IOS XR MPLS L3 vpn - is VPNv4 address family activated by default?

[rocko2006]

Hi guys,

I wondering if VPNv4 address family activated by default in IOS XR.

For example in IOS you use:

address-family vpnv4
  neighbor x.x.x.x activate
....

but in IOS XR  you use:

neighbor 66.119.95.41
   address-family vpnv4 unicast

....

And i dont seem to find any documentation that states if the address family  needs a command to activate just like IOS or if it is activated by default.

Also i dont have access to IOS XR equipment to test the configuration.

Any help would be appreciated.

Regards,

[xthuijs · Accepted solution]

ah good question, so in XR you dont need to use the neighbor <SAFI> activate, you will need to enable the vpvn4 address family in the globla bgp config and then on a per neighbor bases, like this:

RP/0/RSP0/CPU0:A9K-BNG#sh run router bgp
Sat Nov  8 08:49:44.377 EDT
router bgp 64524
 nsr
 bgp router-id 10.86.188.99
 ibgp policy out enforce-modifications
 address-family ipv4 unicast
  redistribute subscriber metric 123
 !
 address-family vpnv4 unicast
 !enables vpnv4 for BGP and start the sw subsystem
!
 neighbor 123.1.1.2
  remote-as 300
  ebgp-multihop 5
  dmz-link-bandwidth
  update-source Loopback123
  address-family ipv4 unicast
   multipath
   route-policy pass-all in
   route-policy pass-all out
  !
  address-family vpnv4 unicast
  ! neighbor activation to send this SAFI in the BGP OPEN message
 !

regards

xander

[rocko2006]

Thanks for clearing that out Xander.

It really make sense. I also have tested it in a production environment and works well :D

Cheers,

JP

[adrian.taranu]

Hi Alexander,

You are mentioning:

1. " address-family vpnv4 unicast
 !enables vpnv4 for BGP and start the sw subsystem"

Can you please tell what is "sw subsystem" ? and where can i read more about it ? I have extensively searched all Cisco Press books, CCO and TKL, and Internet and found only some docs which are referring to it very vague but with no explanation.

2. I find a strange way of doing different things with the same command.

--Under router bgp "address-family vpnv4 unicast
 !enables vpnv4 for BGP and start the sw subsystem".  

--and under neighbor it does a different thing:

"address-family vpnv4 unicast
  ! neighbor activation to send this SAFI in the BGP OPEN message".

--

Why is not enough to give the router this command once (say under router bgp) and do both things ? Why bgp neighbors are not activated by default  so we need same command (but under neigbor ) to activate an send the SAFI ?

--

Thank you very much.

Best regards,

Adrian

Can you please give a more insight regarding this ?

[xthuijs]

hi adrian,

the router bgp addr family is a "global" configuration pertaining to all neighbors that want to use tht addr family.

for instance best external, route target retention and all that can be configured here. it also helps the sw to enable the structures and tables necessary to run vpnv4.

the neighbor command is specific to the neighbor: not every neighbor maybe wants to run all addr families for whatever purpose that is and there is different configuration there that applies on a per neighbor bases.

so there is good reason to have 2 separate sections there say system or bgp process wide and then on a per neighbor bases.

if you like to read more on mp-bgp, I think the "internet routing architectures" is a very nice one to dig into.

cheers

xander

[adrian.taranu]

Thank you very much!