[j-nsp] BGP route-reflection question

['Dmitri Kalintsev']

Hannes, Guy:

Thanks for an info. It is nothing critical, just something to remember I
guess. :)

Guy: in case when client is using its point to point link address to
communicate with RR2, its session will go down with the link. Sorry for not
specifying this in my "case". :) Yes, I know that it's a good practice to
talk Lo0 to Lo0. :)

P.S. I've noticed yesterday that the other vendor is now also says that
having more than one RR in the same cluster is "not recommended". *Sigh*,
the world has changed, hasn't it? ;)

SY,
--
D.K.

On Wed, May 28, 2003 at 05:15:54PM +0200, Hannes Gredler wrote:
> i second guys' assessment: having RRs with different cluster-IDs is the way
> how we recommend setting up route reflection;
> 
> /hannes
> 
> On Wed, May 28, 2003 at 09:15:06AM +0100, Guy Davies wrote:
> |  
> | -----BEGIN PGP SIGNED MESSAGE-----
> | Hash: SHA1
> | 
> | If there is a connection between RR1 and RR2 then the client will maintain
> | iBGP connections to both of the RRs.  Remember, iBGP is inherently capable
> | of multihop.
> | 
> | The other possible solution for getting RR1 to accept routes from RR2 is to
> | give them both different cluster IDs.  There is no requirement for all RRs
> | associated with a single "cluster" to have a common cluster ID.  Therefore,
> | each RR would see the other's cluster ID in the cluster list and accept the
> | prefix.  However, it would still be receiving a better path direct from the
> | client (shorter cluster list) :-)
> | 
> | To answer your question.  Intracluster reflection is client-to-client
> | reflection (i.e. routes learned by RR from client A will be reflected to
> | client B) so there is no requirement for a full mesh within the cluster.  If
> | you want to turn this off then you can do so with "no-client-reflect" in the
> | particular group.
> | 
> | Regards,
> | 
> | Guy
> | 
> | > -----Original Message-----
> | > From: Dmitri Kalintsev [mailto:dek at hades.uz]
> | > Sent: Wednesday, May 28, 2003 8:00 AM
> | > To: juniper-nsp at puck.nether.net
> | > Subject: [j-nsp] BGP route-reflection question
> | > 
> | > 
> | > Hi All,
> | > 
> | > Let's imagine that I have two straight ipv4 BGP route 
> | > reflectors in the same
> | > cluster, say R1 and RR2. Now imagine that I have a reflector 
> | > client, which
> | > is:
> | > 
> | > a) Connected to both of them via dedicated point to point links;
> | > b) Advertising the same routes to both of them.
> | > 
> | > Now imagine that one of the point to point links (say client 
> | > to RR1) has
> | > failed. Client would still advertise it's routes to the RR2, 
> | > and RR2 would
> | > readvertise them to RR1.
> | > 
> | > The experience that I had with other vendor's equipment is 
> | > that RR1 would
> | > not accept the client route advertisements from RR2, because 
> | > it would reject
> | > them having seen it's own cluster ID in these. The only way 
> | > to make this
> | > work was to remove the cluster ID (cluster list is used 
> | > instead to prevent
> | > routing loops).
> | > 
> | > In JunOS, it is a prerequisite and the only way to configure 
> | > route reflector
> | > client by setting the cluster ID in the bgp group to which the client
> | > belongs.
> | > 
> | > http://www.juniper.net/techpubs/software/junos/junos57/swconfi
> | g57-routing/html/bgp-config37.html#1015846
> | 
> | states:
> | 
> | "By default, the BGP route reflector performs intracluster reflection
> | because it assumes that all the client peers are not fully meshed."
> | 
> | Could anybody please clarify to me how this is implemented in JunOS and this
> | "intracluster reflection" is?
> | 
> | SY,
> | - -- 
> | D.K.
---end quoted text---

-- 
D.K.