Where should I set the route distinguisher value on IOS-XR?

[steven.crutchley]

When I am setting the RD (route distinguisher) on IOS-XR, I have two options.

One is under the VRF itself:

vrf ACME
 rd 1:100
 address-family ipv4 unicast
  import route-target 1:100
  export route-target 1:100

Or I can set it under BGP and leave it off of the vrf definition:

router bgp 100
 vrf ACME
  rd 1:100
  address-family ipv4 unicast
  neighbor 1.2.3.4 
    remote-as 65123
      address-family ipv4 unicast
        route-policy ALLOW-ALL in
        route-policy ALLOW-ALL out
        as-override

As far as I know, the RD is only ever used in BGP to, as the name suggests, to differentiate/distinguish routes between VRF. If I configure VRF-lite an RD isn't needed.

But why would I not just always configure the RD under the VRF definition and leave it out of the BPG config? Or vice versa! I've never really understood the difference between the different places it can be configured.

[Harold Ritter · Accepted solution]

Hi @steven.crutchley ,

> Or vice versa! I've never really understood the difference            > between the different places it can be configured.

There is no difference in fact. It is just that originally, you could only configure the RD under the BGP configuration. They might have added it under it the VRF configuration to make it congruent to what it is under IOS and IOS-XE and didn't remove it from the BGP configuration for backward compatibility purposes. 

[shambhu.kumar]

Hello,

RD is not required in VRF-lite.

Either you configure RD under VRF or BGP the purpose is same. Earlier RD was configured under BGP but later it was introduced and feasible to configure under VRF as well.

Regards