ISIS and OSPF together

Sun May 12 08:51:07 UTC 2013

Ospf offered as Pe-ce protocol to L3 mpls vpn customers and  Isis as IGP for MPLS Core.

Sent from my iPhone

On May 12, 2013, at 9:41 AM, Glen Kent <glen.kent at gmail.com> wrote:

> Hi,
> 
> I would like to understand the scenarios wherein the service
> provider/network admin might run both ISIS and OSPF together inside their
> network. Is this something that really happens out there?
> 
> One scenario that i can think of when somebody might run the 2 protocols
> ISIS and OSPF together for a brief period is when the admin is migrating
> from one IGP to the other. This, i understand never happens in steady
> state. The only time this can happen is if an AS gets merged into another
> AS (due to mergers and acquisitions) and the two ASes happen to run ISIS
> and OSPF respectively. In such instances, there is a brief period when two
> protocols might run together before one gets turned off and there is only
> one left.
> 
> The other instance would be when say OSPF is used to manage the OOB network
> and the ISIS is used for network reachability.
> 
> Is there any other scenario?
> 
> Glen