Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
You may experience some slow load times, errors, and slight inconsistencies. We ask for your patience as we finalize the launch. Thank you.

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

defualt router in opsf


stub is a area in which AS External LSAs are not flooded, in this case ABRs at the stub area use LSAs(network summary) to advertise a single defualt router(destination into the area.

In this case what is the function of defualt router? what does this do?


Sulaiman Ejaz

  • LAN Switching and Routing
Hall of Fame Super Silver

defualt router in opsf

Perhaps the problem here is more about terminology than about real functionality. The default route that is advertised by the ABR into the stub area gives the OSPF routers within the stub area a direction in which to forward packets whose destination is external to OSPF.

Perhaps it may help to think of it in this way: the External LSAs that are not flooded into the stub area represent destinations that are external to OSPF. The OSPF routers within the stub area will have LSAs that advertise all of the destinations that are within OSPF so they can accurately forward traffic to any destination that is within OSPF. But these routers within the stub area do not have LSAs for external destinations. So the ABR sends an LSA advertisement that gives the routers within the stub area an entry that they can use to forward to the external destinations.