router ospf 3900 15.1 default information originate

[farooq_0923@hotmail.com]

Hi All

Need little help with troubelshooting loop caused by ospf default injection command....we have two wan edges injecting default route (not always keyword added) via ospf into lan and learning default route from bgp... both routers has one lan port connected to core switch....now when one router lose wan connectivity loop is created because default route is cleared by router 1 as it loses its bgp defalt route and ibgp default route is put into rib failure because default route is learnt  via ospf as well...now i know ospf wont inject default route into lan if its learnt from same procvess id ospf , it has to learn default route from another routing protocol or another ospf process but its not exhibiting correct behaviour...in stable conditions when i do show ip ospf data adv (peer IP) on wan edge i dont see any default route coming from core switch but when i do same command on core switch i can see type default route is learnt from both wan edges...can someone poingt in right direction....Labbed it in GNS3 and worked fine but production causing issue ta

[Philip D'Ath]

I can't get your connectivity clear in my mind.

Each WAN edge, how many conenctions does it have?  Once to core network.  One to WAN.  Does it have another?

OSPF: What is it talking OSPF to?  Core and WAN or just core?

BG: What is is talking BGP to?  WAN?  Something else?

[farooq_0923@hotmail.com]

Hi P.dath

I have two  wan edge routers, each with two evc's (two ebgp to provider) and receiving two default route. i have IBGP connection via lan switch (ospf route to neighbor ) to other ibgp router. they both inject default route with same cost (no always keyword) to in lan...so we have two core swicthes each has one port connected to each edge router..other day we had both evc go down on one edge router so it wasnt receiving default route via ebgp anymore and we expected the router with both circuit down to stop advertising default route into lan but it was still advertising default route. we lab and found that ibgp default route was in rib failure as default rroute injected by ospf (secondary router) was received by this wan router (with outage ) and prefered due to AD which is fine but we didnt expact i to inject default route....router with outage was receiving Default route from lan because other wan edge was advertising it and also injecting default into lan cuaisng loop...in lab enviroment when goes down wan edge prefers and accept default route from core switch which was given to core switch by other wan edge router....but it never inject default route back into lan....let me know if you need clarification ta

[farooq_0923@hotmail.com]

Hi Philip D'ath

Found problem, General rule for ospf default originate is to have a default route from extrenal source but when you appply route it  changes that. thanks