Route Reflector Client Design Question

Fri May 4 12:58:14 UTC 2018

Hello,

In order to accept only the default route, I assume that you want to have internet access to the ASR920 inside a vrf. ?!?
 If this is the case, your consideration of the default route and the TCAM size is correct. But, if there is internet traffic between the PE2-PE3 in the same vrf , then I think that its ok to leak more specific prefixes from PE2 to PE3 (by using specific Route Targets) from the CORE1 & CORE2 (RR).

Unless there is something that I miss,  option #2, is more favorable.

Michalis Bersimis

-----Original Message-----
From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Erik Sundberg
Sent: Friday, May 04, 2018 9:02 AM
To: NANOG
Subject: Route Reflector Client Design Question

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....

Thanks

Erik

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