OSPF Help

[jonhill]

We have just installed the MPLS circuit and want to start routing some traffic over it, we've got backups working over it using PBR but we want to put some more critical traffic over it so would like to be able to route over MPLS as default but if the MPLS fails it routes the traffic over the WAN. 

My first thought was OSPF but I've had not exposure to OSPF and wondered if anyone could give me some pointers on how I would go about configuring OSPF for this scenario.

Routing to the WAN is all static using the Gateway of Last Resort the WAN itself is OSPF and RIP v2 but its all managed for us and we can't make any changes to the way the routing works (Don't Ask, its very painful at times :-))

See below a basic diagram of the network.

Any help would be much appreciated.

Thanks

Jon

[Julio E. Moisa]

Hi

You can use OSPF Sham-link to have a backdoor as backup, please check these links:

http://networkinferno.net/ccie-study-ospf-sham-link

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/15-sy/iro-15-sy-book/iro-sham-link.html

Hope it is useful

:-)

[jonhill]

The WAN is point to point circuits in a ring and not an MPLS cloud. So not sure the SHAM link would work in our scenario.

Thanks

Jon

[chrihussey]

You could establish a GRE tunnel across the MPLS and then establish OSPF peers across that. You may have to tweak mtu and mss, and depending on the platform and amount of traffic there may be a performance hit. Things to consider but do-able.

Hope this helps.