Task with two links

giedriusv · ‎10-16-2007

Hello, please help me to slove the problem with the routing cisco 3825. i.e. there are two Internet Service Providers. I am downloading data from the First ISP, but First ISP gone unaccessible, so I want that my transfer wouldn't stop and continue using my Second ISP, then after ten minutes First ISP recovered and now is accessible, so I want that the transfer continues using First ISP. I hope You understood my problem and will help me to slove it. Thank You.

thefindjack · ‎10-16-2007

If you are using static routes with BGP to your ISP's endpoint you can set up the route metric for your secondary path higher. Or you can influence the route through BGP...either is acceptable.

example

ip route 0.0.0.0 0.0.0.0 X.X.X.X

ip route 0.0.0.0 0.0.0.0 X.X.X.X 200 <----Secondary Path set with metric of 200 (means it will prefer the top route (primary) unless it is unreachable then it will default to secondary.)

or if you are using BGP you can use the weight command...

Router(config-router)#neighbor "ip address primary isp" remote-as XX

Router(config-router)#neighbor "ip address secondary isp" remote-as XX

Router(config-router)#neighbor "ip address or primary ISP" weight

This will always prefer the primary route and if it goes down the secondary will be used. This is a powerful command and will mean that the primary will ALWAYS be used for outgoing traffic. Weight is considered before all other values.

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