INE Vol 1 - Lab 11 - finished - OSPF Sham Link.

The gist of this lab was when using OSPF to interconnect 2 remote sites to 2 PEs and they have a back door link to each other (ie a private line) then because the routers are in the same area 0, routes within an area are preferred over routes that are INTER area and OSPF has a lower AD then iBGP. To get around this, between the two PEs you can create an ospf sham-link and then change the cost of the backdoor link to be worse.

config:

Router1(config-if)# area 1 sham-link 10.2.1.1 10.2.1.2 cost 40

verify:

show ip ospf sham-links