From: Kash (kash2331@yahoo.com)
Date: Sat Apr 12 2003 - 10:38:01 GMT-3
Hi
If i may so comment.
%
Route reflector %
---------------------------------
| | % |
| | % |
| | % |
RRc RRc % non-client
%
This is the way that I picture what u are saying. The
RR has three routers hanging of it. 2 RRc's and one
non-client. Now what i have understood from Doyle and
Halabi is that the non client basically sees the RR as
the only router. Thats why I have put these % sign. If
the RRc knows about a route it tells it to the RR
which inturn tells it to the non-client. (please do
keep in mind that BGP is TCP based so we are not
talking of physical connections, the non-client might
even be connected directly to the originating RRc).
For the non-client it will get the route (with the
next hop of the originator) and as i said being not
based on physical connection it will some how know how
to reach that route by IGP as this is just one AS.
One point also to mention here is that since this is
just one AS BGP cannot use AS_Path as a loop avoidance
mechanism. So it uses Originator ID and Cluster list.
When a RR sends a route from its clients to its
non-client it adds the cluster ID
Halabi pg 260 and 261(for more details)
Hope this helps
Kashif
Danny Andaluz wrote:What I have is the
following:Route Reflector| | || | |RRc RRc
non-clientIBGP assumes a full mesh. If that non-client
does not have an IBGPconnection to either of those
RR-clients and only has an IBGP connection tothe RR,
then how, if the RR does not have the non-client
configured aRR-client, does the non-client get the
route being advertised to the RR fromone of the
clients? IBGP assumes a full mesh. The RR assumes that
thenon-client has an IBGP connection the clients, so
he would not send theroute (loop avoidance). If the
route reflector reflects the routes to thenon-client
as well, what's the point of having RR's. I'm probably
stillmissing something.----- Original Message
-----From: "OhioHondo" To: "Danny Andaluz" ; Sent:
Friday, April 11, 2003 8:30 PMSubject: RE: BGP
question> Danny>> When you use route reflectors, all
RR's and non-clients have to be in afull> mesh. The RR
clients "hang" off of the RR's. In your scenario you
have aRR> with 2 RR clients. The RR is also connected
to a non-client (a BGP routerin> the same AS that is
another RR or just has IBGP sessions
withnon-clients).>> Since you only have 2 non-clients,
you have a full mesh.>> -----Original Message----->
From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com]On Behalf Of> Danny
Andaluz> Sent: Friday, April 11, 2003 4:05 PM> To:
ccielab@groupstudy.com> Subject: BGP question>>> I
have a question about non-clients in a route-reflector
topology.> Assuming all routers are in the same AS,
you have a hub and spoke topology> where the RR has
three peerings with three different routers. Only two
of> those neighbors are configured as
route-reflector-clients. In Doyle's> routing TCPIP V.
2 pg. 127, it says that if a RR learns a route from a>
RR-client that route will be sent to the other
RR-client as well as the> non-client. I am under the
impression that a non-client is simply a> neighbor
that is not configured as a RR-client in the RR. If
this> non-client was in a different AS, I can see this
happening because that is> EBGP, but IBGP assumes a
full mesh, so how could the RR send this route to> the
non-client? Of course, I'm going on the assumption
that a non-clientis> what I described previously. So I
guess my question really is, what is a> non-client?>
TIA,> Danny
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