From: Peter van Oene (pvo@usermail.com)
Date: Wed Feb 05 2003 - 14:29:08 GMT-3
At 10:16 AM 2/5/2003 -0700, Joe Martin wrote:
>Peter,
>
>Could you please explain to me what the purpose of a route reflector is if I
>have configured the no bgp client-to-client reflection command. If the
>reflection server isn't reflecting routes between clients, what's the point?
Most medium to large BGP networks employ a hierarchy of route
reflection. In these cases, it is normal and indeed necessary to maintain
multiple route reflection clusters. Therefore, without the route
reflector, members of a cluster would only learn intra cluster routes. It
is the route reflectors role to bring extra cluster routes into the cluster
and to similar export cluster routes to those routes beyond the cluster.
Since that test is pretty confusing sounding and heavy on the cluster,
consider the below network.
--ebgp-A-------B--------C-------D-ebgp
| |
E--------F
/ \ / \
G H I J
In the above, B,C,E,F represent the IBGP core of this simple network. A and
D represent two peering routers in network while G to J are regional market
routers. In this case, you would have BCEF IBGP directly, and have E
reflect to G and H, and F reflect to I and J. Also, B would likely reflect
to A and C similarly to D. If G and H chose to peer directly, you would
enable no client reflect on E, but you will still need E to advertise G and
H's routes to the rest of the network, and to import routes from the rest
of the network for G and H.
The above isn't meant to be a best practise network and only an example ;-)
Pete
>Is this just used as a migration tool away from or into a route reflector
>design?
>
>TIA,
>
>Joe Martin
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Peter van Oene
>Sent: Wednesday, February 05, 2003 8:44 AM
>To: Brown, Patrick (NSOC-OCF}; ccielab@groupstudy.com
>Subject: RE: Route Reflectors and Peer Groups
>
>
>At 09:31 AM 2/5/2003 -0600, Brown, Patrick (NSOC-OCF} wrote:
> >This is what is was talking about from the 12.1 config guide documentation
> >under BGP.
> >
> >By default, the clients of a route reflector are not required to be fully
> >meshed and the routes from a client are reflected to other clients.
> >However, if the clients are fully meshed, the route reflector does not
> >need to reflect routes to clients. To disable client-to-client route
> >reflection, use the no bgp client-to-client reflection command, beginning
> >in router configuration mode:
>
>This is accurate
>
> >Note: If client-to-client reflection is enabled, the clients of a route
> >reflector cannot be members of a peer group.
>
>This is odd, but may be an ios limitation. In Juniper, one applies
>no-client-reflect to the peer group. It is quite normal to have all
>members of a reflection cluster in the same peer group.
>
> >What I interpret from this statment,is that RR can't have clients that are
> >in a peer group they configured(logical).
>
>I would tend to agree with your interpretation, though I'm not sure what
>the technical limitation is.
>
> >Tx,
> >
> >Patrick B
> >-----Original Message-----
> >From: Peter van Oene [mailto:pvo@usermail.com]
> >Sent: Wednesday, February 05, 2003 7:29 AM
> >To: ccielab@groupstudy.com
> >Subject: Re: Route Reflectors and Peer Groups
> >
> >
> >At 10:03 PM 2/4/2003 -0600, Brown, Patrick (NSOC-OCF} wrote:
> > >Question
> > >
> > >Is it true that you can not have neighbors in a peer-group and be
> > >their route reflector at the same time?
> > >If this is true, should the "no bgp client-to-client reflection" command
> > >take card of this.
> > >I have seen labs were this configuration happened.
> >
> >Are you asking if clients in a reflection cluster can be neighbors
> >themselves? peer-groups are just a configuration tool and don't actually
> >affect the performance of BGP external to the router. If this is that
> >case, then yes is the answer, and no client-to-client-reflection will stop
> >the reflection server from reflecting intra cluster routes back to clients
> >(since they will be learning these directly)
> >
> >Pete
> >
> >
> >
> >
> > >Tx,
> > >
> > >Patrick B
> > >.
> >.
>.
.
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