Controlling default route OSPF

[roger perkin]

Our network consists of 2 Internet routers one at head office and another at our DR site.

The current setup is that the DR router has an interface cost of 30000 on the outgoing interface to the ISP to which we are running OSPF.

The behaviour is all internet traffic will exit via the head office Internet link. If this router goes down all internet traffic will go via DR site and this works, but only in the event of a router failure or the default information is not advertised.

The DR link has now been beefed up and there are about 200 users working at the DR site, I want to influence the OSPF to route all users at the DR site (PC1) to go out of the DR internet link.

Most of the head office users are in Area 0 which spans two sites.

What will happen if I remove the ospf cost of 30000 on the DR router.

Picture attached

[Marwan ALshawi]

what area number and type etween the DR internet router and router connected to PC1 ?

one simple thing you can try is increase the ospf cost of the interface of router beside PC! connected to the ABR under it

to somthing hgiher than 30000 such as 50000 this way way the cost from the head office to the DR will stay too high

however the routerconnected to PC1 will see the cost to the DR internet 30000 less than over the backbone 500000

and let me know the result

good luck if dose not work increase the cost of the link connteting the the DR ABR to the dirctly connected router in the backbone

[roger perkin]

DR ISP router to PC router is Area 4 - not sure of type? (no special config so whatever the default is)

I have just set this up in GNS and removed the OSPF cost on the DR router,

All the routers on the right route out of the DR router, and all the routers on the left go out of the Head Office

Is this text book OSPF metric?

I need to understand exactly what it is doing before I make the change.

I will try your suggestions and report back - good way to learn OSPF!

Thanks

roger

[Marwan ALshawi]

Hi roger

yes it is working as expected this is metric but in ospf terms it called cost the router when it calculate a route ( assuming same type interms of inter ot intra area and same subnet length ) cost comes into effect and the router calculated in the inbound direction not outbound

good luck

and if helpful Rate