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habbie
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Mon Mar 13, 2006 6:41 am

OSPF configuration for active-active Mode

Mon Mar 13, 2006 7:02 am

We are in process of designing the Network . Following is the design ,

1) Each site will have 2 different service provider for VPN
2) Above link will be terminating on Cisco 3750 Switch .
3) Both the link will be in active and active mode
4) The destination of the packets will be to same Data Center from both the service provider
5) At site will have to 2 subnet and routing will be on PBR such that one network goes to one service provider and other 2 another service provider

Now I have to run OSPF between 3750 Switch and PE router such a way that if one of the service provider is down that trafic is routered thru second service router ..

Need help how to configure OSPF for the same.

geko29
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Mon Feb 06, 2006 5:11 pm

Mon Mar 13, 2006 9:12 am

Are you sure both providers are willing to run OSPF with you? Usually dual-home environments require BGP for 3 reasons:

1)Allows you and the provider to maintain your routing policies without a great deal of manual configuration/tweaking.
2)If implemented properly, prevents your site from becoming a transit zone between provider A and provider B.
3)Does not require redistribution at the border between provider A and provider B, which they're generally not willing to do anyway.

If they're still willing to let you run OSPF, you can manipulate the path costs statically or via route maps to influence outbound traffic at each site, then you'd likewise have to manipulate the metrics at the HQ to guarantee return traffic goes back the same way. Again, this would be easier to do with BGP, as you could simply manipulate local preference and/or MED once and you'd be done.

habbie
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Mon Mar 13, 2006 6:41 am

Mon Mar 13, 2006 11:33 pm

Thanks Geko29 ,

Yes both the Service Provider has agreed to run OSPF for us .

Just to forget to add we will have one routers for each provider terminating at 3750 . Between Switch , CPE and PE OSPF will be running .


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