Configuración de BGP Global IPv6 sobre SRv6

Introducción

Este documento describe el flujo del plano de control cuando se aplica la encapsulación Segment Routing over IPv6 (SRv6) a la sesión de unidifusión BGP IPv6.

Antecedentes

Consulte la Guía de Configuración de Segment Routing para Cisco ASR 9000 Series Routers, IOS XR Release 24.1.x, 24.2.x, 24.3.x, 24.4.x para obtener información adicional.

Topología

La topología utilizada en este documento se muestra en la Figura 1. El dominio SRv6 consta de tres routers, todos los cuales funcionan en Cisco IOS-XR. La infraestructura subyacente SRv6 se implementa usando IS-IS con uSID SRv6. El peering unicast BGP IPv6 se establece entre los routers R1 y R3, mientras que el router R2 no participa en BGP y funciona como un router P en esta configuración. La interfaz Loopback 6 en R1 y R3 representa un prefijo IPv6 que se debe intercambiar entre los dos peers unidifusión BGP IPv6.

Figura 1. Diagrama de topología de unidifusión BGP ipv6 sobre SRv6

Configuración SRv6

Esta sección muestra la configuración de los tres routers SRv6. El router R2 incluye solamente la configuración SRv6, ya que no participa en BGP.

Configuración del Router R1

El router R1 forma parte del dominio SRv6 con un localizador de fc00:bb00:1::/48. También funciona como un router unicast BGP IPv6, originando el prefijo local fc00:aa00:1::1/128. Además, establece el peering unicast BGP IPv6 con el router R3 sobre la infraestructura SRv6. La configuración resaltada en negrita sirve como punto de partida para depurar el flujo de control descrito en este documento y es el único desencadenador utilizado en todo el proceso.

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
   !

Configuración del Router R2

El router R2 es parte del dominio SRv6 con un localizador de fc00:bb00:2::/48. No participa en BGP y funciona como un router P dentro de esta topología.

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
   !

Configuración del Router R3

El router R3 es parte del dominio SRv6 con un localizador de fc00:bb00:3::/48. Tiene un peering unicast BGP IPv6 con el router R1, y ambos intercambian los prefijos IPv6 de sus 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
   !
  !
 !        
!

Flujo de señalización del SID SRv6

En la infraestructura SRv6 subyacente, cada router tiene información de estado de link en toda la topología, que cada uno anuncia su localizador SRv6 a través del protocolo ISIS de estado de link. La base de datos de ISIS en R1 muestra el localizador de todos los routers que participan en el dominio 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

Esta implementación de SRv6 admite la superposición de tráfico de tabla de enrutamiento global (GRT). Cuando se habilita el servicio de superposición de unidifusión IPv6 BGP global en R1 y R3, cada router genera un nuevo SID de servicio. Este SID de servicio está asociado con el VRF predeterminado y utiliza el comportamiento de punto final uDT6 en este escenario. Este SID de servicio se debe intercambiar entre los peers unicast IPv6 BGP para habilitar el reenvío SRv6 entre los dos peers BGP. La siguiente sección describe los pasos del flujo de señalización BGP, empezando desde la ejecución del disparador (habilitando encapsulation-type srv6) hasta el punto en que el reenvío SRv6 está programado en el Router R3.

1. Estado anterior a habilitar la encapsulación de SRv6

Antes de habilitar la encapsulación SRv6 en el SAFI de unidifusión IPv6 para el par BGP, el router R1 debe tener prefijos BGP IPv6 con SID de servicio asignados. Esto ocurre cuando 'segment-routing srv6' está habilitado en el SAFI global de unidifusión IPv6 en R1. La salida muestra el SID local fc00:bb00:1:e002:: se asigna a todos los prefijos en unidifusión 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 servicio es programado localmente por el proceso sid_mgr en R1, que tiene un comportamiento de punto final como uDT6, que está asociado con el vrf predeterminado y es propiedad de bgp. Esto simplemente significa cuando el paquete de recepción R1 con la dirección de destino coincide con el servicio SID fc00:bb00:1:e002:: y es el último segmento, el R1 debe desencapsular el encabezado y enviar el paquete desencapsulado a la búsqueda FIB de la tabla vrf predeterminada IPv6. Esto es según RFC8986, que enumera todo el comportamiento de los terminales SRv6. Observe la salida donde muestra el sid_mgr para crear el servicio SID fc00:bb00:1:e002:: y pasar esta información a RIB y finalmente 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

Dado que R1 no ha habilitado la encapsulación SRv6 bajo su par unicast BGP ipv6, R1 anuncia estos prefijos hacia R3 sin SRv6 TLV en la actualización BGP, aunque R1 haya asignado localmente SID locales.

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: 

El router R3 recibe la actualización del router R1 sin SID. R3 instala los prefijos recibidos de R1 en su tabla RIB y FIB sin un encabezado 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 encapsulación SRv6

La habilitación de la encapsulación SRv6 hace que R1 envíe un mensaje de actualización de BGP a su peer con el tipo de atributo 40, que se utiliza en Segment Routing para anunciar un prefijo BGP con un identificador de routing de segmento (SID) específico. El router R1 envía la ACTUALIZACIÓN a R3 para el prefijo IPv6 fc00:bb00:3::1 (Paso 1) con el SID asociado fc00:bb00:1:e002::. Al recibir la ACTUALIZACIÓN, el Router R3 actualiza su tabla unicast BGP IPv6 (Paso 2) y posteriormente actualiza sus tablas RIB y FIB (Paso 3). La figura 2 ilustra el flujo de señalización BGP junto con los pasos correspondientes.

Figura 2. Flujo de señalización BGP después de habilitar la encapsulación srv6

El resultado muestra el registro de depuración de BGP inmediatamente después de habilitar la encapsulación SRv6 en el par R3, lo que muestra que R1 envía un mensaje de actualización de BGP a 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

El resultado muestra la entrada de seguimiento BGP en 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

El mensaje BGP UPDATE descodificado muestra el tipo de atributo 40 y el Tipo TLV 5, que contienen el SID de servicio fc00:bb00:1:e002::.

.

El mensaje BGP UPDATE descodificado completo es el siguiente:

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 recibe la actualización BGP y la instala en la tabla de unidifusión IPv6 BGP

El router R3 recibe una actualización de BGP de R1, que se puede observar habilitando la depuración de BGP en R3. El paquete de actualización de BGP recibido debe coincidir con el enviado por R1, como se muestra en la salida de depuración.

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

El router R3 genera un seguimiento BGP correspondiente al procesamiento de actualización de R1, lo que finalmente resulta en la actualización de R3 de su tabla unicast IPv6 BGP. Esta actualización, que contiene el atributo BGP tipo 40, implica la instalación de los SID recibidos junto con los prefijos unicast IPv6 BGP asociados 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 instalar el RIB y FIB

Finalmente, R3 instala el RIB y el FIB para completar el proceso de señalización. R3 actuará como cabecera SRv6 con la lista de SID fc00:bb00:1:e002::. Esta entrada R1 actúa como cabecera SRv6 con encapsulación en una política SR, abreviada como H.Encaps (RFC 8986, sección 5.1). Este comportamiento encapsula el paquete en un encabezado IPv6, impone una lista de segmentos y agrega SRH si es necesario. En este caso, no es necesario agregar SRH ya que solo hay un segmento. El paquete se enviará con la dirección de destino fc00:bb00:1:e002::, que es el SID de servicio en R1 con comportamiento SRv6 Endpoint 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         

La figura 4 muestra el formato del paquete cuando el router R3 (fc00:aa00:3::3) hace ping a R1 (fc00:aa00:1::1).

Figura 4. Procesamiento de paquetes a lo largo de la ruta de unidifusión BGP IPv6 sobre SRv6