[j-nsp] l3vpn

[Pedro Roque Marques]

Alexander Arsenyev (GU/ETL) wrote:
> 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:

No. And i don't understand which behaviour you would expect from such 
configuration.

Are you expecting the packets to be replicated 3 times and switched 
around into each instance ? If not, what sort of semantics do you have 
in mind ? i.e. in your view what would happen to a packet ?

   Pedro.

> [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.