what are the pros and cons using ospf as the PE/CE protocol

sanjoy2006 · ‎07-03-2008

pros and cons using ospf as the PE/CE Protocol

lee.reade · ‎07-03-2008

Hi,

Well in short,

pros:

well deployed protocol with good user experience

fast convergence

no redistribution required on ce side

cons;

type 1 & 2 routes (O) from one site are known as type 3 summary routes (OIA) in the other site

you need a sham link configured on the pe routers to get the routes as type1&2 at each remote site

If was deploying mpls vpn, i would use either ospf or bgp as pe/ce protocol.

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ospfshmk.html#wp1024995

HTH

LR

sanjoy2006 · ‎07-03-2008

Thanks for reply ,

Under cons you have explained about Intra route(sham link)

any explanation in case of VPN TAG and Down bit .

lee.reade · ‎07-03-2008

With regard to down bit, it is automatically set by the PE when redistributing BGP routes into ospf as type 1/2/3. The tag field is copied from the bgp as number, into the tag field for type 5/7 (external) routes.

These are both to ensure that a route redistributed into ospf from bgp, cannot go back into bgp on another pe at same site.

This is all done automatically, so you dont need to worry about them.

HTH,

LR