Dual ISP

[Network Pro]

Hi,

Consider I have this scenario

ISP1          ISP2

  |                  |

  |___rtr____|

I would like to use ISP1 as primary and ISP2 as secondary. So i thought of using two static routes with higher metric. I also thought about using ip sla. How do i go about about using ip sla with the above scenario. this traffic is tunnelled traffic (Dmvpn) so no outside traffic to internet so need of nat

Thanks

[Mark Malone]

Hey use ip sla with tracking and track a route upstream in the internet with ISP1 , when that route is no longer reachable it will fail to 2nd ISP

quick example with config in this link

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/813-cisco-router-ipsla-basic.html

another option is use both ISP links at same time and allow cef to load balance rather than keeping 1 link redundent

[Network Pro]

Thanks Mark. I am using DMVPN so no nat needed (as all traffic is pushed through DMVPN) - for ISP 1 I have a tunnel interface 1 with source interface as GI0/1 (ISP1) - Will i be able to apply a second souce interface as Gi0/2 (ISP2) under same tunnel interface 1 ? I suspect not.

if I create a second tunnel (Tunnel2) and set ip sla, will the second tunnel be only formed if IP Sla fails ?

[Mark Malone]

hey im pretty sure from what i remember only 1 source per physical interface

the 2nd tunnel should form with or without ip sla

the ip sla is just a monitoring function and working with tracking will just redirect traffic to the 2nd ISP link when a failure occurs , the tunnels should have no dependency on ip sla to form