[j-nsp] AS path preservation when importing from instance.inet.0 to inet.0

[Paul S.]

Hi guys,

So, in a bit of a peculiar situation. I think rather than explaining it, 
it's possibly easier to express through configs. I've added it at the 
end of the email.

Basically, my local-as in a ri is different compared to my local-as set 
in the master instance. When I import a BGP route (that I'm actually 
originating in the RI and would like to originate in the master instance 
too), and then export it to other peers -- the originating ASN gets 
rewritten to the master instance's ASN instead.

For example - AS-path in RI A for 20.20.20.0/24 is [2] I

When imported via instance-import to inet.0 and exported to other peers, 
I can see that the AS-path becomes [1] I. What I'd like it to be is [1 
2] I, i.e: the RI looks like a downstream adjacency of the master 
instance instead.

Is there any way to achieve this (other than setting up a lt tunnel and 
peering with the master)? Speaking of the lt tunnel, is there any clear 
drawbacks to using it? Once upon a time, I recall hearing that it was 
bandwidth constrained. I'm doing this on a Trio MX.

Pointers welcome, thank you for reading.

(As to why the multi-asn stupidity, that's due to a limitation on our 
upstream provider's side. Sadly, no control over that)


Config from the "*master*" instance:


routing-options {

     router-id 1.1.1.1;

    autonomous-system 1;

}

protocols

{

     bgp {

        nei 10.10.10.10 peer-as 500;

    }

}


Config from a *second* routing-instance

A {

     instance-type virtual-router;

     interface x;

     routing-options {

         router-id 2.2.2.2;

     }

     protocols { bgp {

         nei 10.10.10.15 peer-as 500;

         nei 10.10.10.15 local-as *2;*

      }

}