Review your favorite Linux distribution.
Go Back > Forums > Linux Forums > Linux - Networking
User Name
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.


  Search this Thread
Old 04-14-2003, 10:11 AM   #1
LQ Newbie
Registered: Oct 2002
Location: Maryland
Distribution: Red Hat
Posts: 26

Rep: Reputation: 15
strange cable modem problem

I'm experiencing a weird problem with one of my Comcast cable modem connections. After several days of running fine, it just seems to inadvertently drop for no reason. If I do a ifconfig eth0, it still shows the interface as up with the correct IP and everything but I can't reach anything outside the local network from the box. And I can't reach the box from anywhere on the outside. If I do a simple ifdown eth0 and then try to bring the interface back up (ifup eth0) or /etc/rc.d/init.d/network restart, the interface hangs while trying to receive an IP via DHCP. However, if I simply bring the interface down and reset the cable modem by unplugging it and then bringing the interface back up it retrieves the IP address and comes up fine.

What I'm wondering is what might be making it go down and how might I correct it? I'm using RedHat 8.0 and a motorola surfboard cable modem. It receives a dynamic IP from Comcast but the IP never seems to change.
Thanks a lot.
Old 04-14-2003, 09:07 PM   #2
LQ Veteran
Registered: Feb 2003
Location: Maryland
Distribution: Slackware
Posts: 7,803
Blog Entries: 1

Rep: Reputation: 418Reputation: 418Reputation: 418Reputation: 418Reputation: 418
I have exactly the same problem with Comcast. I'm running everything through a Linksys router connected to a Motorola surfboard and when that happens, my lan is fine, but I can't get outside of it. If I just release and then renew the addresses at the router, I get exactly the same IP address and DNS addresses that I had before, but now I can use the internet. Weird if you ask me. I don't think it is at all unusual to keep getting the same IP address from Comcast. I've had the same one for quite some time, even though it is assigned via DHCP. However, my router is always on, so Comcast probably doesn't have much of a chance to assign it to someone else.

At this point, I'm blaming Comcast for the connection problems since the only thing they see is my router and it doesn't change from one day to the next.
Old 04-15-2003, 07:48 AM   #3
LQ Newbie
Registered: Apr 2003
Posts: 7

Rep: Reputation: 0
I think there were some issues with a certain modem, umm 4220 I think that needs new firmware.

I'm not positive, but if you go over to
you may be able to find some help.

They don't care about routers, but don't mention it if you are running servers because all you will get then is a bunch of people telling you how you are violating the TOS/AUP. Comcast does watch the forum, but is ususally quite in the background.
Good luck.
Old 04-16-2003, 04:24 PM   #4
LQ Newbie
Registered: Aug 2002
Location: New England (USA)
Posts: 10

Rep: Reputation: 0
Question: Are you connecting the cable modem to your computer via USB (module 'CDCEther.o') or via ethernet? Do you see any pertninent messages in your syslog files?
Old 12-19-2003, 11:52 PM   #5
Registered: Apr 2003
Location: Dallas, TX
Posts: 122

Rep: Reputation: 15
I have the same problem with comcast and the moto surfboard modem. The old modem never had a problem. But this new one does. Anyone have any ideas?

Old 12-20-2003, 08:36 PM   #6
LQ Veteran
Registered: Feb 2003
Location: Maryland
Distribution: Slackware
Posts: 7,803
Blog Entries: 1

Rep: Reputation: 418Reputation: 418Reputation: 418Reputation: 418Reputation: 418
I'm still blaming Comcast. It doesn't happen nearly so often for me as it did this spring and absolutely nothing about my network has changed. I also know several other Comcast users who have the same problem from time to time and none of us have similar hardware.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cable modem problem Amuro-Ray2020 Linux - Hardware 0 06-01-2005 02:44 AM
cable modem problem usman88 Linux - Newbie 3 04-08-2005 03:39 PM
Strange cable modem problem in Debian cellular Linux - Networking 4 09-14-2004 04:59 PM
cable modem problem figadiablo Slackware 1 11-15-2002 12:31 AM
cable modem problem mrcracky Linux - Networking 0 01-02-2002 07:41 PM > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 12:50 PM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration