[c-nsp] Routing Question

[Tony]

Hi Joe,

You don't need MPLS to run VRF's. A VRF is just a separate routing instance that is kept separate (like a VLAN at L2). You can run VRF's locally on the one box even on a low end ISR if you want to try it out. 

I think the suggestion would be that if you had two route tables (each in it's own VRF) then you could manipulate them separately and have whatever BGP preferences you wanted in each one. You could then push the traffic (using source routing) from each of your subnets into the correct VRF where it would use the routes in that VRF.

This would be the same as if you had two separate routers with one of your source address ranges on each and had different BGP policies on each router. Using VRF would just allow you to do it on one box instead of two.


As Gert suggested, would be hard on memory though if you wanted to put full tables in each VRF. This approach would also be fairly complex, especially if you don't want to think about VRF's.


regards,
Tony.
 


--- On Fri, 3/6/11, Joseph Hardeman <jwhardeman at gmail.com> wrote:

> Hi Gert,
> 
> Thanks for the reply, I was hoping there was some way to do
> it with
> Local-Prefs or weights setting the BGP routes from peers
> into a group and
> then selecting that group from the routing table for the
> internal IP Range I
> want to use those routes.  I presume there is a way to
> setup VRFs to do
> this?  Or how would that work?  I believe VRFs
> are specific for an MPLS
> network and I have never touched or set one of those up
> before.
> 
> Thanks
> 
> Joe
> 
> On Thu, Jun 2, 2011 at 2:02 PM, Gert Doering <gert at greenie.muc.de>
> wrote:
> 
> > Hi,
> >
> > On Thu, Jun 02, 2011 at 08:14:32AM -0400, Joseph
> Hardeman wrote:
> > > I am wondering, is it possible to route traffic
> based on the Source IP to
> > > specific BGP learned routes?  For instance,
> if I have IP Range
> > > 2.2.2.2/24that I want only to use routes learned
> from peerings with
> > > say AS 444, 555,
> > > 666.  But I want to have IP Range 2.2.2.3/24
> use the routes learned from
> > > peerings with say AS 111, 222, 333.  I know
> I can do PBR and set the
> > > next-hop based on the source IP but it appears
> that even with multiple
> > > entries in that route-map statement it will
> choose one out of the list
> > and
> > > use that by default and not choose the best path
> learned from the
> > neighbors
> > > I want it too.  Can this be done with
> local-prefs or weights?
> >
> > No.
> >
> > You'd need to do VRFs (and having a full table in
> multiple VRFs is going
> > to eat lots of memory).
> >
> > gert