single node for RR and eBGP dual functionality

[gsidhu]

Hi

Customer has VSS provided by two Catalyst 6800 switches with Sup 2T. For increased redundancy the Catalyst switches are in different computer rooms.

The VSS will provide Route Reflector functionality for 16 nodes over MPLS deployment for 12 VRF's. ie single RR node deployment for 16 nodes/PE's that will be connected to both of the physical 6800 switches over layer 3 port channels.

The VSS will also be connected over eBGP to two different autonomous systems.

Two Questions

I can see the logic in having VSS provide single RR since the physical switches are in different rooms connected to different electrical mains supplies, have redundant links ..etc.

1) Can anybody see any issues with this?

I've only come across deployments that have 2 x dedicated RR; providing RR functionality only so next question:

2) RR and eBGP functionality in a single node; is this supported?

[Philip D'Ath]

What is the possibility of the VSS link being severed?  Are the VSS links diverse?

If the VSS links went down then this could crash and burn big time.  You need to be very confident in those VSS links between the sites.

I don't know the answer to (2).  But RR process IBGP routes - not eBGP, so it seems reasonable it could do both to me.

(1) seems like a rock solid "safe" option to me able to cope with a vast range of failures.

[gsidhu]

Thanks Philip.

I think one potential issue is if the VSS needs to be upgraded to another major release which will require downtime for the whole network since eFSU currently is only supported within major releases:

http://www.cisco.com/c/dam/en/us/td/docs/switches/lan/catalyst6500/ios/SX_SY_EFSU_Compatibility_Matrix1.pdf

So for example you can carry out eFSU from 15.2(1) to 15.2(2) but not from 15.2(1) to 15.3(1)