embodiments of the present invention.

Embodiment

Describe the present invention in detail below with reference to accompanying drawing and in conjunction with the embodiments.It should be noted that do not conflicting In the case of, the feature in embodiment and embodiment in the application can be mutually combined.

It should be noted that term " first " in description and claims of this specification and above-mentioned accompanying drawing, " Two " etc. be for distinguishing similar object, without for describing specific order or precedence.

A kind of message forwarding method is provided in the present embodiment, and Fig. 1 is message forwarding side according to embodiments of the present invention The flow chart of method, as shown in figure 1, the flow comprises the following steps：

Step S102, first node receive message to be forwarded, wherein, the destination address of the message is section point；

Step S104, above-mentioned first node search target topology corresponding with above-mentioned message in the topology previously generated, Wherein, the topology previously generated includes：First the second topology of topological sum for generating to obtain according to maximum redundancy tree MRT algorithms, The 3rd topology obtained according to SPF (Shortest Path First, referred to as SPF) algorithm, first topology It is different each other with the second topology and the 3rd topology；

Step S106, above-mentioned first node are searched for being forwarded to the next of above-mentioned section point in above-mentioned target topology Hop node, and above-mentioned next-hop node is forwarded the packet to based on predetermined forwarding mechanism, wherein, the predetermined forwarding mechanism uses base In Segment routing forwarding mechanism of every topology per prefix index prefix-sid tunnel nested mode.

Wherein, above-mentioned first node can be any node in MRT Island, and above-mentioned section point can be Any node in SRDomain, the section point are likely to be in the MRT Island or outside MRT Island.Above-mentioned First the second topology of topological sum can be MRT-red topologys with one, and one is MRT-blue topologys；The 3rd above-mentioned topology can be with It is MT-default topologys.

In the above-described embodiments, first node can be based on predetermined repeater-transmitter when forwarding the packet to next-hop node System is forwarded, and the predetermined forwarding mechanism is based on segmentation of every topology per Segment routing overall situation block SRGB tunnel nested mode Routing forwarding mechanism.

By above-mentioned steps, MRT functions are introduced in Segment routing network, it is achieved thereby that Segment routing network and MTR The purpose that function combines.

In an optional embodiment, the above method also includes that (sheet can be performed before message to be forwarded is received Step in embodiment)：Above-mentioned first node according to MRT algorithms from the first topology to the route of destination address and second topology In determined into the route of destination address for protect in above-mentioned 3rd topology to destination address route protection route, and really Topology corresponding to fixed above-mentioned protection route is protection topology；And/or above-mentioned first node is opened up according to color-coded information from first Flutter and determine to be used to protect in the 3rd topology to mesh into the route of termination point of a tunnel into the route of termination point of a tunnel and the second topology Address route protection route, and determine topology corresponding to above-mentioned protection route as protection topology, wherein, the termination point of a tunnel The distant-end node selected for first node for protection destination address, distant-end node are no loop loop- for trouble point Free's, above-mentioned first node is used to the MRT tunnel encapsulation messages of distant-end node when an error occurs.In the present embodiment, When it is determined that protecting topological, it may be determined that the first topology is protection topology, can also determine the second topology as protection topology, specifically Which topology is selected to need to be determined according to actual conditions as protection topology.

In an optional embodiment, above-mentioned first node is searched corresponding with above-mentioned message in the topology previously generated Target topology include：Above-mentioned first node judges whether the link for being used to reach section point in the 3rd topology event occurs Barrier；In the case where judging not break down, first node determines above-mentioned 3rd topology for target topology；And/or sentencing Break in the case of failure, above-mentioned first node determines protection topology for target topology.In the present embodiment, when link does not have When faulty, it can continue to carry out message forwarding according to the topology of acquiescence, it is necessary to use protection topology after link breaks down Carry out message forwarding.

In an optional embodiment, above-mentioned first node is before the message to be forwarded is received, the above method Also include：First node generates to obtain first the second topology of topological sum according to MRT algorithms, and generates to obtain according to SPF algorithms 3rd topology.

In an optional embodiment, above-mentioned first node generates to obtain the first topological sum according to above-mentioned MRT algorithms Two topologys, and generate to obtain the 3rd topology according to SPF algorithms and include：First node determines the MRT where above-mentioned first node Island, wherein, the MRT Island are by being in same domain area or same layer in first node and with first node Open Shortest Path First on secondary level other nodes (Open shortest Path First, referred to as OSPF) or Person's Intermediate System-to-Intermediate System (Intermediate system to Intermediate system, referred to as ISIS) is real Under example after enabled Segment routing SR and maximum redundancy tree configuration file MRT profile in the area where first node or Reciprocally negotiate what is formed by first node and other nodes in level；The first node is based on above-mentioned MRT Island operations MRT Algorithm generation the second topology of the first topological sum, and, based on the topology of above-mentioned area or level operation SPF algorithms generation the 3rd.

Specified in an optional embodiment, in above-mentioned MRT profile and use above-mentioned predetermined forwarding mechanism.That is, adopt With above-mentioned based on Segment routing forwarding mechanism of every topology per prefix index prefix-sid tunnel nested mode.

In an optional embodiment, the above method also includes at least one of：Above-mentioned first node is first segment The local node level prefix of point distributes the first prefix-sid for the first topology, and by the first prefix-sid in MRT Flooded in domain area or level level where Island；Above-mentioned first node is the local node level prefix of first node For the second topology the 2nd prefix-sid of distribution, and by the 2nd prefix-sid in the domain area where MRT Island or Flooded in level level；Above-mentioned first node is that the local node level of first node and not a node level prefix open up for the 3rd The 3rd prefix-sid of distribution is flutterred, and by the 3rd prefix-sid in all the domain area or level where first node Flooded in level；Above-mentioned first node receives the above-mentioned topological prefix-sid previously generated on other nodes, and record should The above-mentioned topological prefix-sid previously generated on other nodes and by the topology previously generated on other nodes Prefix-sid continue to be advertised to the node in addition to other nodes.In the present embodiment, above-mentioned first prefix-sid, Two prefix-sid, the 3rd prefix-sid are separate each other.

In an optional embodiment, above-mentioned first node, which forwards the packet to above-mentioned next-hop node, to be included：First Node determines the outgoing label of the first node matched with above-mentioned message；The first node encapsulates the outgoing label of above-mentioned first node Next-hop node is sent to onto above-mentioned message, and by the message after encapsulation.In the present embodiment, for different types of report Text, the packaged type of label is different.

In an optional embodiment, above-mentioned first node determines the outgoing label bag of the first node matched with message Include：When above-mentioned target topology is topological for the 3rd, the outgoing label of the corresponding target topology of above-mentioned first node is by first node base Calculated in the SRGB of purpose prefix prefix the 3rd prefix index prefix-sid and next-hop node corresponding to destination address Obtain.

In an optional embodiment, above-mentioned first node determines the outgoing label of the first node matched with above-mentioned message Including：When above-mentioned target topology is the first topology or second is topological：If above-mentioned section point is the node in MRT Island And when purpose prefix prefix corresponding to the destination address is the node level prefix prefix of section point, above-mentioned first node It is determined as follows the outgoing label of the above-mentioned target topology of correspondence of first node：The corresponding target topology of above-mentioned first node Outgoing label by node level prefix prefix of the first node based on above-mentioned section point corresponding target topology prefix index The SRGB of prefix-sid and next-hop node is calculated；If above-mentioned section point for the node in MRT Island or When purpose prefix prefix corresponding to destination address is the not a node level prefix prefix of section point, above-mentioned first node judges Whether next-hop node is node outside MRT Island；When judged result is no, first node is determined as follows The outgoing label of the above-mentioned target topology of correspondence of first node：The outgoing label of the above-mentioned target topology of correspondence of first node is label Stack, outer layer label are label of the above-mentioned first node to termination point of a tunnel, and vpn label is above-mentioned termination point of a tunnel to purpose prefix Prefix label；Wherein, the outer layer label by node level prefix prefix of the first node based on above-mentioned termination point of a tunnel pair The prefix index prefix-sid and the next-hop node in target topology to above-mentioned termination point of a tunnel of target topology SRGB is answered to count Obtain, the vpn label is by the topological prefix index prefix- of correspondence threeth of the first node based on purpose prefix prefix The SRGB of sid and termination point of a tunnel is calculated；In judged result for when being, above-mentioned first node is determined as follows first The outgoing label of the corresponding target topology of node：The outgoing label of the corresponding target topology of above-mentioned first node is based on upper by first node The prefix index prefix-sid of the topology of correspondence the 3rd and the SRGB of next-hop node for stating purpose prefix prefix are calculated 's.

In an optional embodiment, the outgoing label of above-mentioned first node is encapsulated on message and wrapped by above-mentioned first node Include at least one of：When the type of message of above-mentioned message is Internet protocol IP message, on the IP heads of above-mentioned IP messages The outgoing label of first node in pressure；When the type of message of above-mentioned message is Segment routing SR label packets, by above-mentioned SR labels Outgoing label of the stack top tag replacement of the label stack of message into first node.

In an optional embodiment, above-mentioned first node determines that the outgoing label of first node includes：When above-mentioned first When node and section point are same node, then above-mentioned first node is above-mentioned the based on the next-hop node that target topology determines One node, the first node do not have outgoing label.

In an optional embodiment, the above method also includes：When above-mentioned first node and section point are same section During point, including：When the type of message of above-mentioned message is Internet protocol IP message, above-mentioned first node is by message up sending to The control plane of one node；And/or when the type of message of above-mentioned message is Segment routing SR label packets, above-mentioned first segment Point ejects the stack top label of the label stack of SR label packets, and continues the lower floor's label or IP of the label stack based on above-mentioned message Head is tabled look-up forwarding.

With reference to specific embodiment, the present invention will be described：

In embodiments of the present invention, Segment routing is combined with MRT technologies, there is provided one kind is based on Segment routing forwarding mechanism MRT-FRR methods.In the present embodiment, a kind of MRT Profile are increased newly for MRT frameworks, using Segment routing forwarding mechanism, The topological forwarding behavior of acquiescence and MRT topology forwarding behaviors are distinguished by Segment routing forwarding mechanism.

The MRT-FRR methods based on Segment routing forwarding mechanism in the embodiment of the present invention comprise the following steps：

The first step, new MRT configuration file MRT Profile are defined, the default MRT Profile phases with acquiescence Than difference is mainly reflected in using SR-LSP based on multi-prefix-sid tunneling forwarding mechanisms.Wherein, SR-LSP refers to the LSP of Segment routing (Segment Routing, referred to as SR) type based on prefix-sid generations, with LDP LSP are similar.SR-LSP tunneling forwarding mechanisms refer to that the SR LSP in MRT topologys are saved with MRT egress Point is established for purpose node, that is, after MRT FRR switchings occur, on MRT Ingress nodes, and the SR LSP in acquiescence topology It is that tunnel is nested in the SR LSP of MRT topologys.During SR-LSP tunneling forwarding mechanisms, MRT Ingress nodes need Perceive the topologically corresponding SR labels of acquiescence that MRT Egress nodes are purpose prefix distribution.Multi-prefix-sid refers to Per topology per prefix-sid, i.e., acquiescence topology and the prefix-sid in MRT-red topologys and MRT-blue topologys are not With.

Second step, enabled in IGP area/level on each node (can be only part of nodes) under corresponding IGP examples MRT and above-mentioned new MRT Profile are supported, corresponding MRT Island are generated for above-mentioned new MRT Profile.Base Corresponding MRT-red topologys and MRT-blue topologys, corresponding MT-ID difference are generated in MRT Island operation MRT algorithms It is designated as MT-red and MT-blue.The topologically corresponding MT-ID of the acquiescence generated based on SPF algorithms can be designated as MT- in addition default。

3rd step, the IGP examples on each node of Segment routing are enabled, if also enabling MRT and supporting New MRT Profile are stated, then the MT-default prefix-sid for not being only MT-default distribution node levels are MT- Default node-sid (being usually prefix-sid corresponding to some loopback routes, similarly hereinafter), are also distributed for MT-red The MT-red prefix-sid of node level are MT-red node-sid, and the MT-blue for MT-blue distribution node levels Prefix-sid is MT-blue node-sid.These three node-sid respectively with (MT-default, prefix), (MT-red, Prefix) and (MT-blue, prefix) floods up to notice message, wherein (MT-default, prefix) can be between area Flood, still (MT-red, prefix) only floods with (MT-blue, prefix) in area.

It should be noted that the node in only above-mentioned MRT Island just needs additionally for its node level prefix to divide With MT-red node-sid and MT-blue node-sid.Not a node level prefix in MRT Island can also distribute phase The MT-red prefix-sid answered and MT-blue prefix-sid, but be not essential, it is general it is not recommended that distributing, if divided Match somebody with somebody, its corresponding list item establishes process and node level prefix list item, and to establish process be all fours；MRT Island Outer node level and not a node level prefix, need not distribute corresponding MT-red prefix-sid and MT-blue Prefix-sid, because on these prefix original advertisement node, perceived less than MRT, distribution MRT phases of not knowing where to begin The MT-red prefix-sid and MT-blue prefix-sid of pass.

4th step, source node S in MRT Island for other destination node D in Island node level prefix (being designated as D-loopback0) calculates the main next-hops of SPF and MRT-blue/red next-hops, i.e. (MT-default, D- Loopback0 the main next-hops of SPF will be included in), MRT-blue next-hops will be included in (MT-blue, D-loopback0), MRT-red next-hops will be included in (MT-red, D-loopback0).And determine it is above-mentioned MRT- on earth by MRT algorithms Blue next-hops or MRT-red next-hops protect the above-mentioned main next-hops of SPF.

MT-default SR outgoing label in the above-mentioned main next-hops of SPF is based on (MT-default, D-loopback0) phase The prefix-sid answered calculations of offset in the SRGB of next-hop node obtains；MRT-red in above-mentioned MRT-red next-hops SR outgoing label is based on (MT-red, D-loopback0) corresponding prefix-sid calculations of offset in the SRGB of next-hop node Obtain；It is corresponding that MRT-blue SR outgoing label in above-mentioned MRT-blue next-hops is based on (MT-blue, D-loopback0) Prefix-sid calculations of offset in the SRGB of next-hop node obtains.

Corresponding FTN list items will be generated according to (MT-default, D-loopback0), main NHLFE includes above-mentioned SPF master Next-hop and corresponding MT-default SR outgoing label, MRT-FRR include above-mentioned choose for protecting SPF master next for NHLFE The MRT-red next-hops or MRT-blue next-hops of jump and corresponding MRT-red SR outgoing label or MRT-blue SR outgoing label. Corresponding ILM list items are also generated according to (MT-default, D-loopback0), its MT-default SR enters label and is based on (MT- Default, prefix) corresponding prefix-sid calculations of offset in the SRGB of S nodes obtains, NHLFE and above-mentioned FTN list items It is identical.

S nodes enter label mapping (Incoming accordingly it can in addition contain be generated for (MT-red, D-loopback0) Label Map, referred to as ILM) list item, it is corresponding based on (MT-red, D-loopback0) that its MT-red SR enters label Prefix-sid calculations of offset in the SRGB of S nodes obtains, and NHLFE includes MRT-red next-hops and corresponding MT-red SR Outgoing label.Also corresponding ILM list items are generated for (MT-blue, D-loopback0), its MT-blue SR enters label and is based on (MT- Blue, D-loopback0) corresponding prefix-sid calculations of offset in the SRGB of S nodes obtains, and NHLFE includes MRT- Blue next-hops and corresponding MT-blue SR outgoing label.

5th step, source node S in MRT Island also in Island or outside Island other prefix (i.e. except All other prefix in the network beyond node level prefix residing for S in MRT Island) calculate the main next-hops of SPF and MRT-FRR backup next-hops, MRT-FRR backup next skip lists are shown as corresponding MRT Egress nodes and (are designated as E, corresponding section Point level prefix is designated as E-loopback0) and color-coded information alert be selection to the MRT-red paths of E nodes or The main next-hops of above-mentioned SPF are protected in MRT-blue paths.

It is corresponding that MT-default SR outgoing label in the above-mentioned main next-hops of SPF is based on (MT-default, prefix) Prefix-sid calculations of offset in the SRGB of next-hop node obtains；Above-mentioned MRT-FRR backups next-hop enters corresponding one Label stack：Bottom label is the MT-default SR labels that E nodes are purpose prefix distribution, that is, be based on (MT-default, Prefix) corresponding prefix-sid calculations of offset in the SRGB of E nodes obtains；Upper label be S to E MRT-blue or SR corresponding to MRT-red paths (it is MRT-blue or MRT-red paths to choose bottom according to color-coded information) enters label, i.e., Based on (MT-red, E-loopback0) or (MT-blue, E-loopback0) corresponding prefix-sid S nodes SRGB Middle calculations of offset obtains.For needed before actual forward by top layer SR enter the corresponding SR ILM list items of label lookup change into outgoing label with Direct-connected next-hop, i.e., by it is above-mentioned enter label stack be converted into outgoing label stack.

Corresponding FTN list items will be generated according to (MT-default, prefix), main NHLFE includes the main next-hops of above-mentioned SPF And corresponding MT-default SR outgoing label, standby NHLFE, which is included, is based on above-mentioned MRT Egress nodes E and its respective color mark What will information was calculated enters label stack (needing to change outgoing label stack into before being used for actual forward).According to (MT-default, Prefix corresponding ILM list items) are also generated, its MT-default SR enters label and is based on (MT-default, prefix) accordingly Prefix-sid calculations of offset in the SRGB of S nodes obtains, and NHLFE is identical with above-mentioned FTN list items.If prefix saves for S Local or direct-connected prefix is put, then does not have NHLFE information.

6th step, when failure occurs, forward IP or SR label unicast traffics along MRT paths as follows：MRT Ingress nodes are based on (MT-default, prefix) corresponding FTN list items and instruct IP messages, or ILM list items to instruct SR labels Message forwards.It is specifically divided into two kinds of situations：

1) if flow matches is corresponding to some node level (MT-default, prefix) in MRT Island FTN or ILM list items, then the top-level tab MT-default SR of SR label packets can be entered Tag switching into MRT-red or MRT- MRT-red or MRT-blue next-hops are sent to after blue SR outgoing label；Or IP messages can directly be pressed to MRT-red or MRT- MRT-red or MRT-blue next-hops are sent to after blue SR outgoing label.

2) if flow matches is FTN or ILM list items corresponding to other (MT-default, prefix), then can be by SR The top-level tab MT-default SR of label packet enter Tag switching into the MT- that MRT Egress nodes are prefix distribution Default SR labels, it is sent to after compressing to MRT-red the or MRT-blue SR outgoing label of MRT Egress nodes to MRT MRT-red the or MRT-blue next-hops of Egress nodes；Or IP messages can directly be pressed to the MR- of up to MRT Egress nodes It is sent to after red or MRT-blue SR outgoing label to MRT-red the or MRT-blue next-hops of MRT Egress nodes.

MRT Transit nodes based on the node level (MT-red, prefix) to MRT Egress or (MT-blue, Prefix) corresponding SRILM list items instruct message to forward, and continue MRT-red or MRT-blue SR entering Tag switching into MRT- MRT-red or MRT-blue next-hops are sent to after red or MRT-blue SR outgoing label.

MRT Egress node bullets fall enter label to MRT-red the or MRT-blue SR of its own after, based on lower floor (MT- Default, prefix) corresponding to the corresponding ILM list items of MT-default SR label lookups instruct message to forward, or IP report Literary head is directly based upon purpose IP forwardings after exposing.

The technical scheme in the embodiment of the present invention is described in further detail below in conjunction with the accompanying drawings：

In present embodiment, the MRT Profile in the embodiment of the present invention are illustrated first：

Fig. 2 is the MRT Profile schematic diagrames according to the specific embodiment of the invention, MRT as shown in Figure 2 Profile, it is essentially identical with the default MRT Profile defined in RFC7812, and difference is MRT Forwarding Mechanism options are SR-LSP based on multi-prefix-sid tunneling Option.

Specific embodiment one

The MRT paths forwarding process that description purpose prefix is in MRT Island by the present embodiment, Fig. 3 are according to this The network topological diagram of invention specific embodiment one, as shown in figure 3, running OSPF in network, all nodes are in same area It is interior, the MRT defined in Segment routing function and enabled the above embodiment of the present invention is enabled under corresponding OSPF examples Profile.S is established to destination node D prefix MRT paths as source node, is then based on this MRT trail protection SPF Main path.Comprise the following steps：

Enabled under OSPF examples on each nodes of step S301, S, A, B, D defined in SR and the embodiment of the present invention MRT Profile, then they a MRT Island is formed in area.And use MRT due to being specified in MRT Profile SR-LSP based on multi-prefix-sid tunneling Option are as forwarding mechanism, then in MRT Island Each node in addition to distributing MT-default prefix-sid, also additional allocation MT-red prefix-sid and MT- Blue prefix-sid, such as will can be distributed on S nodes for node level prefix S-loopback0 three kinds Prefix-sid is designated as respectively：(MT-default, S-loopback0) node-sid, (MT-red, S-loopback0) node- Sid, (MT-blue, S-loopback0) node-sid.Furthermore it is possible to the SRGB for remembering S nodes is SRGB_S, other node classes Seemingly.

The MT-default topologys that will be obtained in MRT Island on each node based on SPF algorithms in area, and be based on MRT algorithms obtain MT-red and MT-blue topologys.For example be S-D to destination node D MT-default paths on S nodes, MT-red paths are also S-D, and MT-blue paths are S-A-B-D.

The corresponding prefix list items of Topology g eneration are based on each node, such as on S nodes, to mesh in MT-default topologys Node D node level prefix D-loopback0 MT-default next-hops be D, and choose in MT-blue topologys Protect MT-default next-hops D in the MT-blue paths provided, then corresponding MRT-FRR next-hops will be copied to be above-mentioned Next-hop in MT-blue is A, referred to as MRT-blue next-hops.Assuming that (MT-default, D-loopback0) node- Sid is default_SID0_D, and (MT-red, D-loopback0) node-sid is red_SID0_D, (MT-blue, D- Loopback0) node-sid is blue_SID0_D, then outgoing label corresponding to above-mentioned MT-default next-hops D is SRGB_D [default_SID0_D], outgoing label corresponding to above-mentioned MRT-blue next-hops A are SRGB_A [blue_SID0_D].It is right below List item on part of nodes is illustrated：

S nodes：

FTN for(MT-default,D-loopback0)

Main NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID0_D]

Standby NHLFE：Next-hop is A, and outgoing label is SRGB_A [blue_SID0_D] ILM for (MT-default, D- loopback0)

It is SRGB_S [default_SID0_D] to enter label

Main NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID0_D]

Standby NHLFE：Next-hop is A, and outgoing label is SRGB_A [blue_SID0_D]

A nodes：

ILM for(MT-blue,D-loopback0)

It is SRGB_A [blue_SID0_D] to enter label

NHLFE：Next-hop is B, and outgoing label is SRGB_B [blue_SID0_D]

B node：

ILM for(MT-blue,D-loopback0)

It is SRGB_B [blue_SID0_D] to enter label

NHLFE：Next-hop is D, and outgoing label is SRGB_D [blue_SID0_D]

D nodes：

ILM for(MT-blue,D-loopback0)

It is SRGB_D [blue_SID0_D] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

Step S302, the message for being sent to destination D-loopback0, when link S-D breaks down, S nodes will As MRT ingress nodes by flow switch to preprepared MRT-blue next-hop A, that is, start message along MT- Blue paths S-A-B-D is forwarded.

If what S was received is MT-default SR label packets, it is based on ILM for (MT-default, D- Loopback0) list item forwards, and will enter label SRGB_S [default_SID0_D] and is exchanged into outgoing label SRGB_A [blue_ SID0_D]；If what S was received is IP messages, it is forwarded based on FTN for (MT-default, D-loopback0) list item, The outgoing label SRGB_A [blue_SID0_D] in pressure directly on IP heads.

It is SRGB_A [blue_SID0_D] according to the top-level tab of message after step S303, A node receives message, matching To ILM for (MT-blue, D-loopback0) list item, continue top-level tab SRGB_A [blue_SID0_D] friendships of message B is issued after changing SRGB_B [blue_SID0_D] into.

Step S304, it is SRGB_B [blue_SID0_D] according to the top-level tab of message after B node receives message, matching To ILM for (MT-blue, D-loopback0) list item, continue top-level tab SRGB_B [blue_SID0_D] friendships of message D is issued after changing SRGB_D [blue_SID0_D] into.

It is SRGB_D [blue_SID0_D] according to the top-level tab of message after step S305, D node receives message, matching To ILM for (MT-blue, D-loopback0) list item, the local SR-LSP that terminates, continue to forward based on IP heads after peeling label off, Because IP heads are D-loopback0, then message up sending control plane.

Step S306, for the not a node level prefix on D nodes, such as D-loopback1, or distribution phase The three kinds of prefix-sid answered, such as：(MT-default, D-loopback1) prefix-sid, (MT-red, D-loopback1) Prefix-sid, (MT-blue, D-loopback1) prefix-sid.And each node similar step S301 in MRT Island Establish to D-loopback1 list item, and forwarding behavior similar step S302~305, repeat no more.

Preferably, optimization method in embodiments of the present invention can be merely the node level prefix in MRT Island The corresponding MT-red node-sid of additional allocation and MT-blue node-sid.Below to each node under this optimization method How corresponding list item is established for D-loopback1 to illustrate.It will also be described in other embodiments according to this optimization method, and And assume that the loopback0prefix of each node is that node level prefix, other prefix are not a node level prefix.

It should be noted that a kind of Rule of judgment based on above-mentioned optimization method is：If prefix is the section in area Point level prefix and its advertizing node are the nodes in MRT Island, then are that the prefix establishes list item according to step S301, Otherwise S307 establishes list item in accordance with the following steps.

On step S307, S node, the MT-default next-hops in MT-default topologys to D-loopback1 are D, And the MT-blue paths (S-A-B-D) provided in MT-blue topologys are chosen to protect MT-default next-hop D, then MRT- FRR backup next-hops are MRT Egress nodes D and color-coded information is MRT-blue.Assuming that (MT-default, D- Loopback1) prefix-sid is default_SID1_D.The list item on part of nodes is illustrated below：

S nodes：

FTN for(MT-default,D-loopback1)

Main NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID1_D]

Standby NHLFE：It is SRGB_S [blue_SID0_D] that top layer, which enters label,

Bottom outgoing label is SRGB_D [default_SID1_D]

ILM for(MT-default,D-loopback1)

It is SRGB_S [default_SID1_D] to enter label

Main NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID1_D]

Standby NHLFE：It is SRGB_S [blue_SID0_D] that top layer, which enters label,

Bottom outgoing label is SRGB_D [default_SID1_D]

ILM for(MT-blue,D-loopback0)

It is SRGB_S [blue_SID0_D] to enter label

NHLFE：Next-hop is A, and outgoing label is SRGB_A [blue_SID0_D]

D nodes：

ILM for(MT-default,D-loopback1)

It is SRGB_D [default_SID1_D] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

Step S308, the message for being sent to destination D-loopback1, when link S-D breaks down, S nodes will As MRT ingress nodes by flow switch to preprepared to distal end MRT Egress nodes D MRT-blue roads Footpath, that is, start to forward message along MT-blue paths S-A-B-D.

If what S was received is MT-default SR label packets, it is based on ILM for (MT-default, D- Loopback1) list item forwards, and will enter label SRGB_S [default_SID1_D] and is exchanged into outgoing label SRGB_D [default_ SID1_D] after, SRGB_A [blue_SID0_D] is compressed, issues next-hop A；If what S was received is IP messages, it is based on FTN for (MT-default, D-loopback1) list item forwards, the outgoing label SRGB_D [default_ in pressure directly on IP heads SID1_D] after, SRGB_A [blue_SID0_D] is compressed, issues next-hop A.

The processing that step S309, A node receives message is identical with step S303.

Step S310, the processing that B node receives message are identical with step S304.

After step S311, D node receives message, continuous bullet falls label SRGB_D [blue_SID0_D] and SRGB_D [default_SID1_D], continue to forward based on IP heads, because IP heads are D-loopback0, then message up sending control plane.

According to above-described embodiment, it is known that message along MRT paths forward when, be actually along corresponding in MRT Island SR-LSP forwardings in MRT topologys, the wherein prefix of MRT Island interior nodes level are actually by MT-default SR- LSP and MT-blue or MT-red SR-LSP adhesions, and other prefix are actually to carry its MT-default SR-LSP On MT-blue the or MT-red SR-LSP to MRT Egress nodes.

Specific embodiment two

The MRT paths forwarding process that description purpose prefix is in outside MRT Island by the present embodiment, Fig. 4 are according to this The network topological diagram of invention specific embodiment two, as shown in figure 4, OSPF is run in network, it is equal comprising two area, all nodes Enable Segment routing function under corresponding OSPF examples, S, A, B, C in wherein area1 are enabled to be determined in the embodiment of the present invention The MRT Profile of justice.S is established to destination node D prefix MRT paths as source node, is then based on this MRT path Protect SPF main paths.Comprise the following steps：

Enabled SR under the OSPF examples of all nodes in step S401, area1 and area2.Each node distribution SRGB.

Enabled under the OSPF examples on each node of S, A, B, C in step S402, area1 defined in the embodiment of the present invention MRT Profile, then they a MRT Island is formed in area1.And used due to being specified in MRT Profile MRT SR-LSP based on multi-prefix-sid tunneling Option are as forwarding mechanism, then MRT Each node in Island is in addition to distributing MT-default prefix-sid, also additional allocation MT-red prefix-sid With MT-blue prefix-sid, such as will can be distributed on B node for node level prefix B-loopback0 three kinds Prefix-sid is designated as respectively：(MT-default, B-loopback0) node-sid, (MT-red, B-loopback0) node- Sid, (MT-blue, B-loopback0) node-sid.

The MT-default topologys that will be obtained on each node based on SPF algorithms in area, and obtained based on MRT algorithms MT-red and MT-blue topologys.For example be S-A to destination node A MT-default paths on S nodes, MT-blue paths Also it is S-A, and MT-red paths are S-C-B-A.

List item and embodiment one of each node for each node level prefix foundation in MRT Island in MRT Island Step S301 in for the prefix D-loopback0 list items established be all fours, and purpose IP matchings MRT The forwarding behavior of respective nodes level prefix flow is also all fours with step S302~305 in Island, no longer superfluous State.

On step S403, S node, the MT-default in MT-default topologys to prefix D-loopback0 is next Jump is C (assuming that advertizing nodes of the ABR1 as prefix D-loopback0 in area1, then use to destination node ABR1 MT-default paths determine next-hop).For prefix D-loopback0, it can be assumed that use Tunnel The distant-end node of Endpoint Selection methods (referring to RFC7812) selection is A, it is assumed that S conducts in MRT Island GADAG root, and S<<A<<B<<C<<S, then it is S-A to node A MRT-blue paths, it can be used to protect above-mentioned MT- Default next-hops C.Assuming that (MT-default, D-loopback0) prefix-sid is default_SID0_D.It is right below List item on part of nodes is illustrated：

S nodes：

FTN for(MT-default,D-loopback0)

Main NHLFE：Next-hop is C, and outgoing label is SRGB_C [default_SID0_D]

Standby NHLFE：It is SRGB_S [blue_SID0_A] that top layer, which enters label,

Bottom outgoing label is SRGB_A [default_SID0_D]

ILM for(MT-default,D-loopback0)

It is SRGB_S [default_SID0_D] to enter label

Main NHLFE：Next-hop is C, and outgoing label is SRGB_C [default_SID0_D]

Standby NHLFE：It is SRGB_S [blue_SID0_A] that top layer, which enters label,

Bottom outgoing label is SRGB_A [default_SID0_D]

ILM for(MT-blue,A-loopback0)

It is SRGB_S [blue_SID0_A] to enter label

NHLFE：Next-hop is A, and outgoing label is SRGB_A [blue_SID0_A]

A nodes：

ILM for(MT-blue,A-loopback0)

It is SRGB_A [blue_SID0_A] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

ILM for(MT-default,D-loopback0)

It is SRGB_A [default_SID0_D] to enter label

NHLFE：Next-hop is ABR3, and outgoing label is SRGB_ABR3 [default_SID0_D]

ABR3 nodes：

ILM for(MT-default,D-loopback0)

It is SRGB_ABR3 [default_SID0_D] to enter label

NHLFE：Next-hop is ABR2, and outgoing label is SRGB_ABR2 [default_SID0_D]

ABR2 nodes：

ILM for(MT-default,D-loopback0)

It is SRGB_ABR2 [default_SID0_D] to enter label

NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID0_D]

D nodes：

ILM for(MT-default,D-loopback0)

It is SRGB_D [default_SID0_D] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

Step S404, the message for being sent to destination D-loopback0, when link S-C breaks down, S nodes will As MRT ingress nodes by flow switch to preprepared to distal end MRT Egress nodes A MRT-blue roads Footpath, that is, start to forward message along MT-blue paths S-A.

If what S was received is MT-default SR label packets, it is based on ILM for (MT-default, D- Loopback0) list item forwards, and will enter label SRGB_S [default_SID0_D] and is exchanged into outgoing label SRGB_A [default_ SID0_D] after, SRGB_A [blue_SID0_A] is compressed, issues next-hop A；If what S was received is IP messages, it is based on FTN for (MT-default, D-loopback0) list item forwards, the outgoing label SRGB_A [default_ in pressure directly on IP heads SID0_D] after, SRGB_A [blue_SID0_A] is compressed, issues next-hop A.

After step S405, A node receives message, bullet falls label SRGB_A [blue_SID0_A], by lower floor label SRGB_A [default_SID0_D] issues next-hop ABR3 after being exchanged into SRGB_ABR3 [default_SID0_D].

After step S406, ABR3 node receives message, label SRGB_ABR3 [default_SID0_D] is exchanged into Next-hop ABR2 is issued after SRGB_ABR2 [default_SID0_D].

After step S407, ABR2 node receives message, label SRGB_ABR2 [default_SID0_D] is exchanged into Next-hop D is issued after SRGB_D [default_SID0_D].

After step S408, D node receives message, bullet falls label SRGB_D [default_SID0_D], is continued based on IP heads Forwarding, because IP heads are D-loopback0, then message up sending control plane.

According to above-described embodiment, it is known that message along MRT paths forward when, be actually along corresponding in MRT Island SR-LSP forwardings in MRT topologys, after leaving MRT Island, it will be forwarded along the SR-LSP in acquiescence topology.Meet FEC7812 The forwarding rule of definition.

Specific embodiment three

The MRT paths forwarding process that description purpose prefix is in outside MRT Island by the present embodiment, in particular how Realize that the cross-domain forwarding that RFC7812 is defined is regular based on SR-LSP.Fig. 5 is the network topology according to the specific embodiment of the invention three Figure, as shown in figure 5, running OSPF in network, comprising two area, all nodes enable segmentation under corresponding OSPF examples S, A, B, C in routing function, wherein area1 are enabled in MRT Profile, area2 defined in the embodiment of the present invention B, the MRT Profile defined in the similarly enabled embodiment of the present invention of E, D, F.S is established to destination node D as source node Prefix MRT paths, be then based on this MRT trail protection SPF main path.Comprise the following steps：

Enabled SR under the OSPF examples of all nodes in step S501, area1 and area2.Each node distribution SRGB.

Enabled under the OSPF examples on each node of S, A, B, C in step S502, area1 defined in the embodiment of the present invention MRT Profile, then they a MRT Island is formed in area1.And used due to being specified in MRT Profile MRT SR-LSP based on multi-prefix-sid tunneling Option are as forwarding mechanism, then MRT Each node in Island is in addition to distributing MT-default prefix-sid, also additional allocation MT-red prefix-sid With MT-blue prefix-sid, such as will can be distributed on B node for node level prefix B-loopback0 three kinds Prefix-sid is designated as respectively：(MT-default, B-loopback0) node-sid, (MT-red, B-loopback0) node- Sid, (MT-blue, B-loopback0) node-sid.

The MT-default topologys that will be obtained on each node based on SPF algorithms in area, and obtained based on MRT algorithms MT-red and MT-blue topologys.For example be S-C-B to destination node B MT-default paths on S nodes, MT-red paths Also it is S-C-B, and MT-blue paths are S-A-B.

In MRT Island in area1 each node for each node level prefix is established in MRT Island list item with For the prefix D-loopback0 list items established it is all fours in the step S301 of specific embodiment one, and purpose The forwarding behavior of respective nodes level prefix flow is also all fours with step S302~305 in IP matching MRT Island 's.Repeat no more.

Also enable under the OSPF examples on each node of B, E, D, F in step S503, area2 and determine in the embodiment of the present invention Justice MRT Profile, then they a MRT Island is also formed in area2, corresponding MT- is generated in area2 Default topologys, and MT-red and MT-blue topologys.Assuming that shortest path next-hops of the B to D in acquiescence topology is F.

In MRT Island in area2 each node for each node level prefix is established in MRT Island list item with For the prefix D-loopback0 list items established it is all fours in the step S301 of embodiment one, and purpose IP Forwarding behavior with respective nodes level prefix flow in MRT Island is also all fours with step S302~305. Repeat no more.

On step S504, S node, the MT-default in MT-default topologys to prefix D-loopback0 is next Jump is C (assuming that advertizing nodes of the ABR1 as prefix D-loopback0 in area1, then use to destination node ABR1 MT-default paths determine next-hop).For prefix D-loopback0, it is assumed that use Tunnel Endpoint The distant-end node of Selection methods (referring to RFC7812) selection is B, it is assumed that in MRT Island S as GADAG root, And S<<A<<B<<C<<S, then it is S-A-B to node B MRT-blue paths, it can be used to protect above-mentioned MT-default next Jump C.Assuming that (MT-default, D-loopback0) prefix-sid is default_SID0_D.Below on part of nodes List item is illustrated：

S nodes：

FTN for(MT-default,D-loopback0)

Main NHLFE：Next-hop is C, and outgoing label is SRGB_C [default_SID0_D]

Standby NHLFE：It is SRGB_S [blue_SID0_B] that top layer, which enters label,

Bottom outgoing label is SRGB_B [default_SID0_D]

ILM for(MT-default,D-loopback0)

It is SRGB_S [default_SID0_D] to enter label

Main NHLFE：Next-hop is C, and outgoing label is SRGB_C [default_SID0_D]

Standby NHLFE：It is SRGB_S [blue_SID0_B] that top layer, which enters label,

Bottom outgoing label is SRGB_B [default_SID0_D]

ILM for(MT-blue,B-loopback0)

It is SRGB_S [blue_SID0_B] to enter label

NHLFE：Next-hop is A, and outgoing label is SRGB_A [blue_SID0_B]

A nodes：

ILM for(MT-blue,B-loopback0)

It is SRGB_A [blue_SID0_B] to enter label

NHLFE：Next-hop is B, and outgoing label is SRGB_B [blue_SID0_B]

B node：

ILM for(MT-blue,B-loopback0)

It is SRGB_B [blue_SID0_B] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

ILM for(MT-default,D-loopback0)

It is SRGB_B [default_SID0_D] to enter label

NHLFE：Next-hop is F, and outgoing label is SRGB_F [default_SID0_D]

F nodes：

ILM for(MT-default,D-loopback0)

It is SRGB_F [default_SID0_D] to enter label

NHLFE：Next-hop is D, and outgoing label is SRGB_D [default_SID0_D]

D nodes：

ILM for(MT-default,D-loopback0)

It is SRGB_D [default_SID0_D] to enter label

NHLFE：Nothing.Represent that SR-LSP has terminated.

Step S505, the message for being sent to destination D-loopback0, when link S-C breaks down, S nodes will As MRT ingress nodes by flow switch to preprepared to distal end MRT Egress nodes B MRT-blue roads Footpath, that is, start to forward message along MT-blue paths S-A-B.

If what S was received is MT-default SR label packets, it is based on ILM for (MT-default, D- Loopback0) list item forwards, and will enter label SRGB_S [default_SID0_D] and is exchanged into outgoing label SRGB_B [default_ SID0_D] after, SRGB_A [blue_SID0_B] is compressed, issues next-hop A；If what S was received is IP messages, it is based on FTN for (MT-default, D-loopback0) list item forwards, the outgoing label SRGB_B [default_ in pressure directly on IP heads SID0_D] after, SRGB_A [blue_SID0_B] is compressed, issues next-hop A.

After step S506, A node receives message, label SRGB_A [blue_SID0_B] is exchanged into SRGB_B [blue_ SID0_B] after issue next-hop B.

Step S507, after B node receives message, bullet falls label SRGB_B [blue_SID0_B], by label SRGB_B [default_SID0_D] issues next-hop F after being exchanged into SRGB_F [default_SID0_D].

After step S508, F node receives message, label SRGB_F [default_SID0_D] is exchanged into SRGB_D Next-hop D is issued after [default_SID0_D].

After step S509, D node receives message, bullet falls label SRGB_D [default_SID0_D], is continued based on IP heads Forwarding, because IP heads are D-loopback0, then message up sending control plane.

According to above-described embodiment, it is known that message along MRT paths forward when, in the MRT Island in area1 actually It is to be forwarded along the SR-LSP in corresponding MRT topologys, and leaves area1 into after area2, will turns along the SR-LSP in acquiescence topology Hair.Meet the forwarding rule that FEC7812 is defined.

Through the above description of the embodiments, those skilled in the art can be understood that according to above-mentioned implementation The method of example can add the mode of required general hardware platform to realize by software, naturally it is also possible to by hardware, but a lot In the case of the former be more preferably embodiment.Based on such understanding, technical scheme is substantially in other words to existing The part that technology contributes can be embodied in the form of software product, and the computer software product is stored in a storage In medium (such as ROM/RAM, magnetic disc, CD), including some instructions to cause a station terminal equipment (can be mobile phone, calculate Machine, server, or network equipment etc.) perform method described in each embodiment of the present invention.

A kind of apparatus for forwarding message is additionally provided in the present embodiment, and the device is used to realize above-described embodiment and preferred reality Mode is applied, had carried out repeating no more for explanation.As used below, term " module " can realize the soft of predetermined function The combination of part and/or hardware.Although device described by following examples is preferably realized with software, hardware, or The realization of the combination of software and hardware is also what may and be contemplated.

Fig. 6 is the structured flowchart of apparatus for forwarding message according to embodiments of the present invention, and the device can apply to first segment In point, as shown in fig. 6, the device includes receiving module 62, searching modul 64 and forwarding module 66, the device is said below It is bright：

Receiving module 62, for receiving message to be forwarded, wherein, the destination address of the message is section point；Search Module 64, above-mentioned receiving module 62 is connected to, is opened up for searching target corresponding with above-mentioned message in the topology previously generated Flutter, wherein, the topology previously generated includes：Opened up according to the first topological sum second that maximum redundancy tree MRT algorithms generate to obtain Flutter, the 3rd topology obtained according to SPF SPF algorithms, the topology of the first topological sum second and the 3rd topology are each other It is different；Forwarding module 66, above-mentioned searching modul 64 is connected to, is used to be forwarded to for searching in above-mentioned target topology The next-hop node of two nodes, and above-mentioned message is forwarded to by next-hop node based on predetermined forwarding mechanism, wherein, this predetermined turn Hair mechanism is used based on Segment routing forwarding mechanism of every topology per prefix index prefix-sid tunnel nested mode.

Fig. 7 is the preferred structure block diagram of apparatus for forwarding message according to embodiments of the present invention, and (Fig. 7 is only one as shown in Figure 7 Kind example), the device is in addition to including all modules shown in Fig. 6, in addition to determining module 72, and the device is said below It is bright：

Determining module 72, be connected to above-mentioned receiving module 62, for according to above-mentioned MRT algorithms from the first topology to purpose Determine to be used to protect in above-mentioned 3rd topology to destination address into the route of destination address in the route of address and the second topology Route protection route, and determine the protection route corresponding to topology for protection topology；And/or according to color-coded information Determine to be used to protect into the route of termination point of a tunnel into the route of termination point of a tunnel and the second topology from above-mentioned first topology The protection for stating the route in the 3rd topology to destination address is route, and determines that topology corresponding to protection route is topological for protection, Wherein, the termination point of a tunnel is the distant-end node that first node selects for protection destination address, and the distant-end node is for event Barrier point is no loop loop-free, and first node is used to the MRT tunnel encapsulation messages of distant-end node when an error occurs.

In an optional embodiment, above-mentioned searching modul 64 can be in the following way in the topology previously generated Search target topology corresponding with above-mentioned message：Judge whether the link for being used to reach section point in the 3rd topology event occurs Barrier；In the case where judging not break down, determine above-mentioned 3rd topology for target topology；And/or judging occur In the case of failure, it is determined that protection topology is target topology.In the present embodiment, when the link has not failed, can continue by Message forwarding is carried out according to the topology of acquiescence, it is necessary to carry out message forwarding using protection topology after link breaks down.

In an optional embodiment, said apparatus also includes first processing module, for receiving institute to be forwarded Before stating message, generated to obtain first the second topology of topological sum according to MRT algorithms, and generate to obtain the 3rd according to SPF algorithms Topology.

In an optional embodiment, above-mentioned first processing module can be in the following way according to above-mentioned MRT algorithms Generation obtains the first topology of topological sum second, and is generated according to SPF algorithms to obtain the 3rd topology：Determine above-mentioned first node institute MRT Island, wherein, the MRT Island are by being in same domain area in first node and with first node Or enabled Segment routing SR and maximum redundancy tree are matched somebody with somebody under OSPF the or ISIS examples on same level level other nodes Reciprocally negotiated after putting file MRT profile in the area or level where first node by first node and other nodes Formed；Based on above-mentioned MRT Island operation MRT algorithm generation the second topologys of the first topological sum, and, based on above-mentioned area Or the topology of level operation SPF algorithms generation the 3rd.

In an optional embodiment, said apparatus also includes Second processing module, for performing following operation at least One of：Be the local node level prefix of first node distributes the first prefix-sid for the first topology, and by this first Prefix-sid floods in the domain area or level level where MRT Island；For the local node level of first node Prefix distributes the 2nd prefix-sid for the second topology, and by the 2nd prefix-sid in the domain where MRT Island Flooded in area or level level；Distributed for the local node level of first node and not a node level prefix for the 3rd topology 3rd prefix-sid, and by the 3rd prefix-sid in all the domain area or level level where first node it is general Flood；The above-mentioned topological prefix-sid previously generated on other nodes is received, is recorded above-mentioned advance on other nodes The topological prefix-sid of generation and the topological prefix-sid previously generated on other nodes is continued to notice To the node in addition to other nodes.In the present embodiment, above-mentioned first prefix-sid, the 2nd prefix-sid, the 3rd Prefix-sid is separate each other.

In an optional embodiment, above-mentioned forwarding module 66 can forward the packet in the following way it is above-mentioned under One hop node：It is determined that the outgoing label of the first node matched with above-mentioned message；The outgoing label of above-mentioned first node is encapsulated into State on message, and the message after encapsulation is sent to next-hop node.In the present embodiment, for different types of message, mark The packaged type of label is different.

In an optional embodiment, above-mentioned forwarding module 66 can be determined as follows matched with message The outgoing label of one node：When above-mentioned target topology is topological for the 3rd, the outgoing label of the corresponding target topology of above-mentioned first node Purpose prefix prefix the 3rd prefix index prefix-sid and next-hop section as corresponding to first node based on destination address What the SRGB of point was calculated.

In an optional embodiment, above-mentioned forwarding module 66 can be determined as follows to be matched with above-mentioned message First node outgoing label：When above-mentioned target topology is the first topology or second is topological：If above-mentioned section point is MRT Purpose prefix prefix corresponding to node and the destination address in Island is the node level prefix prefix of section point When, above-mentioned first node is determined as follows the outgoing label of the above-mentioned target topology of correspondence of first node：Above-mentioned first segment The topological outgoing label of the corresponding target of point by node level prefix prefix of the first node based on above-mentioned section point corresponding mesh The prefix index prefix-sid and next-hop node that mark topology SRGB are calculated；If above-mentioned section point is not MRT Purpose prefix prefix corresponding to node or destination address in Island is the not a node level prefix prefix of section point When, above-mentioned first node judges whether next-hop node is node outside MRT Island；When judged result is no, first segment Point is determined as follows the outgoing label of the above-mentioned target topology of correspondence of first node：The above-mentioned target of correspondence of first node is opened up The outgoing label flutterred is label stack, outer layer label be above-mentioned first node to the label of termination point of a tunnel, vpn label is above-mentioned tunnel Terminal to purpose prefix prefix label；Wherein, the outer layer label is by node level of the first node based on above-mentioned termination point of a tunnel The prefix index prefix-sid of prefix prefix corresponding target topology is next with the interior extremely above-mentioned termination point of a tunnel of target topology The SRGB of hop node is calculated, before the vpn label is by the topology of correspondence the 3rd of the first node based on purpose prefix prefix The SRGB for sewing index prefix-sid and termination point of a tunnel is calculated；In judged result for when being, above-mentioned first node passes through such as Under type determines the outgoing label of the corresponding target topology of first node：Above-mentioned first node corresponding target topology outgoing label by The prefix index prefix-sid and next-hop node of correspondence threeth topology of the first node based on above-mentioned purpose prefix prefix SRGB be calculated.

In an optional embodiment, above-mentioned forwarding module 66 can be at least one in the following way by above-mentioned first The outgoing label of node is encapsulated on message：When the type of message of above-mentioned message is Internet protocol IP message, reported in above-mentioned IP The outgoing label of the upper first node of pressure on the IP heads of text；, will when the type of message of above-mentioned message is Segment routing SR label packets Outgoing label of the stack top tag replacement of the label stack of above-mentioned SR label packets into first node.

In an optional embodiment, above-mentioned forwarding module 66 can be determined as follows the bid of first node Label：When above-mentioned first node and section point are same node, then above-mentioned first node is determined next based on target topology Hop node is above-mentioned first node, and the first node does not have outgoing label.

In an optional embodiment, said apparatus also includes the 3rd processing module, for when above-mentioned first node and When section point is same node, following operate is performed：When the type of message of above-mentioned message is Internet protocol IP message, on First node is stated by the control plane of message up sending to first node；And/or when the type of message of above-mentioned message is Segment routing During SR label packets, above-mentioned first node ejects the stack top label of the label stack of SR label packets, and continues to be based on above-mentioned report The lower floor's label or IP heads of the label stack of text are tabled look-up forwarding.

It should be noted that above-mentioned modules can be realized by software or hardware, for the latter, Ke Yitong Cross in the following manner realization, but not limited to this：Above-mentioned module is respectively positioned in same processor；Or above-mentioned modules are with any The form of combination is located in different processors respectively.

Embodiments of the invention additionally provide a kind of storage medium.Alternatively, in the present embodiment, above-mentioned storage medium can The program code for performing above-mentioned steps to be arranged to storage to be used for.

Alternatively, in the present embodiment, above-mentioned storage medium can include but is not limited to：USB flash disk, read-only storage (Read- Only Memory, referred to as ROM), it is random access memory (Random Access Memory, referred to as RAM), mobile hard Disk, magnetic disc or CD etc. are various can be with the medium of store program codes.

Alternatively, in the present embodiment, processor performs above-mentioned each step according to the program code stored in storage medium Suddenly.

Alternatively, the specific example in the present embodiment may be referred to described in above-described embodiment and optional embodiment Example, the present embodiment will not be repeated here.

By the method in the embodiment of the present invention, the Segment routing that can be filled up in correlation technique is combined with MRT technologies Breach, valuable exploration is provided for the evolution of future network.

Obviously, those skilled in the art should be understood that above-mentioned each module of the invention or each step can be with general Computing device realize that they can be concentrated on single computing device, or be distributed in multiple computing devices and formed Network on, alternatively, they can be realized with the program code that computing device can perform, it is thus possible to they are stored Performed in the storage device by computing device, and in some cases, can be with different from shown in order execution herein The step of going out or describing, they are either fabricated to each integrated circuit modules respectively or by multiple modules in them or Step is fabricated to single integrated circuit module to realize.So, the present invention is not restricted to any specific hardware and software combination.

The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the invention, for the skill of this area For art personnel, the present invention can have various modifications and variations.Within the spirit and principles of the invention, that is made any repaiies Change, equivalent substitution, improvement etc., should be included in the scope of the protection.

Claims

A kind of 1. message forwarding method, it is characterised in that including：

First node receives message to be forwarded, wherein, the destination address of the message is section point；

The first node searches target topology corresponding with the message in the topology previously generated, wherein, it is described advance The topology of generation includes：First the second topology of topological sum for generating to obtain according to maximum redundancy tree MRT algorithms, according to shortest path The 3rd topology that preferential SPF algorithms obtain, the second topological and described 3rd topology described in first topological sum each other it is each not It is identical；

The first node is searched in the target topology for being forwarded to the next-hop node of the section point, and is based on The message is forwarded to the next-hop node by predetermined forwarding mechanism, wherein, the predetermined forwarding mechanism, which uses, to be based on often opening up Flutter the Segment routing forwarding mechanism of every prefix index prefix-sid tunnel nested mode.
2. according to the method for claim 1, it is characterised in that methods described also includes：

The first node according to the MRT algorithms from first topology to the route of the destination address and described second Determined in topology into the route of the destination address for protecting in the 3rd topology to the route of the destination address Protection route, and determine that topology corresponding to the protection route is protection topology；And/or

The first node is opened up according to color-coded information from first topology to the route of termination point of a tunnel and described second Flutter into the route of termination point of a tunnel determine for protect in the 3rd topology to the destination address route protection road By, and determine that topology corresponding to the protection route is protection topology, wherein, the termination point of a tunnel is that the first node is guarantor The distant-end node for protecting destination address and selecting, the distant-end node are no loop loop-free for trouble point, when event The first node is used to the MRT tunnel encapsulation messages of the distant-end node when barrier occurs.
3. according to the method for claim 2, it is characterised in that the first node is searched in the topology previously generated and Target topology includes corresponding to the message：

The first node judges whether the link for being used to reach the section point in the 3rd topology breaks down；

In the case where judging not break down, the first node determines the 3rd topology for target topology； And/or

In the case where judging failure, the first node determines the protection topology for target topology.
4. according to the method for claim 1, it is characterised in that the first node receive the message to be forwarded it Before, methods described also includes：

The first node generates to obtain the topology of the first topological sum second according to the MRT algorithms, and according to the SPF Algorithm generates to obtain the 3rd topology.
5. according to the method for claim 4, it is characterised in that the first node generates to obtain according to the MRT algorithms The topology of first topological sum second, and generate to obtain the 3rd topology according to the SPF algorithms and include：

The first node determines the MRT Island where the first node, wherein, the MRT Island be by The first node and the opening being in the first node on same domain area or same levels level other nodes Segment routing SR and maximum redundancy tree are enabled under SPF OSPF or Intermediate System-to-Intermediate System ISIS examples After configuration file MRT profile in the area or level where the first node by the first node and it is described its He reciprocally negotiates what is formed by node；

The first node is opened up based on described in the MRT Island operations MRT algorithms generation first topological sum second Flutter, and, the SPF algorithms generation the 3rd topology is run based on the area or level.
6. according to the method for claim 5, it is characterised in that specified in the MRT profile using described predetermined turn Hair mechanism.
7. according to the method for claim 5, it is characterised in that methods described also includes at least one of：

The first node is that the local node level prefix of the first node distributes first for the described first topology Prefix-sid, and by the first prefix-sid in the domain area or level level where the MRT Island it is general Flood；

The first node is that the local node level prefix of the first node distributes second for the described second topology Prefix-sid, and by the 2nd prefix-sid in the domain area or level level where the MRT Island it is general Flood；

The first node is the local node level of the first node and not a node level prefix for the described 3rd topology point With the 3rd prefix-sid, and by the 3rd prefix-sid in all the domain area or level where the first node Flooded in level；

The first node receives the topological prefix-sid previously generated on other nodes, other described sections of record The topological prefix-sid previously generated on point and the topology that will be previously generated described on other described nodes Prefix-sid continue to be advertised to the node in addition to other described nodes.
8. according to the method for claim 1, it is characterised in that the message is forwarded to described next by the first node Hop node includes：

The first node determines the outgoing label of the first node matched with the message；

The outgoing label of the first node is encapsulated on the message by the first node, and the message after encapsulation is sent to The next-hop node.
9. according to the method for claim 8, it is characterised in that the first node determination matches described with the message The outgoing label of first node includes：

When target topology is topological for the described 3rd, the outgoing label of the correspondence target topology of the first node is by institute State first node based on purpose prefix prefix the 3rd prefix index prefix-sid corresponding to destination address with it is described next What the SRGB of hop node was calculated.
10. according to the method for claim 8, it is characterised in that the first node determines the institute matched with the message Stating the outgoing label of first node includes：

When the target topology for described first it is topological or it is described second it is topological when：

If the section point is purpose prefix corresponding to the node in the MRT Island and the destination address When prefix is the node level prefix prefix of the section point, the first node is determined as follows described first The outgoing label of the correspondence target topology of node：The outgoing label of the correspondence of the first node target topology is by described the The prefix index prefix- of node level prefix prefix of one node based on the section point correspondence target topology Sid and the next-hop node SRGB are calculated；

If the section point is not purpose prefix corresponding to the node in the MRT Island or the destination address When prefix is the not a node level prefix prefix of the section point, whether the first node judges the next-hop node For the node outside the MRT Island；

When judged result is no, the correspondence target that the first node is determined as follows the first node is opened up The outgoing label flutterred：The outgoing label of the correspondence target topology of the first node is label stack, and outer layer label is described first For node to the label of termination point of a tunnel, vpn label is label of the termination point of a tunnel to the purpose prefix prefix；Wherein, institute State the correspondence target topology of the outer layer label by node level prefix prefix of the first node based on the termination point of a tunnel Prefix index prefix-sid and target topology in be calculated to the SRGB of next-hop node of the termination point of a tunnel, The vpn label is by the described 3rd topological prefix index of correspondence of the first node based on the purpose prefix prefix Prefix-sid and the termination point of a tunnel SRGB are calculated；

In judged result for when being, the correspondence target that the first node is determined as follows the first node is opened up The outgoing label flutterred：Before the outgoing label of the correspondence target topology of the first node is based on the purpose by the first node The SRGB for sewing the prefix index prefix-sid and the next-hop node of prefix correspondence the 3rd topology is calculated 's.
11. according to the method for claim 8, it is characterised in that the first node is by the outgoing label of the first node Being encapsulated on the message includes at least one of：

When the type of message of the message is Internet protocol IP message, on the IP heads of the IP messages described first in pressure The outgoing label of node；

When the type of message of the message is Segment routing SR label packets, by the stack top of the label stack of the SR label packets Outgoing label of the tag replacement into the first node.
12. according to the method for claim 8, it is characterised in that the first node determines the bid of the first node Label include：

When the first node and the section point are same node, then the first node is based on target topology really The fixed next-hop node is the first node, and the first node does not have outgoing label.
13. according to the method for claim 1, it is characterised in that methods described also includes：

When the first node and the section point are same node, including：When the type of message of the message is interconnection During fidonetFido IP messages, control plane of the first node by the message up sending to the first node；And/or work as institute When the type of message for stating message is Segment routing SR label packets, the first node is by the label stack of the SR label packets Stack top label ejects, and continues lower floor's label of the label stack based on the message or IP heads are tabled look-up forwarding.
A kind of 14. apparatus for forwarding message, it is characterised in that applied in first node, including：

Receiving module, for receiving message to be forwarded, wherein, the destination address of the message is section point；

Searching modul, for searching target topology corresponding with the message in the topology previously generated, wherein, it is described advance The topology of generation includes：First the second topology of topological sum for generating to obtain according to maximum redundancy tree MRT algorithms, according to shortest path The 3rd topology that preferential SPF algorithms obtain, the second topological and described 3rd topology described in first topological sum each other it is each not It is identical；

Forwarding module, for searching the next-hop node for being forwarded to the section point, and base in the target topology The message is forwarded to the next-hop node in predetermined forwarding mechanism, wherein, the predetermined forwarding mechanism is used based on every Segment routing forwarding mechanism of the topology per prefix index prefix-sid tunnel nested mode.
15. device according to claim 14, it is characterised in that described device also includes：

Determining module, for according to the MRT algorithms from first topology to the route of the destination address and described Determined in two topologys into the route of the destination address for protecting in the 3rd topology to the route of the destination address Protection route, and determine it is described protection route corresponding to topology for protection topology；And/or according to color-coded information from institute State in the first topology and determine to be used to protect institute into the route of termination point of a tunnel into the route of termination point of a tunnel and second topology The protection for stating the route in the 3rd topology to the destination address is route, and determines topology corresponding to the protection route to protect Topology, wherein, the termination point of a tunnel is the distant-end node that the first node selects for protection destination address, described remote End node is no loop loop-free for trouble point, and the first node use to the distal end when an error occurs saves The MRT tunnel encapsulation messages of point.