Hi Rob, it is used in an mpls-based vpn scenario, where the ce speaks ospf with the pe. In order to enable routing to remote vpn sites, the pe has to redistribute mbgp prefixes into ospf with the DN-bit set. The DN-bit is used as a loop prevention mechanism, because if an ospf update with the DN-bit set would somehow reach the pe, it should not accept the update into the vrf again.
However, let's say you have vrf lite with ospf to the pe configured on the ce, this becomes a problem. Because the ce will not import any routes that have the DN-bit set into the vrf and you would not be able to route to the remote vpn sites. By configuring the capability vrf-lite command, the filtering rule is relaxed and the pe routes will be imported into the vrf on the ce. Therefore, to answer your question, you would see the DN-bit set on lsas received from a pe that redistributes mbgp routes into ospf. HTH Marcel On 14/05/2010, at 11:04 , Robert Simmons wrote: > All, > > Can anyone shoot me a quick scenario where I would need to use the capability > vrf-lite command? I need something where I can actually look at debugs and in > the ospf database to see the DN bit checked? > > Thanks > > -Rob > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
