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BGP & Static Route at 7204 VXR Router

We are in the midst of implementiing the BGP system for our internet access.

Currently we have 2 upstream providers connecting to the router (1xE3 & 1xFE) and is running on static IPs.

We are adding another upstream provider for our BGP connection. (We have our own AS #.)

We have tried activating the BGP connection at the router. Once the router starts capturing the BGP routing tables, the static route went down.

I would like to find out whether i can use the same router to run both the BGP & Static at the same time for my company.

Regards,

Johnny

3 REPLIES

Re: BGP & Static Route at 7204 VXR Router

Hi

The static route would always take preference to the BGP route unless you have administrative weights configured with your static routes.

I had a setup where i setup a BGP conenction with the provider but still using the static routes for the old connections and IP address.

What are the route prefixes you are receiving from the provider. Best would be to receive only the default route from them and manipulate with the help of weight or local preference.

HTH

Narayan

Gold

Re: BGP & Static Route at 7204 VXR Router

Depends what you mean the static route goes down.

I assume you are using default route to your 2 current ISP. If you take a full bgp route table from your new ISP the default route will in effect not be used. More specific prefixes that you learn from your new ISP always are preferred. You should still see the default route in the routing table.

You could have your new ISP only give you default route via bgp and the static default route will override the one learned via bgp.

There longest prefix match is fundimental to how the router works and your only option if you must prefer a more general route over a specific one is to use policy routing.

Re: BGP & Static Route at 7204 VXR Router

Hi Jonny,

can you post the config for the static route and also describe what exactly you mean with "the static route went down".

Did the traffic flow go to the new provider only? Well in case you have a static default route and the full internet routing table through BGP in place, this would be what I expect. The underlying reason is, that a router will always pick the longest match from the IP routing table. As your default route is the "shortest match" for all networks learned through BGP, traffic will not follow it as long as there is a more precise network learned through BGP.

To redirect some traffic using static routes you would have to create the same or longer prefix length as a static. Example of show ip route (look similar to):

A)

B 1.0.0.0/8 Serial1

S 0.0.0.0/0 connected to Serial0

traffic to 1.0.0.0/8 goes out through Serial1 because of the BGP route

B)

B 1.0.0.0/8 Serial1

S 1.1.0.0/16 directly connected to Serial0

traffic for 1.1.0.0/16 would go through Serial0, all other traffic to 1.0.0.0/8 would go through Serial1

Hope this helps! Please rate all posts.

Regards, Martin

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