MPLS P-to-PE OSPF Inter-Area failover

[ar]

Hi Guys.

I am simulating a MPLS core using OSPF for the control plane IGP.

Here's the setup:

Area 0 - backbone

Area 1 - PE routers in location A (PE-A)

Area 2 - PE routers in location B (PE-B)

Network is running MPLS/VPN

Here are the requirements:

1. There will be nxGE links between PE-A and PE-B for better latency  requirement and bypass Area 0 for Location A<>B  destined traffic

     - I can probably use a new direct route between PE-A and PE-B to establish MP-BGP.

2. When Area 1 to Area 0 links are down, Area1 should failover via Area 2.

    And when Area 2 to Area 0 links are down, Area2 should failover via Area 1.

    - I can probably use virtual-links here...But I dont want to complicate things.

Any recommendations on better design?

Thanks

[Reza Sharifi]

Hi,

The simplest solution for this design with a few routers is to put all of them in area 0. There is really no need to complicate things with multiple areas.

HTH

[ar]

Thanks.

I am just thinking on stability if I increase more routers in area0.

I have about 20 routers already in the backbone area. If I will merge area1 and area2 into it, it will be about 24 routers in the backbone area, all 7600 boxes....

[Reza Sharifi]

A long time ago the rule of thump was that you can have up to 50 routers in one area. This was at the time that the routers and switches had low CUP speed and memory.  Now days, the router and switches are powerful enough that can handle the database of more than 50 routers.  I don't think this is going to be an issue with 24 routers, specially since you already have 20 routers in one area.

HTH