Route Reflector Client Design Question

Fri May 4 19:06:59 UTC 2018

You could optimize the packet hop count by making smaller
but more rings. For example, make one ring with
CORE1, CORE2, PE1, PE2, PE3.
And another ring with
CORE1, CORE2, PE4, PE5.

If you configure "route-reflector-client" on the CORE,
and mesh the clients, then you can additionally configure
"bgp client-to-client reflection disable".

However, if the CORE is just sending a default route,
then you probably have default-originate and no RR clients
on the CORE. Then you don't need to disable reflection,
because it's not reflecting anyway. (reflection refers to
the reflection of routes, not reflection of packets).

You could send limited important or heavily used prefixes between
the PEs using route policy without blowing up the TCAM.

Regards,
Jakob.

-----Original Message-----
From: Erik Sundberg <ESundberg at nitelusa.com>

I have a RR Client design question......

CORE1-------------------2x10G-----------------------CORE2
|                                                    |
|                                                    |
|                                10G Ring            |
|                                                    |
|                                                    |
PE1----------PE2----------PE3----------PE4----------PE5

-Core1 & Core2 are RR Reflectors with full IPV4 Tables (ASR9K)
-MPLS LDP Enabled
-IGP is ISIS
-Each PE peers only with Core1 and Core2 as RR Clients with iBGP
-PE's are only receiving a default route from the Core Routers due to TCAM size of 20K (ASR920's\ME3800's)
-The ring does not have that much traffic on it <500m, so I do not want to use additional 10G ports on the Core's and is why I have it in a 10G U ring.
-Primary link to the cores is via the PE1 --- CORE1 Like......... For this discussion the link between PE5 to CORE2 is set up as a backup link.

The scenario is I have traffic between PE2 and PE3. Since the PE's are only receiving a default route from the Cores. Traffic is label switch from PE2 - PE1 - Core1 does a IP lookup at Ingress then label switches back to PE1-PE2-PE3. This ends up being 5 hops and doubling the traffic on the link to the Cores.

My questions is how do I get traffic to go directly between the PE's without going to the Core Routers?

1. Can I enable iBGP between the PE's in a full mesh to allow traffic between the PE's without going to the core's. Or does this break the Route Reflector model?
2. Create a route policy on the Core's advertising routes learned from the PE's back to all the PE's on the ring.
3. Is this one of the down sides to U Rings?
4. Leave it alone and move on to bigger and better things....