Most puzzling networking problem I've seen

cianclarke

Have a Dell Vostro with Vista Home Basic with a built-in NIC, which recently stopped picking up when a cable was plugged in.
I installed a new NIC which I had just bought, same problem.

The only way to fix the "cable unplugged" problem was to switch to 10mb half duplex mode!! By doing this I've been trying with both NIC's to get connection.
On each, I get connection but with no IP coming through DHCP.
Then, I assign an IP within the range given by the router static. Still limited - packets sent, but not received.

The connection works fine plugging the cable into two other laptops, it's just the desktop - and the router is fine too, although I have tried two.

I've also tried disabling IPv6 and every other protocol other than IPv4 to no avail. At this point I'm thinking re-install this ****ty ****ty OS, but unfortunately Big Red Book is installed on this PC, and to reinstall you need to call them up and get some sort of unlock code, which they charge you for - so that's a seriously last resort.

Anybody got any ideas?

azzeretti

Strange one alright. What I might do is to convert it to a virtual machine and see how it runs on one of the other laptops. This will server two purposes, it will rule out a problem with the hardware/OS and also save your Red Book app. If it turns out its an OS problem, you could wipe the original and then install the original OS and install VMWare/Virtual PC and add the image as a virtual machine. This way you should, because of the same Hardware hash, still have a valid OS with Red Book as well as a good working Host OS.

If, though, you aren't concerned with the app, I would start again, it does sound like an OS issues, rather than hardware. Is it brand new? Any changes lately? Could you Sys Restore to check etc?

Jonathan

Are they on the same workgoup/domain?

Alun

I assume you've tried different cables, and different ports on the router as well. How long is the cable you're using? Particularly if it's a long cable, is it wired correctly (you'd be surprised how many aren't). Long cables with split pairs (see http://en.wikipedia.org/wiki/Split_pair) can cause all kinds of weird and unexplainable behaviour.

ressem

I'd think that it's a problem with the network cable also.

With those Dell desktops there is a Broadcom or Intel application which you can use to test the cable back to the router's switch, and it'll tell you whether there are open pairs or crossed wires.

The Vostro has a gigabit card, the laptops are possibly 10/100 Mbit?

Gigabit does autonegotiation by default and uses 8 wires, 100Mbit uses 4.

azzeretti

To be honest, if you read the OP's post it couldn't, or shouldn't be the cable or the NIC.

Have a Dell Vostro with Vista Home Basic with a built-in NIC, which recently stopped picking up when a cable was plugged in.

This implies the cable and the PC did, at one stage work.

I installed a new NIC which I had just bought, same problem.

Kinds points to something common, something like OS, Motherboard or maybe cable, which has been ruled out as it did work.

On each, I get connection but with no IP coming through DHCP.

Anytime I have seen this its been OS related, usually some app stopping broadcasts. Symantec's TeeFer2 driver is a prime example of this.

Packets sent, not recevied

umm, packets being restricted because of Layer 1 problem?......

I would be only looking at software or common hardware problems at this stage. Just as a matter of interest, what router are you using? Is there a switch in between?

Gigabit does auto negotiation by default

By what default? Driver specific? Hardware Specific? OS Specific? GB transfers ONLY use Auto Negotiate at layer 1 to advertise its preferred connectivity.

Capt'n Midnight

firewall ?
try again in safe mode with network support

make sure pc is patched up to date in 10/100 mode too

ressem

Sorry, I did read the OP. But one of the computers that I deal with about 2 months ago had exactly the same symptoms and replacing the cable did solve the issue.

And testing using the supplied Broadcom software is a simple zero cost test, seeing as the OP has not mentioned replacing the cable.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00800a7af0.shtml

Gigabit Autonegotiation (No Link to Connected Device)

Gigabit Ethernet has an autonegotiation procedure that is more extensive than what is used for 10/100 Mbps Ethernet (Gigabit autonegotiation specification IEEE 802.3z-1998). The Gigabit autonegotiation negotiates flow control, duplex mode, and remote fault information. You must either enable or disable link negotiation on both ends of the link. Both ends of the link must be set to the same value or the link does not connect.

If either device does not support Gigabit autonegotiation, disable Gigabit autonegotiation in order to force the link up.

In my case, the single open pair disrupted autonegotiation in some manner.

Cables can get damaged. And the new NIC is also likely to be Gigabit capable.

I would agree that when it malfunctions, Symantec's security software can cause issues with getting an ip from DHCP, and needed to be removed using one of the removal tools on the Symantec site.

Alun

azzeretti wrote: »

umm, packets being restricted because of Layer 1 problem?......

Well, not 'restricted' but frames being sent but received with say CRC errors, and therefore discarded can certainly be down to a layer 1 problem.

Cables can suddenly go bad as well, for example if a PC is pushed tight up against a wall, and there's unnecessary strain put on where the cable goes into the connector, or a badly crimped cable with a marginal connection on one of the pins. Seen it many times. Even with things like split pairs, I've seen cables work for ages seemingly OK, but then just stop working, maybe because there's a new source of interference appeared that wasn't there before.

azzeretti

Alun wrote: »

Well, not 'restricted' but frames being sent but received with say CRC errors, and therefore discarded can certainly be down to a layer 1 problem.

Cables can suddenly go bad as well, for example if a PC is pushed tight up against a wall, and there's unnecessary strain put on where the cable goes into the connector, or a badly crimped cable with a marginal connection on one of the pins. Seen it many times. Even with things like split pairs, I've seen cables work for ages seemingly OK, but then just stop working, maybe because there's a new source of interference appeared that wasn't there before.

I was referring to the DHCP request being a packet, that's where the error is. It doesn't care about anything that happens before or after, as I am as sure you know.
Also, if its the cable, how would switching to half duplex and 10Mb change anything..........I think we could go on for a while on this.....The cheapest and easiest thing to do is change the cable.......then try the rest I suppose.

Alun

azzeretti wrote: »

The cheapest and easiest thing to do is change the cable.......then try the rest I suppose.

Exactly. When the standard "pattern matching" approach (trying to match observed symptoms with common faults) breaks down then the only way forward is to systematically work up the OSI layers, from the bottom up in my experience.

stevire

cianclarke wrote: »

Have a Dell Vostro with Vista Home Basic with a built-in NIC, which recently stopped picking up when a cable was plugged in.
I installed a new NIC which I had just bought, same problem.

The only way to fix the "cable unplugged" problem was to switch to 10mb half duplex mode!! By doing this I've been trying with both NIC's to get connection.
On each, I get connection but with no IP coming through DHCP.
Then, I assign an IP within the range given by the router static. Still limited - packets sent, but not received.

The connection works fine plugging the cable into two other laptops, it's just the desktop - and the router is fine too, although I have tried two.

I've also tried disabling IPv6 and every other protocol other than IPv4 to no avail. At this point I'm thinking re-install this ****ty ****ty OS, but unfortunately Big Red Book is installed on this PC, and to reinstall you need to call them up and get some sort of unlock code, which they charge you for - so that's a seriously last resort.

Anybody got any ideas?

I had the exact same problem with one of the computers in the house. Tried assigning IPs all that crap and nothing worked. In the end it turned out to be a router problem, a quick upgrade of the firmware and everything was sorted. It's no harm updating your firmware either way and its worth a try...
Also, simple mistake but make sure the max amount of connections to the router is set to or higher than the number of computers connecting.