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Changing ASA5505 Config to use a Different ISP

John_at_Grid
Level 1
Level 1

We have had an ASA5505 for close to two years. About a year ago, we added a second ISP ("BOB") which became our primary and our old one (SBC) became our backup. I successfully modified the config for this and it's been working well.

Now we're changing our primary ISP to Comcast and getting rid of BOB, so right now we actually have 3 ISPs coming into our building.

I removed the BOB interface and routes, then added an interface for Comcast using an IP address from the range they provided as well as a static route to the gateway they provided - everything is analagous to the previous interfaces and routes, but it doesn't work. If I physically disconnect the Ethernet cable going to the Comcast cable modem, then the ASA does fail back to the SBC interface as expected. If I put the BOB interface & route back in there, it works again through BOB.

If I connect a PC to the Comcast cable modem and use an IP/Gateway they provided, the Internet connection *does* work. Using this same exact IP info in the ASA doesn't work.

Is there some other configuration item besides interfaces and static routes that I should be modifying? Is there some way I can dig deeper into the ASA to see exactly what is failing?

Thanks!

John

2 Replies 2

John Blakley
VIP Alumni
VIP Alumni

It's hard to say without seeing your config. Generally, you'll just change the interface address and the static route that points to them. There are a couple of things that you can do. Can you ping Comcast from the ASA when the connection is made? What doesn't "work?"

HTH, John *** Please rate all useful posts ***

John_at_Grid
Level 1
Level 1

Found the solution - a dynamic NAT rule was needed in the firewall settings.

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