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Devinder Sharma
Beginner

Injecting two default routes via ospf into service provider MPLS

Hi All,


We have multiple sites that are linked via MPLS (L3) circuits. We have good size circuits for Internet at two main sites (HQ and QC) and smaller sites come to HQ site to go to internet. We are running ospf (Cisco L3 switches) with service provider (ME3400) at these two main sites and service provider then redistributes routes back into MPLS via BGP and then smaller sites ME3400 learn these routes.


I am injecting default routes from HQ and QC, but Telco is only redistributing default from HQ. So large pipe Internet at QC is not being used effeciently. Also if MPLS at HQ fails, then we are told, we need to call Telco and they will make change in their network to now start distributing default from QC.


It was my understanding that telco can use BGP communities and advertize one default as prefered and second with higher cost, so that failover can occur automatically. And that they can also set up so that west cost sites use HQ and east cost sites can use QC for going to internet, but they say it is not possible.


At the least, can I do something like this at my end for failover for internet, in case MPLS at HQ goes down (soon we will be setting up a point to point VPN tunnel between HQ and QC so that MPLS failure at HQ will trigger advertisement of HQ routes over tunnel via QC into MPLS, so other sites can then come to HQ thru QC over this tunnel.


At QC Cisco router (to detect loss of default route from HQ and then start advertizing default from QC)

router ospf 1

default-information originate always route-map From_HQ

exit

ip access-list standard From_HQ

deny 0.0.0.0

exit

route-map From_HQ permit 10

match ip address From_HQ

exit

Please advise.

Thanks in advance.

3 REPLIES 3
Varun Uniyal
Beginner

If your provider is blocking default-route from the QC site then there is not much can do about it except set up GRE tunnels and advertise default-route through it so that small sites can come to QC over the tunnel to go to the internet.

milan.kulik
Advocate

Hi,

your provider does not seem to be very flexible...

Aren't you able to change the peering with him from OSPF to BGP?

You would have much more possibilities to play with your routing preferences then.

BR,

Milan

Thanks Milan and Varun for your insight.

Telco will not allow BGP peering. And I don't think, they are blocking default route advertisement from QC. They may simply be reject it, if there is already one from HQ. But we have not been able to test it and it may be working if HQ MPLS to go down.

Assuming they only allow default route from QC if one from HQ is not coming, will my ospf  conditional default injection configuration work?

Appreciate again.