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New Member

Maximum OSPF processes on a router?

What is the maximum number of OSPF processes that a router can run? In a book I read the following:

"when provisioning for PE-to-CE connectivity, it is important to bear in mind that the current IOS implementation provides a maximum of 32 protocol descriptor blocks (PDBs) per PE router.

One PDB is used per protocol instance, including static and connected.

If OSPF is used for PE-CE connectivity, separate OSPF processes are required (1 per VRF), and 1 PDB is used per VRF where you run an OSPF process."

So does that mean that only 32 OSPF processes can be run on a single router? If someone can confirm this, I would appreciate it!

Thanks

5 REPLIES

Re: Maximum OSPF processes on a router?

Yes that is true. Actually in an MPLS/VPN environment a PE is using "directly connected", "static", IGP (f.e. IS-IS) and MP-BGP. So finally there are 28 processes left for OSPF. Whether one would be very happy with a router trying to run 28 SPF concurrently is another question ... so to my opinion this is not really such a big deal. "only 32" is relative ...

kind regards

Martin

Re: Maximum OSPF processes on a router?

Update:

With IOS 12.3(4)T and 12.0(27)S you can have 32 OSPF processes per VRF.

http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a00801d2d65.html

kind regards

Martin

Bronze

Re: Maximum OSPF processes on a router?

This is totally correct. It is a bit of a bummer but I believe Cisco are attempting to up this limit. Watch this space. Really if you get to connect 25+ customers who are using OSPF then the router should have paid for itself and you can buy another one ;->

New Member

Re: Maximum OSPF processes on a router?

One way to get around this scalability issue is to use BGP on the PE/CE link and to a mutual redustribution of OSPF/BGP on the CE sites (using BGG SSO to prevent loops).

Doing this will on the other hand render the preservement of LSA Types impossible but at the moment there isn't a way to get around the scalability theme :-(

Regards,

David Domjahn

Bronze

Re: Maximum OSPF processes on a router?

as of 26S there is no limit on the ospf processes.

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