OSPF learnt route difference with VOSS.

[Anonymous]

Hi

Hoping someone more clever then myself can help me workout why a route on the Palo Alto shown below (10.119.71.0) is add a route via the EXOS devices on the EOS switches as you would expect, but I am not seeing anything via the VSP.

I think its to do with the same routes via the VSP being seen as type 3 LSA’s?

In essence I am migrating the the L3 links on the firewalls from EXOS to the VSP’s. The whole Data Centre is run North of the firewall. So I want to be careful about moving the L3 links across so not to cause any disruption.

I don’t think there is anything necessarily wrong, as the VSP learned routes will I believe kick in when fully migrated across, but what to fully understand what I am seeing to be sure it is safe.

Many thanks in advance.

Martin

[Miguel-Angel_RO]

Martin,

What are the neighbours on the VSP?

“show ip ospf neig”

[Anonymous]

Hi Mig,

Thanks for getting back.

Here is the output taken from VSP-CR1

show ip route alternative | 10.119.71

***********************************************************************************
                Command Execution Time: Thu May 27 08:52:24 2021 GMT
************************************************************************************
=====================================================================================================
                                       IP Route - GlobalRouter
=====================================================================================================
                                                     NH                      INTER
DST             MASK            NEXT                 VRF/ISID         COST   FACE     PROT AGE TYPE PRF
-----------------------------------------------------------------------------------------------------
10.119.71.0    255.255.255.0   172.20.251.65        GlobalRouter     20     3501     OSPF 0   IB   25

show ip ecmp max-path
************************************************************************************
                Command Execution Time: Thu May 27 08:52:37 2021 GMT
************************************************************************************
====================================================================================================
         ecmp-max-path Info - VRF "GlobalRouter" (Global Routing Table)
====================================================================================================
               ecmp-max-path : 8

Which the output looks identical to just looking at the active routing table.

The route is in the VOSS switch, just seems the on the EOS switch it sees the same route learnt via the EXOS switches differently and VOSS - I think, and not sure why, or how to correct (if that is necessary).

Is it that the EOS switch sees the route via EXOS as interarea and VOSS as external? So EOS is just adding the more least expensive route?

[Miguel-Angel_RO]

Martin,

Probably related with ecmp.

Check this:

show ip route alternative

show ip ecmp max-path

Mig