Mutihoming dual ISP connections

[puneet_kandwal]

Hi,

I am going to terminate mutiple ISP's connecting on the same 1941 router.

After the router there is a ASA5515X device which will be primarily doing IPS as well as perimeter security..

Behind the firewall there are two servers which are going to be accessed by people in internet.

I want to ensure that the reachabilty to these servers are up even if one of the ISP goes down...

Request you to kindly suggest solution for the same..

Also sending the diagram for the proposed setup for your kind perusal...

Regards

[Alessio Andreoli]

Hi Kandwal,

ip route 0.0.0.0 0.0.0.0 ISP1 ! it should be your preferred

ip route 0.0.0.0 0.0.0.0  2 ISP2 ! you change administrative distance

This is one way. If the ISP1 next hop is invalid then you will fall back to the second route with bigger administrative distance. this is name floating route technique.

If you can define more than a simple static route i would suggest a routing policy with route-map.

You can just change the metric or the next hop value .

Another one instead could be using the longest match. So for example:

ip route 1.0.0.0 255.0.0.0 ISP1

ip route 2.2.2.0 255.255.255.0 ISP1

ip route 1.1.1.0 255.255.255.0 ISP2

ip route 2.0.0.0 255.255.255.0 ISP2

the result of this is that the part of your traffic will flow trough ISP1 (2.2.2.0/24) while the rest will flow through ISP2 (1.1.1.0/24) due to the longest match.

http://www.cisco.com/en/US/docs/ios/12_2/iproute/command/reference/1rfindp1.html

here you can find some god ideas.

Hope this helps

Alessio

[puneet_kandwal]

hi Alessio,

Thanks for the response...

Floating routes are OK for inside to outside traffic

Would like to add one thing, I have global IP pools from two different ISP's...

How would this ensure that if one of the ISP's fail the other ISP will be able to route traffic inside seamlessly..

As per my understanding there are supposedly two ways..

1. Radware linkproof

2. Running BGP between two different ISP's.

Please correct me if I am wrong..

[puneet_kandwal]

to add on that, one ISP is 4 Mbps and other is 1 Mbps..

Thanks in advance