Connectivity/Modem issues

neilpike · 28-04-2007, 21:30

NTL/Ambit 200 modem, VM 10Mbit/sec service in Cambridge (ex-NTL, ex-Cambridge Cable service).

I've been getting disconnected several times a day starting on Thursday - everything fine until then.

Symptoms :-
(1) No internet connection. I can't even ping the default gateway
(2) No response on http://192.168.100.1 (indicating some sort of modem issue)
(3) Modem not contactable by VM tech support
(4) If I release/renew my host IP address I don't get a new one - I get a 169.x.x.x IPIPA one.

Fix :-
Reboot cable modem (every few hours....)

Other Info :-
(1) The cable modem IS passing some traffic. If I do a sniffer trace on it's ethernet interface I do see traffic from other devices out in the network - e.g. bootp/dhcp requests from other nodes in my area, devices trying to connect to my IP (tcp scans and the like) So the modem isn't completely dead, just not passing any of my traffic out.

After several calls to VM tech support they've eventually agreed to send an engineer. Support has always been friendly, if not the most technical - I almost laughed out loud at their attempt to explain why I should set my nic setting to 10/half duplex. But I bit my tongue. Every time you call the first thing they ask you to do is reboot the modem, which "resolves" the issue, but they can't/won't do anything until you've done that....

There's only one device/IP attached to the cable modem - normally a PIX firewall, but for the purposes of calling VM tech support I just put a single pc on it so as not to confuse the matter (and prove it was nothing to do with the PIX - which it wasn't).

I've seen a few other recent posts with similar looking issues, so the info above may be of help/interest.

Hopefully the engineer will bring another cable modem with them and swap it out. Any recommendations, assuming they have more than one model with them? (Before this one I had a Terayon, which died completely after 18months service).

Sirpingalot · 29-04-2007, 15:14

I'm not too sure, but there's clearly something wrong with the modem. I don't think they can accept responsibility once you've explained there's another device attached (PIX-I assume it's an attacable device of some sort?).

Perhaps somebody else can help diagnose the problem.

Druchii · 29-04-2007, 16:10

A VM 255, or an Amnbit 250, or the Surfboard 5101E. All great modems, listed newest to oldest here

Sirpingalot · 29-04-2007, 16:13

Sarcasm much?

neilpike · 29-04-2007, 17:03

Quote:

Originally Posted by Sirpingalot

I'm not too sure, but there's clearly something wrong with the modem. I don't think they can accept responsibility once you've explained there's another device attached (PIX-I assume it's an attacable device of some sort?).

Perhaps somebody else can help diagnose the problem.

A PIX is a Cisco hardware firewall.

---------- Post added at 18:03 ---------- Previous post was at 18:01 ----------

Quote:

Originally Posted by Druchii

A VM 255, or an Amnbit 250, or the Surfboard 5101E. All great modems, listed newest to oldest here

Thanks Druchii - fingers crossed they have one of these with them....

Keithyboy · 30-04-2007, 23:20

Neilpike - where does the 192.168.100.1 address that you mentioned come from? Both myself and my neighbour had an issue recently where the modems were picking up 192.168.100.... addresses with a 30 second lease time, which basically meant that they were unusable due to them constantly trying to renew (and being internal addresses). This was with a direct connection from the modem to the pc.