I have a 2620 Cisco Router with only one Fastethernet port Now I have two internet gateways. I want to config my router as when primary routing fails second routing automatically start to route all my packets. When I set 2 IP route command in my router then I check I see it work well but when peer IP on primary routing is down it can not change to second routing until I remove first route command.In the following I write my setting. How can I set it?

interface FastEthernet0/0
  ip address secondary
  ip address

ip route
ip route 100

If you are not running BGP and annoucing your own routes to both ISPs (This is quite involved) then you can look into using IP SLA. Basically you would ping both default gateways, if one can't be pinged it fails over.

There is an example configuration here on the cisco support forums.

  • Dear Kyle, Thank you for your answer but unfortunately Cisco 2620 cannot support SLA – Kamal Miresmaeili Dec 30 '10 at 10:42
  • Actually, the Cisco 2620 can, I'm sure I've done it before, mind you, I think I was running 12.4T Advanced IP Services – Tom O'Connor Dec 30 '10 at 15:55

A little while ago, I was looking at doing something similar with a cisco technology known as Optimized Edge Routing (OER), but I never actually got as far as configuring it. It looks like that's the right kind of thing to do, but without more certainty on the technical implementation, it's difficult to say. Certainly one possible starting point though.

I'd be tempted to knock up a simulation in GNS3 to begin with, and try out some of the OER configurations, before implementing it on real hardware (Assuming your IOS version supports that feature set.)

  • OER is a great feature but maybe overkill in that case. – petrus Dec 28 '10 at 14:20
  • Perhaps. I was told by a friend who is a CCIE, that OER is the best practice thing to use in this case.. Heh – Tom O'Connor Dec 28 '10 at 19:38
  • Dear Tom unfortunately Cisco 2620 cannot support OER – Kamal Miresmaeili Dec 30 '10 at 10:44
  • Boo. That's a shame. What IOS release are you running? (show ver) – Tom O'Connor Dec 30 '10 at 15:54
  • Dear Tom, It's Version 12.3(22). and I donot have enough space in my Flash to upgrade it (My router flash has only 8MB) – Kamal Miresmaeili Jan 3 '11 at 12:50

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