Lost Default Gateway

cichlid · 14-06-2004, 14:27

I'm sure (and hoping) this has been mentioned before but can't find anything. I saw this on a friends setup about a year ago and all they can tell me it's been resolved (and don't remember how/when).
Occasionally (ok, so far at least once a week) I'd come back to my computer to read my mail or something. The machine would probably be in the middle of a download or MSN would be open (rarely is it turned off). For some reason all connections are dead. Quick check for erros - none. Check IP config - yep still have an IP address. For some reason though it is impossible to ping the default gateway - effectively disabling your connection.
The only way to get it flowing again is to reboot the modem. Not such a big deal - but it shouldn't be happening.
Has anyone seen this or a solution? I haven't spoke to Tech Support yet because I don't think they'll help ("reboot the modem, see it's working now, goodbye sir" was all my friend got told a year ago) or they are unable to help - it may well be something in my set up - who knows?
Any help appreciated - mostly because I'm puzzled by it

JonathanLH · 14-06-2004, 20:16

i too get this now and then with the ntl 200 modem, it happens if i upload lots of data for about 10 seconds continuously from at least 10 different connections, the modem's upload light then goes off, and the download light flashes occasionally.
the only solution is to restart the cable modem, i imagine it happens when the modem's buffer gets full.
i also have an ntl 120 modem that does the same thing (2 lines at this address)

cichlid · 14-06-2004, 20:56

I'm gettin a bit tired of rebooting the modem (it can't be good for it). I'd like to find out what is causing it. I've only seen it on NTL and if you happen to use USB to connect the modem I've found that it needs a reboot of the PC to correct (rather than just rebooting the modem - release and renew does nothing). Seeing this on different systems and modems must mean it's not my PC.
Any of the tech guys from NTL that browse around here got any suggestions?

Chris W · 14-06-2004, 21:00

what happens if you do

ipconfig /release then
ipconfig /renew (ipconfig /renew_all for win98/me)

in a dos prompt when the connection drops? does this bring the connection back up again or does it generate an error message? if so what is it?

cichlid · 14-06-2004, 21:11

It does nothing (I'm on XP - have seen it on other XP and 2000 machines) - you can still ping your IP address but not the default gateway.
Someone once mentioned Kazza causing it but I don't put much reliance on their expertise and I don't use Kazza anyway.
If it's any help - I would notice this more at the weekend - strange but true.

Chris W · 14-06-2004, 21:19

are you using a router?

when you say it does nothing, do you mean that nothing happens or that it just brings back the same ip address with no error?

EDIT: and BTW

to the site

cichlid · 14-06-2004, 21:39

Sorry, should have given a bit more info really.
On my own (current machine) I have no router/switch - It's quite literally a crossover cable betweent the PC and modem. No firewall and (i can hear the 'WOT's from here) no antivirus software.
Literally does nothing, nadda - sits lookin at you (like its tryin real hard). End up closing the cmd window and bouncing the modem. It always comes back no problem.

PS - I have a knack of finding weird problems like this. Usually I get to the bottom of them, eventually

Matth · 14-06-2004, 21:56

Did it to me today on STB!
If you release/renew, you end up with a 169.whatever APIPA no DHCP address - only thing that works is rebooting the box.

Chris W · 14-06-2004, 21:59

when the connection drops can you acess the configuration page of the modem? (http://192.168.100.1)

if you need the username and password, they are root and root.

try it when the connection is working because it doesn't always work. Depends on the modem.

Ignition · 14-06-2004, 22:28

Losing default gateway does without fail indicate an issue with cable connection itself - if you wish give me your IP address and I'll be happy to check your return path power levels (these things are almost always return path probs) to exclude any fault at the low levels.

The other chance is that this is a DHCP fault however due to the way the leases run and are renewed by default by windows when they have run only 50% of their total length it's unlikely to be this as DHCPs usually work 100% or not at all.

In any event if you want me to check this out I'll be more than happy to - I have somewhat more access than regular technical support and can usually assist in ways that due to their access they cannot.

cichlid · 15-06-2004, 10:58

I'll PM the IP address.
Cheers.

cichlid · 16-06-2004, 10:04

Thanks for checking the return paths.
It's happened this morning again. Had a bit torrent download running overnight. When I came in this morning it had died during the night (no idea when)
Below is the text of my efforts to get it working (actually got assigned the same ip again).

C:\Documents and Settings\Administrator>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . : 81.103.24.nnn

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 81.103.24.254

C:\Documents and Settings\Administrator>ping 81.103.24.254

Pinging 81.103.24.254 with 32 bytes of data:

Request timed out.

Request timed out.

Request timed out.

Request timed out.

Ping statistics for 81.103.24.254:

Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:\Documents and Settings\Administrator>ipconfig /release

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . : 0.0.0.0

Subnet Mask . . . . . . . . . . . : 0.0.0.0

Default Gateway . . . . . . . . . :

C:\Documents and Settings\Administrator>ipconfig /renew

Windows IP Configuration

An error occurred while renewing interface Local Area Connection : unable to con

tact your DHCP server. Request has timed out.

C:\Documents and Settings\Administrator>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

Autoconfiguration IP Address. . . : 169.254.53.10

Subnet Mask . . . . . . . . . . . : 255.255.0.0

Default Gateway . . . . . . . . . :

MODEM REBOOTED HERE

C:\Documents and Settings\Administrator>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . : 192.168.100.10

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . :

C:\Documents and Settings\Administrator>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . : 81.103.24.nnn

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 81.103.24.254

C:\Documents and Settings\Administrator>

cichlid · 16-06-2004, 10:07

PPS - just also checked my expire date on the IP address. Should it not give me the address for a full 24 hours?
DHCP Server . . . . . . . . . . . : 62.254.32.21
DNS Servers . . . . . . . . . . . : 194.168.4.100
194.168.8.100
Lease Obtained. . . . . . . . . . : 16 June 2004 09:48:34
Lease Expires . . . . . . . . . . : 17 June 2004 04:16:48

Chris W · 16-06-2004, 11:33

Quote:

Originally Posted by cichlid

<snip>

next time the connection drops, unscrew the coaxial cable and leave it out for a half minute or so. While it is out you should get the ip 192.168.100.10. Then if you replace the coax, does the modem lock back onto it's signal, or does it still need the reboot?

When you lose connection, does the modem light sequence change at all?

cichlid · 16-06-2004, 11:49

I'll have to see when it next happens - far as I can tell the lights flahs away apparently normal - I'll double check next time. My try some monitoring software - anyone any suggestions?