BGP Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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BGP labeled unicast version 6

Updated: February 28, 2026

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Overview

Details requirements, unsupported features, and configuration procedures for implementing BGP labeled unicast version 6 in MPLS networks, enabling IPv6 transport and label assignment functions.

BGP labeled unicast version 6 is a routing feature that

  • enable MPLS transport between Provider Edge (PE) routers separated by multiple IGP boundaries (intra-AS) or autonomous systems (inter-AS)

  • use autonomous system border routers (ASBRs) to advertise PE loopback prefixes and their MPLS label bindings, and

  • support iBGP between area border routers (ABRs) and eBGP between ASBRs for route exchange.

Key considerations for BGP LU and VPN services across autonomous systems

Multihop eBGP can be used between PEs in different autonomous systems to exchange VPN routes. Services such as 6PE operate between PEs that have BGP Labeled Unicast connectivity.

BGP LU feature reduces scale requirements for IGP labeled prefixes and adjacencies. To prevent potential scaling issues when BGP Labeled Unicasts are not configured, you must configure the hw-module command before enabling BGP LU and restart the router for the changes to take effect.

BGP LU v6 extends this functionality to IPv6 networks, allowing you to apply the same MPLS transport principles over IPv6.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description
BGP Labeled Unicast Version 6 Release 7.3.16

This feature extends the BGP Labeled Unicast (LU) functionality over IPv6. This feature provides connectivity between PEs to run services, such as L3VPN and 6PVE. This feature allows the PEs to transport traffic across autonomous systems (AS) boundaries.

BGP LU allows you to transport MPLS traffic across IGP boundaries. By advertising loopbacks and label bindings across IGP boundaries routers communicate with other routers in remote areas that do not share the same local IGP.

Limitations for BGP labeled unicast version 6

You must understand the limitations of BGP Labeled Unicast Version 6 (BGP LU v6) to ensure proper deployment and avoid unsupported configurations that may cause network issues.

  • 6VPE over BGP LU is not supported

  • Inter-Address Family Identifier (AFI) is not supported.

  • BGP PIC core feature is not supported.

  • Coexistence of 6PE with the same neighbor is not supported.

  • Coexistence of BGP LU v6 IPv6 unicast address family is not supported.

  • VPNv6 over BGP LU v6 and Inter-AS Option-C with BGP LU v6 are not supported.

  • Link-local addresses are not supported.

  • Cases where BGP LU itself is the transport are not supported.

  • Carrier Supporting Carrier version 6 is not supported.

Configure BGP labeled unicast version 6

Enable and configure BGP LU v6 on the hardware module, set up the BGP router and router ID, configure IPv6 unicast address family with route redistribution and label allocation, establish BGP neighbor and session parameters, and apply route policies for IPv6 labeled-unicast.

Use this task to enable labeled IPv6 routing with BGP LU v6, ensuring proper neighbor configuration and route policy application for efficient labeled-unicast forwarding.

Before you begin

Verify hardware module supports BGP LU and that you have the necessary router and neighbor information.

Follow these steps to enable and configure BGP LU v6:

Procedure

1.

Enable BGP labeled unicast on the hardware module

Example:

Router(config)# hw-module profile cef bgplu enable
2.

Configure the BGP router and router ID:

Example:

Router(config)# router bgp 1
Router(config-bgp)# bgp router-id 2001:DB8::1
3.

Configure the IPv6 unicast address family and redistribute connected routes with label allocation:

Example:

Router(config-bgp)# address-family ipv6 unicast
Router(config-bgp-af)# redistribute connected route-policy set-lbl-idx
Router(config-bgp-af)# allocate-label all
Router(config-bgp-af)# exit
4.

Configure the BGP neighbor and session parameters:

Example:

Router(config-bgp)# neighbor 2001:DB8::2
Router(config-bgp)# remote-as 1
Router(config-bgp)# update-source Loopback 0
5.

Configure the IPv6 labeled-unicast address family and apply route policies:

Example:

Router(config-bgp)# address-family ipv6 labeled-unicast
Router(config-bgp)# route-policy pass-all in
Router(config-bgp)# route-policy pass-all out
Router(config-bgp)# commit
6.

Verify the configuration:

Example:

Router# show running-config
hw-module profile cef bgplu enable
router bgp 1
 bgp router-id 2001:DB8::1
 address-family ipv6 unicast
  redistribute connected route-policy set-lbl-idx
  allocate-label all
  exit
 neighbor 2001:DB8::2
 remote-as 1
 update-source Loopback 0
  address-family ipv6 labeled-unicast
   route-policy pass-all in
   route-policy pass-all out
7.

Use the show hw-module profile cef to verify that the BGP LU has been configured.

Example:

Router# show hw-module profile cef
Thu Jun 17 00:06:32.974 UTC
------------------------------------------------------------------------------------ 
Knob                        Status        Applied   Action         
------------------------------------------------------------------------------------
BGPLU                      Configured      Yes       None    
LPTS ACL                   Unconfigured    Yes       None           
Dark Bandwidth             Unconfigured    Yes       None           
MPLS Per Path Stats        Unconfigured    Yes       None           
Tunnel TTL Decrement       Unconfigured    Yes       None           
High-Scale No-LDP-Over-TE  Unconfigured    Yes       None           
IPv6 Hop-limit Punt        Unconfigured    Yes       None           
IP Redirect Punt           Unconfigured    Yes       None
8.

Use the show cef ipv6 command to verify the details of route paths along with the BGP and transport label information.

Example:

Router# show cef ipv6 192:168:9::80/128

Wed Jun 16 07:42:04.789 UTC
192:168:9::80/128, version 27, internal 0x5000001 0x40 (ptr 0x93f2d478) [1], 0x0 (0x93ef6cc0), 0xa08 (0x9460a8a8)
 Updated Jun 16 07:36:00.189
 Prefix Len 128, traffic index 0, precedence n/a, priority 4, encap-id 0x1001000000001
   via 10:0:1::51/128, 3 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x94720660 0x0]
    recursion-via-/128
    next hop 10:0:1::51/128 via 16061/0/21
     next hop fe80::7af8:c2ff:fee4:20c0/128 Hu0/0/0/27   labels imposed {16061 25001}
/*
16061 - Transport Label
25001 – BGP Label 
*/
9.

Use the show bgp ipv6 unicast labels to verify the BGP LU version 6 routes and BGP label information in BGP process.

Example:

Router# show bgp ipv6 unicast labels
Wed Jun 16 07:34:58.968 UTC
BGP router identifier 10.0.1.50, local AS number 1
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 6
BGP main routing table version 6
BGP NSR Initial initsync version 3 (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        Rcvd Label      Local Label
*> 192:168::/64        192:168:1::70   nolabel         24006
*>i192:168:9::80/128   10:0:1::51      25001           nolabel

Processed 2 prefixes, 2 paths

BGP LU v6 is enabled and configured, allowing labeled IPv6 routing with proper neighbor and route policy settings.

What to do next

Reload the router for the hw-module profile cef bgplu enable command to take effect.