Multi-ISP Routing Issue

[balbeer.singh84]

Dear Team,

I am using two ISPs on my Cisco 2901 Router. Gig0/0 is Primary ISP & Gig0/1 is Backup ISP. At any time, both the ISPs are up but being the Primary ISP (having primary default-route), Gig0/0 is forwarding my traffic. At any moment when I am removing the backup link i.e. making Gog0/1 down by removing the cable, the Internet browing stops but only the Ping to public IPs is working. I am surprised why the primary link is also getting affected even I am removing backup link.

Please suggest.

-Balbeer Singh

[PowerBarry43]

Hi

stupid question but is it possible that you have the wrong route as default? you could try using google's public dns servers 8.8.8.8 and 8.8.4.4 and see if that makes any difference as this sounds to me like you are using the dns servers of your backup ISP

Hope this helps!

Barry

[balbeer.singh84]

Hi The routes are correct. I have verified them. Please note, there is not any issue with the auto-failover when both the links are connected (interfaces are up). It is making the difference when the backup interface cable is plugged it from router.

Balbeer.

[PowerBarry43]

would I be correct in saying you have no problems until the backup link goes down, at which point you have ip connectivity but you cannot resolve names? so with the backup link unplugged you type 173.194.41.99 in the url bar and you get google?

[balbeer.singh84]

Even if the backup link goes down logically (link is physically connected), I don't have any issue but if I am removing the physical link, then only I am having issues i.e. it is affecting primary link as well.