Cisco ASA 5505 connected to DSL modem bridge mode
Posted on 2014-09-07
This is a weird one. One of my clients has switched from a wireless ISP to a new DSL ISP to the area. I went out to the site, got the ISP on the phone, and he changed it the modem over to bridge mode. I logged into the ASA 5505 and changed the public static IP on Vlan2 from the old public IP/SM of the previous ISP to the new public IP/SM of the new ISP. I also changed the default route.
I confirmed I could ping out to 18.104.22.168 from the firewall and also from my laptop that was connected to one of the ethernet ports of the firewall (Vlan1). I also verified I could get to Google and a couple other sites from a web browser and I verified from a couple of the client computers too. I hung up with the ISP since all was good. About 10-15 seconds later, the Internet dropped and never came back. I tried the standard procedures -- reboot the modem, reboot the firewall, etc. None of it worked. I decided to plug my laptop in directly to the modem, set the public IP, and I was able to access the Internet with no problems.
I got ISP on the phone and they said they could see the modem and everything was good. They did stress tests and things and everything was clean according to them. I tried different things I could think of - changing duplex & speed settings on E0/0, clear xlate, clear arp, looking through logs in buffer, but nothing would work. The internet would work and stop working with the DSL to firewall. Mostly it didn't work and when it did work it was for a few seconds to a few minutes and then dead for a long time after that.
I checked all the cables and I even unplugged all machines from the network and still no luck.
Finally I took the modem to the ISP to swap with a brand new one. We went through the same song and dance of configuring it in bridge mode and we got the exact same results.
I had a brand new spare ASA 5505 in my truck and slapped the config on that and the same thing happened.
They had an old Linksys sitting there that I wanted to try a static IP on but they were wrapping it up there and needed me to head on out before I could try it.
Anyone know of any compatibility problems between Cisco ASA 5505 & Visionnet M405 Rev3? If so, what's a solid compatible DSL modem I should get the client to purchase instead?
I can post the ASA config if you think that will help.
NOTE: DHCP on their DSL works like a champ.