I want to set up our Cisco 3640 router for two default gateways, one sending traffic over our T1 line, and another gateway onto a 256K circuit in the advent of T1 failure. What is the easiest way to accomplish this? Thank you for any help.
Re: How can I set two default gateways on 3640 router
The easiest way is probably a floating static route. You can search the site to get the details, but basically you'll have two default routes -- one out each interface. You'll give the one pointing out the 256K circuit a higher administrative distance so that the T1 route is more preferable -- the 256K circuit route will therefore only be used when the T1 interface is down.
The catch here is that the T1 interface has to change state (from "up" to "down") for the router to remove the T1 route and therefore use the 256K circuit route. Usually the interface does indeed change state when a leased line goes down, but it is sometimes the case that the circuit can't pass traffic but is still "up" from the router's standpoint. Failing over to another route when such an outage occurs requires the use of a routing protocol (unless anyone else has an alternative -- I can't think of one).
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