Transmitting but Not Receiving Packets on NIC

[zevzeg]

Trying to get a friend's PC working with Comcast high speed internet at
home via cable modem. Having some strange software issue with the PC.

I installed a known, working NetGear NIC and related drivers in the
Gateway PC that is running Windows XP SP1. (I had to install this NIC
because the onboard Intel NIC with latest drivers was "flapping" -
would continuously go between "enabled" and "disconnected" states).

Windows shows the status of the NetGear LAN Connection as "Enabled" and
the link light LED is green and showing activity. However, the NIC
statistics show that packets are being transmitted but "0" packets are
being received. I had Ethereal running on the PC and it shows the DHCP
Discover packets being transmitted (reflected in statistics) and other
DHCP broadcasts for other MAC addresses.

I plugged 2 other PCs into the cable modem and both obtained IP
addresses right away. Therefore I know that Comcast service is working
properly and providing addresses via DHCP.

I know this is strange but my guess is that there is some software that
is installed on the PC that is preventing packets from being received
by the NIC. I tried uninstalling AOL, Norton AV, and Spy Sweeper
software and still saw the problem. I also tried enabling/disabling
the windows firewall.

At this point I've run out of ideas and asking for help from anyone out
there that has seen this problem before or may have other ideas.

Thanks,
Z

 

[John Wunderlich]

(e-mail address removed) wrote in

Trying to get a friend's PC working with Comcast high speed
internet at home via cable modem. Having some strange software
issue with the PC.

I installed a known, working NetGear NIC and related drivers in
the Gateway PC that is running Windows XP SP1. (I had to install
this NIC because the onboard Intel NIC with latest drivers was
"flapping" - would continuously go between "enabled" and
"disconnected" states).

Windows shows the status of the NetGear LAN Connection as
"Enabled" and the link light LED is green and showing activity.
However, the NIC statistics show that packets are being
transmitted but "0" packets are being received. I had Ethereal
running on the PC and it shows the DHCP Discover packets being
transmitted (reflected in statistics) and other DHCP broadcasts
for other MAC addresses.

I plugged 2 other PCs into the cable modem and both obtained IP
addresses right away. Therefore I know that Comcast service is
working properly and providing addresses via DHCP.

I know this is strange but my guess is that there is some software
that is installed on the PC that is preventing packets from being
received by the NIC. I tried uninstalling AOL, Norton AV, and Spy
Sweeper software and still saw the problem. I also tried
enabling/disabling the windows firewall.

At this point I've run out of ideas and asking for help from
anyone out there that has seen this problem before or may have
other ideas.

Thanks,
Z

When you plugged the other computers into the cable modem, did you
use the same cable? This sounds like it might be a bad cable.

-- John

 

[zevzeg]

Yes, I used the same cable. So I know the cable is good.

 

[John Wunderlich]

Yes, I used the same cable. So I know the cable is good.

At this point, I'm out of clues. As a despiration measure, you might
try the LSP fix program. Check out the following website and see if
this tool might fix your problem... (couldn't hurt)...

<http://cexx.org/lspfix.htm>

HTH,
John

 

[zevzeg]

Just an update on this issue. I put a hub in-line between the PC and
cable modem. Then using a second PC I was able to use Ethereal to take
a packet capture. What I found was that Comcast was not sending a DHCP
Offer in response to the PC's DHCP Discover. Previously I had assumed
that Comcast was sending this since my laptop worked when I plugged it
in. Therefore the problem was with Comcast's network and not the PC.

Anyways, the solution to the problem was simple. Comcast remotely
reset the cable modem and subsequently the DHCP exchange worked
normally. Wish I had thought of this previously but I was too focused
on the PC. Thanks to John for his help.

Thanks,
Z

 

[John Wunderlich]

(e-mail address removed) wrote in

Just an update on this issue. I put a hub in-line between the PC
and cable modem. Then using a second PC I was able to use
Ethereal to take a packet capture. What I found was that Comcast
was not sending a DHCP Offer in response to the PC's DHCP
Discover. Previously I had assumed that Comcast was sending this
since my laptop worked when I plugged it in. Therefore the
problem was with Comcast's network and not the PC.

Anyways, the solution to the problem was simple. Comcast remotely
reset the cable modem and subsequently the DHCP exchange worked
normally. Wish I had thought of this previously but I was too
focused on the PC. Thanks to John for his help.

Thanks,
Z

Thanks for closing the loop
I'm glad you're working again

-- John