Configurar BGP Global IPv6 sobre SRv6

Introdução

Este documento descreve o fluxo do plano de controle ao aplicar o roteamento de segmento de encapsulamento sobre IPv6 (SRv6) para a sessão unicast IPv6 do BGP.

Informações de Apoio

Consulte o Guia de Configuração de Roteamento de Segmento para Cisco ASR 9000 Series Routers, IOS XR Release 24.1.x, 24.2.x, 24.3.x, 24.4.xpara obter informações adicionais.

Topologia

A topologia usada neste documento é descrita na Figura 1. O domínio SRv6 consiste em três roteadores, todos operando no Cisco IOS-XR. A infraestrutura de base SRv6 é implementada usando IS-IS com uSID SRv6. O peering unicast BGP IPv6 é estabelecido entre os roteadores R1 e R3, enquanto o roteador R2 não participa do BGP e funciona como um roteador P nessa configuração. A interface de Loopback 6 em R1 e R3 representa um prefixo IPv6 que deve ser trocado entre os dois peers unicast IPv6 do BGP.

Figura 1. Diagrama de topologia do unicast BGP ipv6 sobre SRv6

Configuração do SRv6

Esta seção mostra a configuração dos três roteadores SRv6. O roteador R2 inclui apenas a configuração de SRv6, pois não participa do BGP.

Configuração do roteador R1

O roteador R1 faz parte do domínio SRv6 com um localizador de fc00:bb00:1::/48. Ele também funciona como um roteador unicast BGP IPv6, originando o prefixo local fc00:aa00:1::1/128. Além disso, ele estabelece o emparelhamento unicast BGP IPv6 com o roteador R3 pela infraestrutura SRv6. A configuração destacada em negrito serve como o ponto de partida para a depuração do fluxo de controle descrito neste documento e é o único disparador usado no.

interface Loopback0
 ipv4 address 10.0.0.1 255.255.255.255
 ipv6 address fc00:bb00:1::1/128
!
interface Loopback6
 ipv6 address fc00:aa00:1::1/128
!
interface TenGigE0/0/0/8
 ipv6 enable
!
router isis 1
 is-type level-1
 net 49.0000.0000.0001.00
 address-family ipv6 unicast
  metric-style wide
  segment-routing srv6
   locator MAIN
   !
  !
 !
 interface TenGigE0/0/0/8
  point-to-point
  address-family ipv6 unicast
  !
 !
!
router bgp 1
 bgp router-id 10.0.0.1
 segment-routing srv6
  locator MAIN
 !
 address-family ipv6 unicast
  segment-routing srv6
   locator MAIN
   alloc mode per-vrf
  !
  network fc00:aa00:1::1/128
 !
 neighbor fc00:bb00:3::1
  remote-as 1
  update-source Loopback0
  address-family ipv6 unicast
   encapsulation-type srv6
  !
 !
segment-routing
 srv6
  encapsulation
   source-address fc00:bb00:1::1
  !
  locators
   locator MAIN
    micro-segment behavior unode psp-usd
    prefix fc00:bb00:1::/48
   !

Configuração do roteador R2

O roteador R2 faz parte do domínio SRv6 com um localizador de fc00:bb00:2::/48. Ele não participa do BGP e funciona como um roteador P dentro dessa topologia.

interface Loopback0
 ipv4 address 10.0.0.2 255.255.255.255
 ipv6 address fc00:bb00:2::1/128
!
interface TenGigE0/0/0/0
 description TO R1
 ipv6 enable
!
interface TenGigE0/0/0/1
 description TO R2
 ipv6 enable
!
router isis 1
 is-type level-1
 net 49.0000.0000.0002.00
 address-family ipv6 unicast
  metric-style wide
  segment-routing srv6
   locator MAIN
   !
  !
 !
 interface TenGigE0/0/0/0
  point-to-point
  address-family ipv6 unicast
  !
 !
 interface TenGigE0/0/0/1
  point-to-point
  address-family ipv6 unicast
  !
 !
!
segment-routing
 srv6
  encapsulation
   source-address fc00:bb00:2::1
  !
  locators
   locator MAIN
    micro-segment behavior unode psp-usd
    prefix fc00:bb00:2::/48
   !

Configuração do roteador R3

O roteador R3 faz parte do domínio SRv6 com um localizador de fc00:bb00:3::/48. Ele tem peering unicast IPv6 BGP com o roteador R1 e ambos trocam os prefixos IPv6 de suas interfaces Loopback 6.

interface Loopback0
 ipv4 address 10.0.0.3 255.255.255.255
 ipv6 address fc00:bb00:3::1/128
!
interface Loopback6
 ipv6 address fc00:aa00:3::3/128
!
interface TenGigE0/0/0/1
 description TO R2
 ipv6 enable
!
router isis 1
 is-type level-1
 net 49.0000.0000.0003.00
 address-family ipv6 unicast
  metric-style wide
  segment-routing srv6
   locator MAIN
   !
  !
 !
 interface TenGigE0/0/0/1
  point-to-point
  address-family ipv6 unicast
  !
 !
!
router bgp 1
 bgp router-id 10.0.0.3
 segment-routing srv6
  locator MAIN
 !        
 address-family ipv6 unicast
  segment-routing srv6
   locator MAIN
   alloc mode per-vrf
  !
  network fc00:aa00:3::3/128
 !
 neighbor fc00:bb00:1::1
  remote-as 1
  update-source Loopback0
  address-family ipv6 unicast
   encapsulation-type srv6
  !
 !
segment-routing
 srv6
  encapsulation
   source-address fc00:bb00:3::1
  !
  locators
   locator MAIN
    micro-segment behavior unode psp-usd
    prefix fc00:bb00:3::/48
   !
  !
 !        
!

Fluxo de sinalização de SID SRv6

Na infraestrutura SRv6 subjacente, cada roteador tem informações de estado de link em toda a topologia, cada qual anunciando seu localizador SRv6 através do protocolo ISIS de estado de link. O banco de dados ISIS em R1 mostra o localizador de todos os roteadores que participam do domínio SRv6.

RP/0/RSP0/CPU0:R1#show isis database verbose R1 | include SRv6 Locator
  SRv6 Locator:   MT (IPv6 Unicast) fc00:bb00:1::/48 D:0 Metric: 1 Algorithm: 0

RP/0/RSP0/CPU0:R1#show isis database verbose R2 | include SRv6 Locator
  SRv6 Locator:   MT (IPv6 Unicast) fc00:bb00:2::/48 D:0 Metric: 0 Algorithm: 0

RP/0/RSP0/CPU0:R1#show isis database verbose R3 | include SRv6 Locator
  SRv6 Locator:   MT (IPv6 Unicast) fc00:bb00:3::/48 D:0 Metric: 1 Algorithm: 0

Essa implementação de SRv6 suporta a sobreposição de tráfego da Tabela de Roteamento Global (GRT). Quando o serviço de sobreposição global de BGP IPv6 unicast está habilitado em R1 e R3, cada roteador gera um novo SID de serviço. Este SID de serviço está associado ao VRF padrão e utiliza o comportamento de endpoint uDT6 neste cenário. Este SID de serviço deve ser trocado entre pares unicast IPv6 BGP para habilitar o encaminhamento de SRv6 entre os dois pares BGP. A próxima seção descreve as etapas do fluxo de sinalização BGP, começando pela execução do disparador (habilitando o encapsulation-type srv6) até o ponto em que o encaminhamento de SRv6 é programado no Roteador R3.

1. Estado Antes de Habilitar o Encapsulamento de SRv6

Antes de habilitar o encapsulamento SRv6 no SAFI unicast IPv6 para o par BGP, o Roteador R1 deve ter prefixos BGP IPv6 com SIDs de serviço atribuídos. Isso ocorre quando 'segment-routing srv6' está habilitado no SAFI global unicast IPv6 em R1. A saída mostra o SID local fc00:bb00:1:e002:: é atribuído a todos os prefixos em unicast BGP ipv6.

RP/0/RSP0/CPU0:R1#show bgp ipv6 unicast local-sids 

BGP router identifier 10.0.0.1, local AS number 1
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 7
BGP table nexthop route policy: 
BGP main routing table version 7
BGP NSR Initial initsync version 7 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Local Sid                                   Alloc mode   Locator
*> fc00:aa00:1::1/128 fc00:bb00:1:e002::                          per-vrf       MAIN
*>ifc00:aa00:3::3/128 NO SRv6 Sid                                 -            -

Processed 2 prefixes, 2 paths

Este SID de serviço é programado localmente pelo processo sid_mgr em R1, que tem o comportamento de endpoint como uDT6, que é associado ao vrf padrão e de propriedade do bgp. Isso significa simplesmente sempre que o pacote de recebimento de R1 com endereço destino corresponde ao serviço SID fc00:bb00:1:e002:: e for o último segmento, o R1 deve desencapsular o cabeçalho e enviar o pacote desencapsulado para a pesquisa FIB da tabela vrf padrão IPv6. Isso é de acordo com o RFC8986, que lista todos os comportamentos de endpoint SRv6. Observe a saída onde ele mostra o sid_mgr create the service SID fc00:bb00:1:e002:: e passe essas informações para a RIB e, eventualmente, para a FIB.

RP/0/RSP0/CPU0:R1#show segment-routing srv6 sid all

*** Locator: 'MAIN' *** 

SID                         Behavior          Context                           Owner               State  RW
--------------------------  ----------------  --------------------------------  ------------------  -----  --
fc00:bb00:1::               uN (PSP/USD)      'default':1                       sidmgr              InUse  Y 
fc00:bb00:1:e001::          uA (PSP/USD)      [Te0/0/0/8, Link-Local]:0         isis-1              InUse  Y 
fc00:bb00:1:e002::          uDT6              'default'                         bgp-1               InUse  Y 

RP/0/RSP0/CPU0:R1#show segment-routing srv6 sid fc00:bb00:1:e002:: internal 

*** Locator: 'MAIN' *** 

SID                         Behavior          Context                           Owner               State  RW
--------------------------  ----------------  --------------------------------  ------------------  -----  --
fc00:bb00:1:e002::          uDT6              'default'                         bgp-1               InUse  Y 
  SID Function: 0xe002
  SID context: { table-id=0xe0800000 ('default':IPv6/Unicast) }
    App data: [0000000000000000]
  Locator: 'MAIN'
  Allocation type: Dynamic
  Owner List:
     1) Name: bgp-1, Client-ID: 32, Proto-ID: 8, Node-ID: 0, Locator-ID: 5 ()
  Refcount: 1
  Flags: 0x0 ()
  Chkpt Obj ID: 0x2f60
  TI Object:
    Type: Entry
    Ptr: 0x140160285526000, Producer ID: 0
    Flags: 
      Generic:  0x0 ()
      Specific: 0x0 ()
    Modified: Fri Jun 27 16:27:05 EST 2025 (2d01h ago)
  Created: Jun 27 16:17:40.796 (2d01h ago)
  Event history:
    SIDMGR-OPCODE-EVENT-CLASS
    Total entries : 4
    +---------------------------------+----------------------+------+
    | Event                           |     Time Stamp       | S, M |
    +---------------------------------+----------------------+------+
    | object create                   | Jun 27 16:17:40.864  | 1, 0 |
    | object delete                   | Jun 27 16:27:04.320  | 1, 1 |
    | object modify                   | Jun 27 16:27:04.320  | 0, 1 |
    | object refcount decrement       | Jun 27 16:27:04.320  | 0, 1 |
    +---------------------------------+----------------------+------+
RP/0/RSP0/CPU0:R1#show route ipv6 fc00:bb00:1:e002:: detail  

Routing entry for fc00:bb00:1:e002::/64
  Known via "local-srv6 bgp-1", distance 0, metric 0, SRv6 Endpoint uDT6, SRv6 Format f3216
  Installed Jun 27 16:27:06.040 for 2d01h
  Routing Descriptor Blocks
    directly connected
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      NHID: 0x0 (Ref: 0)
  Route version is 0x15 (21)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_LOCAL (3) SVD Type RIB_SVD_TYPE_LOCAL
  Download Priority 0, Download Version 3140327
  No advertising protos. 

RP/0/RSP0/CPU0:R1#show cef ipv6 fc00:bb00:1:e002::
fc00:bb00:1:e002::/64, version 3140327, SRv6 Endpoint uDT6, internal 0x1000001 0x0 (ptr 0x7bb98f54) [1], 0x400 (0x7ba7cfa0), 0x0 (0x7a90d290)
 Updated Jun 27 16:27:06.043
 Prefix Len 64, traffic index 0, precedence n/a, priority 0
  gateway array (0x78e92608) reference count 3, flags 0x0, source rib (7), 0 backups
                [4 type 3 flags 0x8401 (0x78f35598) ext 0x0 (0x0)]
  LW-LDI[type=3, refc=1, ptr=0x7ba7cfa0, sh-ldi=0x78f35598]
  gateway array update type-time 1 Jun 26 15:54:48.345
 LDI Update time Jun 26 15:54:48.349
 LW-LDI-TS Jun 27 16:17:42.533
 Accounting: Disabled
   via ::/128, 0 dependencies, weight 0, class 0 [flags 0x0]
    path-idx 0 NHID 0x0 [0x781b61e8 0x0]
    next hop ::/128

    Load distribution: 0 (refcount 4)

    Hash  OK  Interface                 Address
    0     Y   recursive                 Lookup in table

Como R1 não habilitou o encapsulamento de SRv6 em seu par unicast BGP ipv6, R1 anuncia esses prefixos em direção a R3 sem TLV SRv6 na atualização de BGP, embora R1 tenha atribuído localmente SIDs locais.

RP/0/RSP0/CPU0:R1#show bgp ipv6 unicast 

BGP router identifier 10.0.0.1, local AS number 1
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 7
BGP table nexthop route policy: 
BGP main routing table version 7
BGP NSR Initial initsync version 7 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> fc00:aa00:1::1/128 ::                       0         32768 i
*>ifc00:aa00:3::3/128 fc00:bb00:3::1           0    100      0 i

Processed 2 prefixes, 2 paths

RP/0/RSP0/CPU0:R1#show bgp ipv6 unicast advertised neighbor fc00:bb00:3::1   

fc00:aa00:1::1/128 is advertised to fc00:bb00:3::1
  Path info:
    neighbor: Local           neighbor router id: 10.0.0.1
    valid  local  best  
Received Path ID 0, Local Path ID 1, version 4
  Attributes after inbound policy was applied:
    next hop: ::
    MET ORG AS 
    origin: IGP  metric: 0  
    aspath: 
  Attributes after outbound policy was applied:
    next hop: fc00:bb00:1::1
    MET ORG AS 
    origin: IGP  metric: 0  
    aspath: 

O roteador R3 recebe a atualização do roteador R1 sem SID. O R3 instala os prefixos recebidos de R1 para sua tabela RIB e FIB sem um cabeçalho SRv6.

RP/0/RSP0/CPU0:R3#show bgp ipv6 unicast received-sids 

BGP router identifier 10.0.0.3, local AS number 1
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 44
BGP table nexthop route policy: 
BGP main routing table version 44
BGP NSR Initial initsync version 6 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop                            Received Sid
*>ifc00:aa00:1::1/128 fc00:bb00:1::1                      NO SRv6 Sid
*> fc00:aa00:3::3/128 ::                                  NO SRv6 Sid

Processed 2 prefixes, 2 paths

RP/0/RSP0/CPU0:R3#show route ipv6 unicast fc00:aa00:1::1/128 detail 

Routing entry for fc00:aa00:1::1/128
  Known via "bgp 1", distance 200, metric 0, type internal
  Installed Jun  8 17:34:24.126 for 00:12:38
  Routing Descriptor Blocks
    fc00:bb00:1::1, from fc00:bb00:1::1
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      NHID: 0x0 (Ref: 0)
      Path Grouping ID: 1
  Route version is 0x1d (29)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_RECURSIVE (12) SVD Type RIB_SVD_TYPE_LOCAL
  Download Priority 4, Download Version 162
  No advertising protos. 

RP/0/RSP0/CPU0:R3#show cef ipv6 fc00:aa00:1::1/128

fc00:aa00:1::1/128, version 162, internal 0x5000001 0x40 (ptr 0x7941f0f4) [1], 0x0 (0x0), 0x0 (0x0)
 Updated Jun  8 17:34:24.128
 Prefix Len 128, traffic index 0, precedence n/a, priority 4
  gateway array (0x78eac518) reference count 1, flags 0x2010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x78f4f538) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Jun  8 17:34:24.129
 LDI Update time Jun  8 17:34:24.129

  Level 1 - Load distribution: 0
  [0] via fc00:bb00:1::1/128, recursive

 Accounting: Disabled
   via fc00:bb00:1::1/128, 5 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x7941edb4 0x0]
    next hop fc00:bb00:1::1/128 via fc00:bb00:1::/48

    Load distribution: 0 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   TenGigE0/0/0/1            remote

2. Habilitar Encapsulamento SRv6

Habilitar o encapsulamento de SRv6 faz com que R1 envie uma mensagem de atualização de BGP para seu peer com o tipo de atributo 40, que é usado no roteamento de segmento para anunciar um prefixo de BGP com um identificador de roteamento de segmento (SID) específico. O roteador R1 envia a ATUALIZAÇÃO ao R3 para o prefixo IPv6 fc00:bb00:3::1 (Etapa 1) com o SID associado fc00:bb00:1:e002::. Ao receber a ATUALIZAÇÃO, o Roteador R3 atualiza sua tabela unicast BGP IPv6 (Etapa 2) e subsequentemente atualiza suas tabelas RIB e FIB (Etapa 3). A figura 2 ilustra o fluxo de sinalização do BGP junto com as etapas correspondentes.

Figura 2. Fluxo de sinalização BGP após a ativação do encapsulamento srv6

A saída exibe o log de depuração de BGP imediatamente após a habilitação do encapsulamento de SRv6 no peer de R3, mostrando que R1 envia uma mensagem de atualização de BGP para R3:

router bgp 1
 neighbor fc00:bb00:3::1
  address-family ipv6 unicast
   encapsulation-type srv6
  !
 !
!
end

RP/0/RSP0/CPU0:R1(config)#commit
bgp[1100]: [default-upd] (ip6u): Added reference to table TBL:default (2/1) refcount 9
bgp[1100]: [default-upd] (ip6u): Created update group for table TBL:default (2/1), index 0.3 neighbor fc00:bb00:3::1
bgp[1100]: [default-upd] (ip6u): Removed neighbor fc00:bb00:3::1 from update group 0.2 for IPv6 Unicast
bgp[1100]: [default-upd] (ip6u): Removing neighbor fc00:bb00:3::1 from update filter-group 0.2 in IPv6 Unicast sub-group 0.2 in updgrp 0.2
bgp[1100]: [default-upd]: Enqueue Wdw: Nbr:fc00:bb00:3::1(5) Wdw:0 Del:0 Pending:0 RefreshPending:0
bgp[1100]: [default-upd]: Deleting filter-group 0.2 in TBL:default (2/1) refcount 2
bgp[1100]: [default-upd] (ip6u): Deleted update group 0.2
bgp[1100]: [default-upd] (ip6u): Added reference to table TBL:default (2/1) refcount 10
bgp[1100]: [default-upd]: Compute RT set for vrf default neighbor fc00:bb00:3::1 from old filter-group 0.2 rtset 0in subgrp 0.2
bgp[1100]: [default-upd]: Allocating filter-group 0.3in TBL:default (2/1)
bgp[1100]: [default-upd] (ip6u): Added reference to table TBL:default (2/1) refcount 11
bgp[1100]: [default-upd] (ip6u): Adding vrf default neighbor fc00:bb00:3::1 to new filter-group 0.3 in IPv6 Unicast sub-group 0.1 rtset size 0 in updgrp 0.3
bgp[1100]: [default-upd] (ip6u): Added vrf default neighbor fc00:bb00:3::1 to update filter-group 0.3 in IPv6 Unicast sub-group 0.1
bgp[1100]: [default-upd] (ip6u): Added neighbor fc00:bb00:3::1 to update sub-group 0.1 in IPv6 Unicast update-group 0.3 bgp[1100]: [default-upd] (ip6u): Added vrf default neighbor fc00:bb00:3::1 to update group 0.3 for IPv6 Unicast bgp[1100]: [default-upd] (ip6u): Removed reference to Table TBL:default (2/1) refcount 10
bgp[1100]: [default-upd] (ip6u): Started updgrp timer for updgrp 0.3:: delay=0.010, delaytype=0
bgp[1100]: [default-upd] (ip6u): Removed reference to Table TBL:default (2/1) refcount 9
bgp[1100]: [default-upd] (ip6u): Starting updgen walk for updgrp 0.3:: targetver=27:  tblver=27, labelver=27, minfwdver=27, ackdfwdver=27, standbyver=0
bgp[1100]: [default-upd] (ip6u): Computing updates for update sub-group 0.1 (Regular)
bgp[1100]: [default-upd] (ip6u): bgp_srv6_execute_sid_alloc_mode_policy: Use default SRv6 alloc mode per-vrf as policy NOT in use/configured for net  and table TBL:default (2/1)
bgp[1100]: [default-upd]: table-attr walk for table TBL:default (2/1), resume version 0, subgrp version 0, target version 27
bgp[1100]: [default-upd] (ip6u): process UPDATE for: tbl=TBL:default (2/1), afi=5: ug=0.3, (Regular), pelem (Regular), sg=0.1, ugfl=0x00104183: bgpctxfl=0x00, tblctxfl=0x10000021, ltblctxfl=0x10000021, sendlab=0: net=fc00:aa00:1::1/128, nver=24: PELEM=0x7f4566d78f60 (lpathid=1, ver=24, fl=0x00000001): PATH=0x7f4566ee3eb8 (::/128,::,0, 0x20000000010401a3)::: allowbe=0, isbe=0, allowspurwdr=0, pelem-send=1, pelem-wdr=0, netExtflag=21000000
bgp[1100]: [default-upd] (ip6u): Ran 'internal' policy '(null)', result 'TRUE', ptr 0x7f4584005f30, use (nil)
bgp[1100]: [default-upd] (ip6u):     : tbl=TBL:default (2/1), afi=5: ug=0.3, sg=0.1, ugfl=0x00104183: net=fc00:aa00:1::1/128, PELEM=0x7f4566d78f60(lpathid=1, fl=0x00000001), PATH=0x7f4566ee3eb8(::/128,::,0, 0x20000000010401a3), reflected=0, bmsgfl=0x00000000, wdr=0::: netlab=0/0, pathlab=1048577, updlab=
bgp[1100]: [default-upd] (ip6u):     <NH&LABEL-SEL>: tbl=TBL:default (2/1), afi=5: ug=0.3, sg=0.1, ugfl=0x00104183+0x00001022: net=fc00:aa00:1::1/128, netlab=0/0, PELEM=0x7f4566d78f60(lpathid=1, fl=0x00000001), PATH=0x7f4566ee3eb8(::/128,::,0, 0x20000000010401a3), pathlab=1048577, reflected=0, bmsgfl=0x00000000::: pelemwdr=0, isnhself=1, enforcenhself=0, nhselectdone=0, nhcfgeval=1, updnh=0x00000000, nhlen=16, nhif=0x00000000, nh3rdp=0
bgp[1100]: [default-upd] (ip6u):     <nh&label-sel>::: labselectdo=1, labselectdone=0, updlab=1048577(0x00100001)
bgp[1100]: [default-upd]: Comm-lib: Assigned ID (0x1d000008) for elem-type PREFIX_SID SRV6_L3SVC 
bgp[1100]: [default-upd]: Comm-lib: Assigned ID (0x900000c) for elem-type Attribute 
bgp[1100]: [default-upd] (ip6u): Permit UPDATE to filter-group 0.3 (Regular, pelem Regular) for fc00:aa00:1::1/128 (changedfl=0x0/0x0), path 
bgp[1100]: [default-upd] (ip6u): Sending UPDATE message(0x0x7f4589fd4ba4) to sub-group 0.1 (Regular, pelem Regular) for fc00:aa00:1::1/128 (changedfl=0x0/0x0) -  creating new message with bmsgflags=0x00000000, attributes: nexthop ::, originator 0.0.0.0
bgp[1100]: [default-upd] (ip6u): origin i, path , metric 0, localpref 100, Prefix-SID attribute 0x05002200 0x01001e00 0xfc00bb00 0x0001e002 0x00000000 0x00000000 0x00003e00 0x01000620 0x10100000 0x0000
bgp[1100]: [default-upd] (ip6u): Created msg elem 0x0x7f4589e3afc8 (pointing to message 0x0x7f4589fd4ba4), for filtergroup 0.3
bgp[1100]: [default-upd] (ip6u): process UPDATE for: tbl=TBL:default (2/1), afi=5: ug=0.3, (Regular), pelem (Regular), sg=0.1, ugfl=0x00104183: bgpctxfl=0x00, tblctxfl=0x10000021, ltblctxfl=0x10000021, sendlab=0: net=fc00:aa00:3::3/128, nver=27: PELEM=0x7f4566d78d30 (lpathid=1, ver=27, fl=0x00000001): PATH=0x7f4566ee3d98 (fc00:bb00:3::1/128,fc00:bb00:3::1,0, 0x2000000001060005)::: allowbe=0, isbe=0, allowspurwdr=0, pelem-send=1, pelem-wdr=0, netExtflag=20000000
bgp[1100]: [default-upd] (ip6u): No unreachable (not advertising to sender: fc00:bb00:3::1) sent to sub-group 0.1 (Regular) with fc00:aa00:3::3/128 - already withdrawn
bgp[1100]: [default-upd] (ip6u): Generated 1 updates for update sub-group 0.1 (average size = 126 bytes, maximum size = 126 bytes)
bgp[1100]: [default-upd] (ip6u): Updates replicated to neighbor fc00:bb00:3::1
bgp[1100]: [default-iowt]: fc00:bb00:3::1 send UPDATE length (incl. header) 126
bgp[1100]: [default-iowt]: Send message dump for fc00:bb00:3::1:
bgp[1100]: [default-iowt]: ffff ffff ffff ffff ffff ffff ffff ffff 
bgp[1100]: [default-iowt]: 007e 0200 0000 6790 0e00 2600 0201 10fc 
bgp[1100]: [default-iowt]: 00bb 0000 0100 0000 0000 0000 0000 0100 
bgp[1100]: [default-iowt]: 80fc 00aa 0000 0100 0000 0000 0000 0000 
bgp[1100]: [default-iowt]: 0140 0101 0040 0200 8004 0400 0000 0040 
bgp[1100]: [default-iowt]: 0504 0000 0064 c028 2505 0022 0001 001e 
bgp[1100]: [default-iowt]: 00fc 00bb 0000 01e0 0200 0000 0000 0000 
bgp[1100]: [default-iowt]: 0000 003e 0001 0006 2010 1000 0000  
bgp[1100]: [default-iowt]: bgp_io_nbr_add_version: New ver: nbr=fc00:bb00:3::1, io_wr_txsn=58992, acksn=58866: ver=27 <58992>, osver=2
bgp[1100]: [default-iowt]: bgp_io_nbr_derive_acked_version: nbr=fc00:bb00:3::1, io_wr_txsn=58992, acksn=58866, osver=2
bgp[1100]: [default-iowt]: fc00:bb00:3::1 (afi:4) advancedpeer_acked_version to 10refresh peer acked version to 0
bgp[1100]: [default-iowt]: fc00:bb00:3::1 (afi:5) received ack for version 27
bgp[1100]: [default-iowt]: bgp_write_list_tonet: IO_SENDMSG: nbr=fc00:bb00:3::1, fd=530: total=1, send-attempt=1 (size 126), sent-successful=1: res=0  allmsg_adv_count = 1 msg 0x7f4589fd4ba4 bmsg_nbr_count  0 
bgp[1100]: [default-iowt] (ip6u): Deleting msg elem 0x0x7f4589e3afc8 (message 0x0x7f4589fd4ba4), for filtergroup 0.3
bgp[1100]: [default-iowt] (ip6u): Deleting message 0x0x7f4589fd4ba4, from subgroup 0.1
bgp[1100]: [default-iowt]: Keepalive timer started for fc00:bb00:3::1(loc 10): last 529293 this 529308
bgp[1100]: [default-iowt]: bgp write for afi 4 for neighbor fc00:bb00:3::1 (fd 530)
bgp[1100]: [default-iowt]: bgp write for afi 5 for neighbor fc00:bb00:3::1 (fd 530)
bgp[1100]: [default-iowt]: bgp_io_nbr_derive_acked_version: nbr=fc00:bb00:3::1, io_wr_txsn=58992, acksn=58866, osver=1
bgp[1100]: [default-iowt]: fc00:bb00:3::1 (afi:4) advancedpeer_acked_version to 10refresh peer acked version to 0
bgp[1100]: [default-iowt]: fc00:bb00:3::1 (afi:5) advancedpeer_acked_version to 27refresh peer acked version to 0
bgp[1100]: [default-iowt]: bgp_io_write_nbr_ver_timer_process: nbr_ver_timer handler: Walk complete: nbrcount=1, synctrigger=1

A saída exibe a entrada de rastreamento de BGP em R1:

default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:7799: trying to find update group for nbr fc00:bb00:3::1, afi IPv6 Unicast
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:6752: created update group for table TBL:default (2/1), index 0.3, nbr fc00:bb00:3::1, flags 0x104183
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:2039: Filter-group op (Filter-group Rm Nbr) Tbl/Nbr(Afi:IPv6 Unicast:Nbr:fc00:bb00:3::1) fgrp idx 0.2 subgrp idx 0.2 updgrp 0.2 rtset 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:1501: Filter-group op (Delete) Tbl/Nbr(TBL:default (2/1)) fgrp idx 0.2 subgrp idx 0.2 updgrp 0.0 rtset 2
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:6798: Delete update group for table TBL:default (2/1), index 0.2
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:2181: Filter-group op (Filter-group Compute Nbr RT) Tbl/Nbr(fc00:bb00:3::1) fgrp idx 0.2 subgrp idx 0.2 updgrp 0.3 rtset 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:1411: Filter-group op (Alloc) Tbl/Nbr(TBL:default (2/1)) fgrp idx 0.3 subgrp idx 0.1 updgrp 0.0 rtset 3
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:2725: Filter-group op (Filter-group Add Nbr new) Tbl/Nbr(Afi:IPv6 Unicast:Vrf:default:Nbr:fc00:bb00:3::1) fgrp idx 0.3 subgrp idx 0.1 updgrp 0.3 rtset 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:2751: created filtergrp 3 for vrf default nbr fc00:bb00:3::1, afi 5, subgrp version 0, refresh 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:4473: Created subgrp:1(0x840070a0) refr:0 for nbr fc00:bb00:3::1 (vrf default), afi 5  version 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:6935: added vrf default nbr fc00:bb00:3::1 to update group 0.3, afi IPv6 Unicast, flags 0x104183
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:3088: TBL:default (2/1) free subgrp SG:2 subgrp:0x84007440
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:1316: Update gen Start bit operation Filtergrp delete-timer fgrp idx/size 2
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:11342: Updgen - TBL:default (2/1) UG: 0.3 SG: 0.1 msg: 1
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:11344: Updgen - pfx: [tot]  adv/wdn/sup/skp/be[2] 1/0/0/1/0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:11351: Updgen - fpx: wdn/skp[0/0] ver: 0 -> 27 res ver: 0 -> 27
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:4009: Updgen - UG: 3 FG: 3 afi:5 msg: 1 ver -> 27
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t32561 [UPD]:4011: pfx: adv/wdn/sup/skp 1/0/0/1
default-bgp/spkr-tr2-common 0/RSP0/CPU0 t32558 [COMMON]:638: vrf default nbr fc00:bb00:3::1, set peer ack version to 27, afi 5, loc 2
default-bgp/spkr-tr2-gen 0/RSP0/CPU0 t32501 [GEN]:617: vrf default nbr 2000:0:0:1::1, old state 1, new state 3, fd type 2, fd 0

A mensagem decodificada BGP UPDATE mostra o tipo de atributo 40 e o TLV Tipo 5, que contêm o serviço SID fc00:bb00:1:e002::.

.

A mensagem completa decodificada de BGP UPDATE é a seguinte:

Message #1 - 126 bytes

FF FF FF FF  FF FF FF FF  FF FF FF FF  FF FF FF FF  
00 7E 02 00  00 00 67 90  0E 00 26 00  02 01 10 FC  
00 BB 00 00  01 00 00 00  00 00 00 00  00 00 01 00  
80 FC 00 AA  00 00 01 00  00 00 00 00  00 00 00 00  
01 40 01 01  00 40 02 00  80 04 04 00  00 00 00 40  
05 04 00 00  00 64 C0 28  25 05 00 22  00 01 00 1E  
00 FC 00 BB  00 00 01 E0  02 00 00 00  00 00 00 00  
00 00 00 3E  00 01 00 06  20 10 10 00  00 00 



BGP Marker:	0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
BGP Length:	0x007E	- 126 bytes
BGP Type:	0x02	- UPDATE

UPDATE
UNFEASIBLE ROUTES LENGTH:	0x0000	- 0 bytes
TOTAL PATH ATTRIBUTES LENGTH:	0x0067	- 103 bytes

Attribute

ATTRIBUTE FLAG:		0x90
ATTRIBUTE FLAG binary:	10010000
	Bit 0, the Optional bit, is 1 so this is an optional attribute
	Bit 1, the Transitive bit, is 0 so this is a non-transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 1 so the length field is 2 bytes
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x0E	- 14 
ATTRIBUTE LENGTH:	0x0026	- 38 bytes
ATTRIBUTE CONTENT:	0x00020110FC00BB000001000000000000000000010080FC00AA00000100000000000000000001

	AFI:		2 (0x0002)
	Sub AFI:	1 (0x01)
	NEXTHOP Length:	16 (0x10) bytes
	NEXTHOP:	FC00:BB00:0001:0000:0000:0000:0000:0001
	Numb of SNPAs:	0 (0x00)


	NLRI Length:	 128 bits	(0x80)
	MP_REACH_NLRI:	 FC00:AA00:0001:0000:0000:0000:0000:0001/128	(0xFC00AA00000100000000000000000001)




Attribute

ATTRIBUTE FLAG:		0x40
ATTRIBUTE FLAG binary:	01000000
	Bit 0, the Optional bit, is 0 so this is a well-known attribute
	Bit 1, the Transitive bit, is 1 so this is a transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 0 so the length field is 1 byte
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x01	- 1 
ATTRIBUTE LENGTH:	0x01	- 1 bytes
ATTRIBUTE CONTENT:	0x00	- IGP




Attribute

ATTRIBUTE FLAG:		0x40
ATTRIBUTE FLAG binary:	01000000
	Bit 0, the Optional bit, is 0 so this is a well-known attribute
	Bit 1, the Transitive bit, is 1 so this is a transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 0 so the length field is 1 byte
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x02	- 2 
ATTRIBUTE LENGTH:	0x00	- 0 bytes





Attribute

ATTRIBUTE FLAG:		0x80
ATTRIBUTE FLAG binary:	10000000
	Bit 0, the Optional bit, is 1 so this is an optional attribute
	Bit 1, the Transitive bit, is 0 so this is a non-transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 0 so the length field is 1 byte
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x04	- 4 
ATTRIBUTE LENGTH:	0x04	- 4 bytes
ATTRIBUTE CONTENT:	0x00000000	- 0




Attribute

ATTRIBUTE FLAG:		0x40
ATTRIBUTE FLAG binary:	01000000
	Bit 0, the Optional bit, is 0 so this is a well-known attribute
	Bit 1, the Transitive bit, is 1 so this is a transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 0 so the length field is 1 byte
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x05	- 5 
ATTRIBUTE LENGTH:	0x04	- 4 bytes
ATTRIBUTE CONTENT:	0x00000064	- 100




Attribute

ATTRIBUTE FLAG:		0xC0
ATTRIBUTE FLAG binary:	11000000
	Bit 0, the Optional bit, is 1 so this is an optional attribute
	Bit 1, the Transitive bit, is 1 so this is a transitive attribute
	Bit 2, the Partial bit, is not set
	Bit 3, the Extended Length Bit, is 0 so the length field is 1 byte
	The lower-order four bits of the Attribute Flag are unused and are set to 0000

ATTRIBUTE TYPE:		0x28	- 40 
ATTRIBUTE LENGTH:	0x25	- 37 bytes
ATTRIBUTE CONTENT:	0x0500220001001E00FC00BB000001E002000000000000000000003E00010006201010000000

	BGP Prefix-SID:
	Type:		 5 (0x05) - SRv6 L3 Service
	Length:		 34 - 0x0022
	Value:		 0x0001001E00FC00BB000001E002000000000000000000003E00010006201010000000
	Reserved:	 0x00
	Sub Type:	 1 (0x01)
	Sub Length:	 30 (0x001E)
	SRv6 SID = FC00:BB00:0001:E002:0000:0000:0000:0000
	SID Flags:	 0 (0x00)
	Endpoint Behavior:	 62 (0x003E)
	Reserved2 :	 0 (0x00)
	SRv6 SID Optional Type:	 1 (0x01)
	SRv6 SID Optional Len:	 6 (0x0006)
	SRv6 SID Optional Value:	 35253360001024 (0x201010000000)



NLRI
NLRI LENGTH:	UPDATE Length - 23 - TOTAL PATH ATTRIBUTES LENGTH - UNFEASIBLE ROUTES LENGTH
NLRI LENGTH:	126 - 23 - 103 - 0
NLRI LENGTH:	0 bytes

3. R3 Recebe a Atualização de BGP e a Instala na Tabela de Unicast BGP IPv6

O roteador R3 recebe uma atualização de BGP de R1, que pode ser observada habilitando-se a depuração de BGP em R3. O pacote de atualização de BGP recebido deve corresponder ao enviado por R1, como mostrado na saída da depuração.

bgp[1100]: [default-rtr]: UPDATE from fc00:bb00:1::1 contains nh fc00:bb00:1::1/128, gw_afi 5, flags 0x0, nlri_afi 5
bgp[1100]: [default-rtr]: NH-Validate-Create: addr=fc00:bb00:1::1/128, len=16, nlriafi=5, nbr=fc00:bb00:1::1, gwafi=5, gwlen=32, gwaddrlen=128::: nhout=0x0x7fc41b5fdcb0, validity=1, attrwdrflags=0x00000000
bgp[1100]: [default-rtr]: --bgp4_rcv_attributes--: END: nbr=fc00:bb00:1::1:: msg=0x0x7fc420108bdc/126, updlen=107, attrbl=0x0x7fc420108bf3/103, ipv4reachlen=0, msginpath=0x0x7fc3e2d54830, asloopcheck=1, attrwdrfl=0x00000000:: samecluster=0, local_as_prepended=0, attr_wdr_flags 0x00000000, myascount=0:: myconfedascount=0::rcvdata=0x0x7fc420108c5a/0, errptr=0x0x7fc420108c32/40
bgp[1100]: [default-rtr]: Comm-lib: Assigned ID (0x1d0000ac) for elem-type PREFIX_SID SRV6_L3SVC 
bgp[1100]: [default-rtr]: Comm-lib: Assigned ID (0x90000de) for elem-type Attribute 
bgp[1100]: [default-rtr] (ip6u): Received UPDATE from fc00:bb00:1::1 with attributes: 
bgp[1100]: [default-rtr] (ip6u): nexthop fc00:bb00:1::1/128, origin i, localpref 100, metric 0
bgp[1100]: [default-rtr] (ip6u): Received prefix fc00:aa00:1::1/128 (path ID: none) from fc00:bb00:1::1
bgp[1100]: [default-rtr] (ip6u): Handling OCRIB attrs while relacing path 0x7fc3e1be61d8. Old oc attr (nil), new oc attr (nil)
bgp[1100]: [default-rtr]: bgp_bmp_table_path_update_cb: Operation: 0x1, Inbound Post-Policy Route Mon is not enabled (0) (or) not primary active - return
bgp[1100]: [default-rtr] (ip6u): Done modify path (old tlv size=0 new tlv size=0) for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000000: usedpath=0x0x7fc3e1be61d8(fc00:bb00:1::1/128,fc00:bb00:1::1,0,0x2000000000060005), rcvdpath=0x0x7fc3e2d52b20: needmove=0, pcount=1 IdenticalPath=0, TLVPresent=0
bgp[1100]: [default-rtr]: bgp_set_path_metric:8712 afi 5 net fc00:aa00:1::1/128 path 0x7fc3e1be61d8 nh fc00:bb00:1::1/128 (0x7fc41b5fdcb0) metric 21
bgp[1100]: [default-rtr] (ip6u): bestpath: (full bp 1) start for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000200: lastpath=0x0x7fc3e1be61d8(fc00:bb00:1::1/128,fc00:bb00:1::1,0,0x2000000000060005): PELEM=0x0x7fc3e1a82930(lpathid=1, ver=2000371, fl=0x00000801, path=0x0x7fc3e1be61d8)
bgp[1100]: [default-rtr] (ip6u): bestpath: (full 1) calculated for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000200, pelemver=2000371, pelemfl=0x00000881: oldbest=0x0x7fc3e1be61d8(fc00:bb00:1::1/128,fc00:bb00:1::1,0,0x2000000001060005), newbest=0x0x7fc3e1be61d8(fc00:bb00:1::1/128,fc00:bb00:1::1,0,0x2000000001060005), lastpath=0x0x7fc3e1be61d8(fc00:bb00:1::1/128,fc00:bb00:1::1,0,0x2000000001060005), bumpv=1
bgp[1100]: [default-rtr] (ip6u): bestpath: change for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000200: oldbest=0x0x7fc3e1be61d8: PELEM=0x0x7fc3e1a82930(lpathid=1, ver=2000371, fl=0x00000901, path=0x0x7fc3e1be61d8)
bgp[1100]: [default-rtr] (ip6u): bestpath: update flags for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000200: oldtblattr=0x0x7fc41b5eccc0, oldnh=0x0x7fc41b5fdcb0: PELEM=0x0x7fc3e1a82930(lpathid=1, ver=2000371, fl=0x00000901, path=0x0x7fc3e1be61d8)
bgp[1100]: [default-rtr] (ip6u): bestpath: modified path: net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00003001+0x20000200: PELEM=0x0x7fc3e1a82930(lpathid=1, ver=2000371, fl=0x00001901, path=0x0x7fc3e1be61d8)
bgp[1100]: [default-rtr] (ip6u): bgp_srv6_get_alloc_mode_locator_from_policy: Use default SRv6 alloc mode as policy NOT in use/configured for net  and table TBL:default (2/1)
bgp[1100]: [default-rtr] (ip6u): bestpath: complete for net=fc00:aa00:1::1/128, nver=2000371, nfl=0x00007001+0x20000200: pselect=0x0, bumpv=1(1:1,0,0,0)
bgp[1100]: [default-rtr]: Received UPDATE from fc00:bb00:1::1 (length incl. header = 126)
bgp[1100]: [default-rtr]: Receive message dump for fc00:bb00:1::1:
bgp[1100]: [default-rtr]: ffff ffff ffff ffff ffff ffff ffff ffff 
bgp[1100]: [default-rtr]: 007e 0200 0000 6790 0e00 2600 0201 10fc 
bgp[1100]: [default-rtr]: 00bb 0000 0100 0000 0000 0000 0000 0100 
bgp[1100]: [default-rtr]: 80fc 00aa 0000 0100 0000 0000 0000 0000 
bgp[1100]: [default-rtr]: 0140 0101 0040 0200 8004 0400 0000 0040 
bgp[1100]: [default-rtr]: 0504 0000 0064 c028 2505 0022 0001 001e 
bgp[1100]: [default-rtr]: 00fc 00bb 0000 01e0 0200 0000 0000 0000 
bgp[1100]: [default-rtr]: 0000 003e 0001 0006 2010 1000 0000  
bgp[1100]: [default-rtr]: Enabling read from: fc00:bb00:1::1 readset: 1 msgcount: 0
bgp[1100]: [default-iowt]: bgp write for afi 4 for neighbor fc00:bb00:1::1 (fd 516)
bgp[1100]: [default-iowt]: bgp write for afi 5 for neighbor fc00:bb00:1::1 (fd 516)
bgp[1100]: [default-impt] (ip6u): START import walk from 2000371 to 2000372 skip_walk 1
bgp[1100]: [default-rib2] (ip6u): RIB thread triggered for versioned walk: current version 2000371, acked version 2000371, target version 2000371
bgp[1100]: [default-rib2] (ip6u): RNH rib opaque update for (IPv6 Unicast)
bgp[1100]: [default-rib2] (ip6u): RIB thread triggered for RNH walk for nh table(IPv6 Unicast): current version 2000371, target version 2000372
bgp[1100]: [default-lbl] (ip6u): Label update triggered: current version 2000371, target version 2000372, mpls component is up  
bgp[1100]: [default-lbl]: Table: TBL:default (2/1) bgp_label_srv6_sid_config_release: label_sid_need_eval:0 loc trigger:0 srv6 enabled:1 label disabled:1 dual mode:0 label alloc mode:2 sid alloc mode:0 sid release:0
bgp[1100]: [default-lbl]: uSID WLIB allocation is (LIB Default)
bgp[1100]: [default-lbl]: Table: TBL:default (2/1) bgp_label_thread_walk_type: rd:0x7fc3e1efbf30(ALLzero:0:0) rd_flags:0x1 SRv6 eval/en/cnt:1/1/1 locator:MAIN Label up/dis/cnt: 1/1/0 dual mode:0 ibgp_nhself_count:0 policy_set_nhself:0
bgp[1100]: [default-lbl] (ip6u): rd:0x7fc3e1efbf30 sid_walk:1 label_walk:0
bgp[1100]: [default-lbl]: uSID WLIB allocation is (LIB Default)
bgp[1100]: [default-upd] (vpn4u): Started updgrp timer for updgrp 0.1:: delay=0.010, delaytype=0
bgp[1100]: [default-lbl] (ip6u): SRv6 SID process for net: TBL:default (2/1)fc00:aa00:1::1/128(SID N) extflags 20000000 Default locator Y UP/exh/oor/rclm MAIN/N/N/N mode 0 clear handle 0
bgp[1100]: [default-lbl] (ip6u): SRv6 SID process for net: TBL:default (2/1)fc00:aa00:1::1/128 point 1 sid_mode 0 clear_handle 0
bgp[1100]: [default-lbl]: uSID WLIB allocation is (LIB Default)
bgp[1100]: [default-lbl] (ip6u): Label update run from 2000371 target label version 2000372, rib version 2000371, bgp table version 2000372,best-external allocs 0
bgp[1100]: [default-lbl] (ip6u): Wake up rib thread, label version 2000372, rib version 2000371, bgp table version 2000372,
bgp[1100]: [default-rib2] (ip6u): RIB thread triggered for versioned walk: current version 2000371, acked version 2000371, target version 2000372
bgp[1100]: [default-rib2] (ip6u): RNH rib opaque update for (IPv6 Unicast)
bgp[1100]: [default-rib2] (ip6u): RIB thread triggered for RNH walk for nh table(IPv6 Unicast): current version 2000371, target version 2000372
bgp[1100]: [default-rib2] (ip6u): Rib Batch-buf Route ADD: table=TBL:default (2/1), tableid=0xe0800000, net=fc00:aa00:1::1/128, netfl=0x00003001: label=1048577, dist=200, attrkey=0x00000000, pathcount=1: batchres=1, succ=1, send=0 locator prefix No, 0
bgp[1100]: [default-rib2] (ip6u): Revise route batch: installing fc00:aa00:1::1/128 with next hop fc00:bb00:1::1(tbl-id=0xe0800000, ifh=0x0), pathribflags: 0x9800000008, #ext-comms=0, to IP-RIB table[0xe0800000]
bgp[1100]: [default-rib2] (ip6u): [0]: Rib Batch-buf Path ADD: table=TBL:default (2/1), net=fc00:aa00:1::1/128: nh=fc00:bb00:1::1, nhifh=0x00000000, nhtableid=0xe0800000: rlabel=1048577, metric=0, bsid=0, numecomms=0: pelemfl=0x00001001, pathfl=0x2000000001060005,pathribfl=0x9800000008, nhresplenmin=0 (constraint=1):: batchres=1, succ=1, sendbatch=0
bgp[1100]: [default-rib2] (ip6u): Sending convergence info for IPv6 Unicast - not converged, version: 0, last received version 0
bgp[1100]: [default-upd] (ip6u): Started updgrp timer for updgrp 0.1:: delay=0.010, delaytype=0
bgp[1100]: [default-rib2] (ip6u): vrf default: RIB update run to 2000372: installed 0, modified 1, skipped 0, removed 0 IPv6 Unicast prefixes, installed 0 attributes, removed 0 attributes.
bgp[1100]: [default-rib2] (ip6u): RIB thread finished versioned walk: table version 2000372, acked table version 2000372
bgp[1100]: [default-upd] (vpn4u): Starting updgen walk for updgrp 0.1:: targetver=463:  tblver=463, labelver=463, minfwdver=463, ackdfwdver=463, standbyver=0
bgp[1100]: [default-upd] (ip6u): Starting updgen walk for updgrp 0.1:: targetver=2000372:  tblver=2000372, labelver=2000372, minfwdver=2000372, ackdfwdver=2000372, standbyver=0
bgp[1100]: [default-upd] (ip6u): Computing updates for update sub-group 0.1 (Regular)
bgp[1100]: [default-upd] (ip6u): bgp_srv6_execute_sid_alloc_mode_policy: Use default SRv6 alloc mode per-vrf as policy NOT in use/configured for net  and table TBL:default (2/1)
bgp[1100]: [default-upd]: table-attr walk for table TBL:default (2/1), resume version 0, subgrp version 2000371, target version 2000372
bgp[1100]: [default-upd] (ip6u): process UPDATE for: tbl=TBL:default (2/1), afi=5: ug=0.1, (Regular), pelem (Regular), sg=0.1, ugfl=0x00104183: bgpctxfl=0x00, tblctxfl=0x10000021, ltblctxfl=0x10000021, sendlab=0: net=fc00:aa00:1::1/128, nver=2000372: PELEM=0x7fc3e1a82930 (lpathid=1, ver=2000372, fl=0x00001001): PATH=0x7fc3e1be61d8 (fc00:bb00:1::1/128,fc00:bb00:1::1,0, 0x2000000001060005)::: allowbe=0, isbe=0, allowspurwdr=0, pelem-send=1, pelem-wdr=0, netExtflag=20000000
bgp[1100]: [default-upd] (ip6u): No unreachable (not advertising to sender: fc00:bb00:1::1) sent to sub-group 0.1 (Regular) with fc00:aa00:1::1/128 - already withdrawn

O roteador R3 gera um rastreamento BGP correspondente ao processamento de atualização de R1, o que resulta na atualização da tabela unicast IPv6 do BGP em R3. Essa atualização, que contém o atributo BGP tipo 40, envolve a instalação dos SIDs recebidos junto com os prefixos unicast BGP IPv6 associados de R1.

RP/0/RSP0/CPU0:R3#show bgp trace
default-bgp/spkr-tr2-imp 0/RSP0/CPU0 t16100 [IMPORT]:6661: Skipping Import walk: import ver 2000371 -> 2000372: afi 5 forced 0
default-bgp/spkr-tr2-rib 0/RSP0/CPU0 t30391 [RIB]:17177: RIB walk for afi IPv6 Unicast: target version 2000371, min_fwdtable_version 2000371, import_version 2000372,  label_version 2000371, table_version 2000372
default-bgp/spkr-tr2-label 0/RSP0/CPU0 t16061 [LABEL]:8505: label walk afi:IPv6 Unicast, lbl ver 2000371 -> 2000372, be 0, skp 0  upd 0
default-bgp/spkr-tr2-label 0/RSP0/CPU0 t16061 [LABEL]:8510: label walk afi:IPv6 Unicast, lbl ver 2000371 -> 2000372, be 0, skp 0  upd 1
default-bgp/spkr-tr2-rib 0/RSP0/CPU0 t30391 [RIB]:17177: RIB walk for afi IPv6 Unicast: target version 2000372, min_fwdtable_version 2000371, import_version 2000372,  label_version 2000372, table_version 2000372
default-bgp/spkr-tr2-rib 0/RSP0/CPU0 t30391 [RIB]:14681: send converge to RIB, afi IPv6 Unicast, tableid 0xe0800000, converged 0, send_version 0, last_recv_version 0
default-bgp/spkr-tr2-rib 0/RSP0/CPU0 t30391 [RIB]:15892: RIB(default:v6u): ver 2000371 -> 2000372 :pfx inst/upd/skip/rem 0/1/0/0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t16101 [UPD]:11342: Updgen - TBL:default (2/1) UG: 0.1 SG: 0.1 msg: 0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t16101 [UPD]:11344: Updgen - pfx: [tot]  adv/wdn/sup/skp/be[1] 0/0/0/1/0
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t16101 [UPD]:11351: Updgen - fpx: wdn/skp[0/0] ver: 2000371 -> 2000372 res ver: 0 -> 2000372
default-bgp/spkr-tr2-common 0/RSP0/CPU0 t16101 [COMMON]:3628: vrf default nbr fc00:bb00:1::1, set peer ack version to 2000372, afi 5, loc 4
default-bgp/spkr-tr2-upd 0/RSP0/CPU0 t16101 [UPD]:11663: Updgen - Skip EoR for Tbl:(TBL:default (2/1)) subgrp:(1) UG:(1) end 2000372

RP/0/RSP0/CPU0:R3#show bgp ipv6 unicast received-sids 

BGP router identifier 10.0.0.3, local AS number 1
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 46
BGP table nexthop route policy: 
BGP main routing table version 46
BGP NSR Initial initsync version 6 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop                            Received Sid
*>ifc00:aa00:1::1/128 fc00:bb00:1::1                      fc00:bb00:1:e002::
*> fc00:aa00:3::3/128 ::                                  NO SRv6 Sid

Processed 2 prefixes, 2 paths

4. R3 instale o RIB e o FIB

Eventualmente, R3 instala o RIB e o FIB para concluir o processo de sinalização. Em seguida, R3 atua como Headend SRv6 com a lista SID fc00:bb00:1:e002::. Esse R1 de ingresso atua como Headend SRv6 com encapsulamento em uma política SR, abreviada como H.Encaps (RFC 8986, seção 5.1). Esse comportamento encapsula o pacote em um cabeçalho IPv6, impondo uma lista de segmentos e adicionando o SRH, se necessário. Neste caso, não há necessidade de adicionar o SRH, pois há apenas um segmento. O pacote será enviado com o endereço de destino fc00:bb00:1:e002::, que é o SID de serviço em R1 com o comportamento do ponto de extremidade SRv6 UDT6.

RP/0/RSP0/CPU0:R3#show route ipv6 fc00:aa00:1::1/128 detail 

Routing entry for fc00:aa00:1::1/128
  Known via "bgp 1", distance 200, metric 0, type internal
  Installed Jun  8 17:52:31.546 for 00:53:55
  Routing Descriptor Blocks
    fc00:bb00:1::1, from fc00:bb00:1::1
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      NHID: 0x0 (Ref: 0)
      Path Grouping ID: 1
      SRv6 Headend: H.Encaps.Red [f3216], SID-list {fc00:bb00:1:e002::}
  Route version is 0x1f (31)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_RECURSIVE (12) SVD Type RIB_SVD_TYPE_LOCAL
  Download Priority 4, Download Version 166
  No advertising protos. 

RP/0/RSP0/CPU0:R3#show cef ipv6 fc00:aa00:1::1/128
fc00:aa00:1::1/128, version 166, SRv6 Headend, internal 0x5000001 0x40 (ptr 0x7941f0f4) [1], 0x0 (0x0), 0x0 (0x7ad58368)
 Updated Jun  8 17:52:31.551
 Prefix Len 128, traffic index 0, precedence n/a, priority 4
  gateway array (0x78eac428) reference count 1, flags 0x2010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x78f4f4d8) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Jun  8 17:52:31.551
 LDI Update time Jun  8 17:52:31.551

  Level 1 - Load distribution: 0
  [0] via fc00:bb00:1::/128, recursive

 Accounting: Disabled
   via fc00:bb00:1::/128, 5 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x7941edb4 0x0]
    next hop fc00:bb00:1::/128 via fc00:bb00:1::/48
    SRv6 H.Encaps.Red SID-list {fc00:bb00:1:e002::}

    Load distribution: 0 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   TenGigE0/0/0/1            remote         

A figura 4 mostra o formato do pacote quando o roteador R3 (fc00:aa00:3::3) executa ping no R1 (fc00:aa00:1::1).

Figura 4. Processamento de pacotes ao longo do caminho de unicast IPv6 BGP sobre SRv6