BGP - Support for iBGP Local-AS on IOS-XR

[Thomas Hofegger]

Is there a support for iBGP Local-AS on IOS-XR like there is for  IOS-XE (https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-3s/irg-xe-3s-book/irg-local-as-policy.pdf) and (https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/15-s/irg-15-s-book/irg-ibgp-localAS-dualAS.pdf) for Dual-AS? This would be a great help for merging two ASes.

[tkarnani]

Hello Thomas

i have not tested this feature, but i see this feature was added in 6.0 and above code

CSCus86766    IOS-XR iBGP local-as dual-as feature request

local-as 3 no-prepend replace-as dual-as

What code are you running?

[Thomas Hofegger]

Hi tkarnani,

I tried it out on VIRL with IOS-XR 6.1.3  in using the configuration suggested for IOS-XE as I coudn't find anything on XR. Unfortunately I don't have access to CSCus86766. I would appreciate if you have an configuration example

RP/0/0/CPU0:XR1(config)#sh configuration
Wed Sep  5 13:11:03.167 UTC
Building configuration...
!! IOS XR Configuration 6.1.2
router bgp 100
 neighbor 1.1.1.12
  remote-as 8412
  local-as 8412 no-prepend replace-as dual-as
  address-family ipv4 unicast
   route-reflector-client

RP/0/0/CPU0:XR1(config)#commit
Wed Sep  5 13:11:09.986 UTC

% Failed to commit one or more configuration items during a pseudo-atomic operation. All changes made have been reverted. Please issue 'show configuration failed [inheritance]' from this session to view the errors

RP/0/0/CPU0:XR1(config)#show configuration failed      
Wed Sep  5 13:11:38.395 UTC
!! SEMANTIC ERRORS: This configuration was rejected by
!! the system due to semantic errors. The individual
!! errors with each failed configuration command can be
!! found below.


router bgp 100
 neighbor 1.1.1.12
  remote-as 8412
!!% Change would result in external neighbor (1.1.1.12) with internal-only config
 !
!
end

tia

thomas

[tkarnani · Accepted solution]

I tried to configure on an asr9k running 6.3.2, i dont have a peer setup at this time. but it took the configuration are you modifying an existing session?

RP/0/RSP0/CPU0:ASR9006-M#show configuration commit changes last 1
Wed Sep  5 05:03:28.493 EDT
Building configuration...
!! IOS XR Configuration 6.3.2
router bgp 1234
 address-family ipv4 unicast
 !
 neighbor 1.1.1.12
  remote-as 8412
  local-as 8412 no-prepend replace-as dual-as
  address-family ipv4 unicast
   route-reflector-client
  !
 !
!
end

RP/0/RSP0/CPU0:ASR9006-M#

[Thomas Hofegger]

Hi tkarnani,

I tried it out  on  6.3.3 XRv and everything looks good! It's configurable and a BGP session with preserved iBGP attributes could be established.

many thanks

Thomas