Two ISP WAN Connection with load balance

[sam121187]

Hi,

I am sam, i newly entering into Network concepts.So,Kindly help to resolve my problem. I have Cisco C3750-24T Switch & Two ISP WAN Connection in different Bandwidth Speeds.My Question is ISP1 is Down, ISP2 Automatically want to take full load. If ISP1 Restored Full link load automatically switch over.i browsed many areas, but not get correct configuration codes.
So,Please Provide sample configuration file.

Thank you for your support.

[M. G.]

Hi, 

the easiest solution would be to configure a static default route to ISP1 and static default route to ISP2 with metric 200. In this case ISP 1 holds an active link, if it fails, ISP2 takes over. 
The traffic reroute will work only if you use directly connected link.

In case you want to track any non-directly connected failures on ISP1, you should add IP SLA. What it does is it tells the router that if something reliable (e.g. 8.8.8.8) is not reachable through ISP1 then switch to the ISP2 link.

You can check a basic example on the below link.

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

However, from what you have on your diagram, without NAT it will not work. 

[Gaurav Mahajan]

http://docwiki.cisco.com/wiki/NAT_failover_with_DUAL_ISP_on_a_router_Configuration_Example track 1 ip sla 1 reachablity ip sla 1 icmp-echo 10.0.0.1 source-ip 10.0.0.2 ip route 0.0.0.0 0.0.0.0 10.0.0.1 track 1 ip route 0.0.0.0 0.0.0.0 20.0.0.1 10 Yes, NAT would be required for internal traffic to get load balanced.