[j-nsp] l3vpn

[Alexander Arsenyev (GU/ETL)]

OK, I'll try re-phrase the originator's question in the following way (applicable to JUNOS because this is "juniper-nsp" mailing list):

"Can we configure same interface under more than one routing-instances similar to the below example:
[edit routing-instances]
aggr {
      instance-type vrf;
	vrf-import reject-all;
	vrf-export aggr-export;
	interface foo;			/* switch interface */
	routing-options auto-export;
	no-vrf-advertise;
	}
customer-1 {
	instance-type vrf;
	vrf-import reject-all;
	vrf-export aggr-export;
	interface foo;			/* switch interface again*/
	routing-options auto-export;
	no-vrf-advertise;
	}
customer-2 {
	instance-type vrf;
	vrf-import reject-all;
	vrf-export aggr-export;
	interface foo;			/* switch interface yet again*/
	routing-options auto-export;
	no-vrf-advertise;
	}
"
Sorry, if curly brackets aren't where they are supposed to be :-)
I would say the Juniper router will bark on someone attempting such configuration. But - depending on what someone is trying to achieve there are other ways of getting the same result. And - depending on the POW, one may or may not call this a workaround.  
HTH,
Cheers
Alex

-----Original Message-----
From: Pedro Roque Marques [mailto:roque at juniper.net]
Sent: 19 October 2005 21:18
To: Alexander Arsenyev (GU/ETL)
Cc: juniper-nsp at puck.nether.net
Subject: Re: [j-nsp] l3vpn


Alexander Arsenyev (GU/ETL) wrote:
> This probably will work but let me recall what the original question was -
> "Can we configure multiple vrfs for a single interface?"
> The config below implies that interface on [pe] facing [aggr] is in routing-instance "aggr", or, in other words,
> single vrf named "aggr" is assigned to the interface on [pe] which faces [aggr].
> So the answer I guess would be "single interface could have only 1 VRF assigned but there
> are workarounds for the specific circumstances".

I sort of disagree w/ the "workaround" comment.

If one considers a routing-instance to imply a particular destination 
lookup table, then by definition a logical interface has a single 
destination lookup table.

For applications where you want "split" particular patterns of traffic 
into different table lookups this is achieved via a classification stage 
before the destination table lookup.

So, i'd argue that the answer to your question is that the concept of an 
interface in multiple vrfs doesn't really exist. Or at least i don't 
understand it.

You can build a lot of applications on top of JunOS if you understand 
what the basic building blocks are. A "routing-instance" is a collection 
of resources that implies both a set of control routing tables and a 
given forwarding path.

   Pedro.