Use Backup link with Static routes

Answered Question
Mar 7th, 2008
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My client has network setup as in diagram. R0 is the router connected to the LAN and R1 and R2 are connected to different service providers. Currently R1 and R2 are the routers running bgp with providers.

Traffic shifting is done from the R0 with default route pointing towards either R1 or R2 when one of the providers link goes down.

My question is that is there a way I can make sure traffic is automatically shifted from R0 without manually changing the default route. I dont want to run BGP on the R0 router connected to LAN.



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Correct Answer by Joseph W. Doherty about 9 years 4 months ago

What I had in mind was http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html#wp1072790, but from what you wrote, it appears you might not want to do anything on R1 or R2, but limit everything to R0.


If that's the case, Robert's suggestion of using routing tracking with SLA, might help. See http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtpbrtrk.html and http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml

Correct Answer by robertblasey about 9 years 4 months ago

How about route tracking? you track the route of your isp transfer subnet - Another idea: maybe some IP SLA with ICMP-Echos and tracking of your IP SLA?


Robert

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thiru.vel10 Fri, 03/07/2008 - 18:53
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Configure the Policy Based Routing and Policy MAP in router0. It may help you.

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robertblasey Sat, 03/08/2008 - 04:54
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How about route tracking? you track the route of your isp transfer subnet - Another idea: maybe some IP SLA with ICMP-Echos and tracking of your IP SLA?


Robert

Joseph W. Doherty Sat, 03/08/2008 - 06:21
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Assuming R1 and R2 share a common segment:


Assuming R1 and R2 have complete external routes, you could place a default route on R1 pointing to R2 and the converse. Loss of one router's external routes would redirect all its traffic to your other externally connected router.


Assuming R1 and R2 again have complete external routes, and have the resources for another instance, another possible method, run iBGP between R1 and R2. Each will know about the alternate path. (They will also be able to redirect traffic if the other provider has a better path.)


PS:

A common segment between R1 and R2 isn't required, but if redirected traffic from R1 to R2 transits R0, R0 will have to be configured such that it doesn't subject that traffic to using the default route.


PPS:

Other possible methods, if R1 and R2 don't have complete external routers, floating routes tracking on both R1 and R2, again with redirection to the other. Both R1 and R2 sourcing a default route advertized to R0 via an IGP (not BGP), but withdrawn if they lose the outbound path.

hasnain321 Sat, 03/08/2008 - 15:03
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Thanks to all for reply


Josheph I am recieving full routes on both routers and they are private networks running MPLS VPN circuits on both networks.

Putting a default route on each router towards each other is not possible.Can you explain a little about the floating routes traking?

I want to control the traffic shifting from the Core router R0 in this case, so that it directs any incoming traffic towards R1 or R2 depending upon whichone is up now

Appriciate your response

Correct Answer
Joseph W. Doherty Sat, 03/08/2008 - 16:10
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What I had in mind was http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html#wp1072790, but from what you wrote, it appears you might not want to do anything on R1 or R2, but limit everything to R0.


If that's the case, Robert's suggestion of using routing tracking with SLA, might help. See http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtpbrtrk.html and http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml

hasnain321 Sun, 03/09/2008 - 19:31
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Hi Joseph and Robert's


Thanks for your help. I have been able to do the task through SLA. Thanks for your help

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