Single Router Solution for 2 Service Providers

[vk.net357]

Friends,

I have a 2951 router and 2 service providers, with no firewalls and we dont want to get firewalls, now we need to make a failover configuration for those two service providers, any suggestions please.

Thanks

Vikram

[ghostinthenet]

As long as you have two WAN interfaces available on the unit, you can create separate NAT definitions and use either IP SLA and object tracking or route tracking to create a failover route between the two. Are you running any kind of routing protocol with your ISP?

[vk.net357]

Thanks Jody,

we are running OSPF on this router.

[ghostinthenet]

Are you exchanging OSPF routes with your ISP? If not, are you running BGP with them?

[vk.net357]

we are exchanging OSPF routes with ISP

[ghostinthenet]

That makes things simpler. Assuming that the ISP is providing you a default route via OSPF, do you expect that the second ISP will do the same or will they just be running static routing?

[vk.net357]

Second ISP also will do the same thing.there will be no static routing on second isp..

we have our scenario in the following way:

Router  ------2Modems-------------ISP Provider------------WAN Router

i am sorry for such a bad explanation,

the 2 modems are always up , so we need to get a solution in such a way that if a link fails from 1 modem to the ISP provider, the second link from ISP provider to 2 modem should be up and running, i am thinking this can be done if we can put IP SLA, any advice on it .

[ghostinthenet · Accepted solution]

Okay... as long as you want a full failover configuration, you can just run two different OSPF processes and give the backup one a higher administrative distance than the first one. Make sure that each process is only advertising the routes belonging to the appropriate ISP and you should be good. This is assuming that each ISP is only sending you a default route.

If they're both feeding you a default route, there should be no need for an SLA. When the primary connection drops, the backup's default route will take over automatically.

[vk.net357]

Thanks Jody, will work on it and update you if any thing comes up.

[vk.net357]

Hey Jody,

I configured my lab router with IP SLA as follows

track 1 ip sla 1 reachability

track 2 ip sla 2 reachability

ip sla 1
 icmp-echo <ISP1 Ip address> source-interface GigabitEthernet0/0
 threshold 3
 timeout 1000

 frequency 180

ip sla schedule 2 life forever start-time now

ip sla 2
 icmp-echo <ISP2 ip address> source-interface GigabitEthernet0/2

frequency 180
 threshold 3
 timeout 1000
ip sla schedule 2 life forever start-time now

ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0 track 1
ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/2 10 track 2

in this scenario, if i connect through console to the router, test is successfull and if i put that router in the network, and manually as soon as i say Gi0/0 shutdown, router crashes

any suggestions ?

[ghostinthenet]

It shouldn't crash. I would make sure that you're using the latest release withing the software version you're running.

If you're running OSPF with your providers, why are you using SLAs and static routes? You should be able to prioritize your routing without resorting to this sort of configuration.

[vk.net357]

Hey Jody,

I am sorry there was a miss communication in the previous discussion, we are not running OSPF with our providers, we are using Tunnels.