Network Design Issues

Unanswered Question
Sep 19th, 2008

Hi Expertise,

I have a Cisco 1841 acting as my core router (with HSRP to another 1841). I have 2 more routers on which MPLS ckt is getting terminated. My branches are getting connected to my LAN via MPLS. LAN users are accessing internet via core route that is 1841. What I want to do is if my core router goes down my LAN internet traffic revert on MPLS ckt. If one MPLS ckt is also down it revert on second MPLS router. Entire LAN have ospf topology. Pls suggest ur valuable output. Is SLA based routing support on this, if yes HOW??

I have this problem too.
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Giuseppe Larosa Fri, 09/19/2008 - 04:39

Hello Ashish,

OSPF routing could be enough to get what you want the two routers where MPLS links are terminated can inject a default-route in OSPF conditioned with a route-map with the reception of a default-route over the MPLS link from the ISP.

on the core 1841 having its own internet connection you can use a default static route that will override the OSPF default routes sent by the CE routers.

When the internet link goes down the static route is no longer valid and the core 1841 will start to use the default routes advertised in OSPF.

You can use a different seed metric to have a hierarchy in usage of the MPLS links or you can load balance over them.


I haven't seen you had already opened another thread for the same issue

I've given a look to the network diagram but I'm not sure to have understood your requirements because on the other end of MPLS links I see branch offices so I don't know if they have their own Internet link as I supposed above

Hope to help


singhashish12 Fri, 09/19/2008 - 04:49

Hi giuseppe,

Thanks for ur reply.

No branch offices dont have IL; they have mpls vpn. Branches suppose to access internet via head office.

This point also i need to figure out, how i can do the same.

Thanks .

Ashish Singh


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