Machines won't link any higher than 10 Mb - half duplex

[JWalker55]

I'm an IT admin at a small business, with about an 8 machine network. Networking is not exactly my main area, which is why i'm reaching out here. The basic issue is that most of the machines will not link any faster than 10 Mb, half duplex. They are setup with static IP's. One machine will link at 10 Mb full, and work fine, but if I try 10 Mb full on the others, it'll work, but very slowly. These machines will not work at all at 100 Mb full or half. I can't get a ping response from anything.

Two of the machines (both Dell's w/P4, 512MB, XP Pro) have an integrated Broadcom 440x 10/100 controller, and one other machine has both a generic PCI adapter (can't remember brand/model off hand), and an intel integrated 10/100 controller. Neither will work at 100 Mb full or half just like the Broadcom. One new Dell machine will link at 100 Mb full, but is very slow (slower than at 10 Mb half). Our Poweredge server links at 100 Mb full with no issues, as do 3 laptops (did file transfer tests across the network). Aside from the PCs, the only thing connected to the network is a print server, wireless AP, and DSL modem. Everything is connected to a D-Link 16 port switch. I just swapped out our older Dell 16 port switch for the cheap D-Link to see if it were a compatibility issue there, but obviously not. Tried the laptops on all of the same ethernet jacks as the desktop machines and all work fine, so I would not suspect any issues with cables/wiring in the building. Tried disconnecting everything, and connecting only 2 devices at a time in a ton of combinations and no go there either. Updated drivers on all the NICS. The only thing that keeps me hesitant on replacing the NICS right away is that the problem exists across multiple chipsets.

Unfortunately, I wasn't working here when this was all setup originally. I contacted the person who did set everything up and he thought it was a compatibility issue between the NICS and the switch, but that doesn't seem likely since the issue persists with both switches. Any ideas? I've got a PCI NIC laying around at home that i'm going to bring in and try in one of the machines.

 

[Crusty]

unless you can specify the port speed/duplex on the switch itself you should be using auto-negotiate for all the devices. setting them manually will only cause you more problems. if they are already set on auto-negotiate then it sounds like a cabling problem. make sure all patch cables are factory made and replace any cables with visible tears/cuts in the shielding.

 

[spidey07]

That screams of bad cabling. What model of switch is it? It's possible that the cabling in the wall is not category5 or higher which is required for 100 Base-T. Or even more possible that the cabling isn't installed correctly and isn't category anything.

You should be able to read the jacket of the cable where it terminates into a patch panel near the equipment room/switch.

 

[JWalker55]

It's all cat5 cable. If I set all the NICS to auto-negotiate then they will link at 100 Mb full but cannot get any activity out of them, no ping response from anything. Setting the speed manually is the only way they will work. This is the way they were setup years ago, before I got here. If I revert to DHCP, they will not grab an IP from the DHCP server.

 

[spidey07]

Ok, so you do get physical link when set to auto. But then you can't move any data over it? And when you force it to 10/half you can communicate, if you force to 10/full you can communicate, but slowly?

If so then I can say with absolute certainty that you have a cabling problem. You're probably going to have to hire a cable installer to come out, certify and repair your cabling. With only 8 machines it will probably cost around 1000 bucks and is worth every penny.

 

[ScottMac]

Originally posted by: spidey07
Ok, so you do get physical link when set to auto. But then you can't move any data over it? And when you force it to 10/half you can communicate, if you force to 10/full you can communicate, but slowly?

If so then I can say with absolute certainty that you have a cabling problem. You're probably going to have to hire a cable installer to come out, certify and repair your cabling. With only 8 machines it will probably cost around 1000 bucks and is worth every penny.

I agree.

Check the cables to make sure they were terminated using 568A or 568b standards.
(either Green-white, Green, Orange-white, Blue, Blue-white, Orange, Brown-white, Brown,

or
Orange-white, Orange, Green-white, Blue, Blue-white, Green, Brown-white, Brown, as viewed from the top of the connector / clip away from you, left-to-right)

It could even be poorly handmade jumpers from the pcs to the wall jack.

This specific symptom is associated with a "split pair, 3&6" ... meaning that the wire connected to pin 3 is from a different color pair than the wire connected to pin 6. The result is SEVERE cross-talk, which interferes with full duplex specifically, and higher speeds secondarily.

Pins 3&6 (which is "pair 2") are one of the pairs used for Ethernet & Fast Ethernet. Gig Ethernet uses all four pair to transmit and receive, both directions, at the same time (all four pair transmit and receive at the same time, both directions, concurrently).

 

[Slowlearner]

You can check this very easily, by connecting two pc/laptops directly to the switch using store bought/newegg/monoprice cables and then checking the speed at which they connect.

 

[JWalker55]

I suspected cable also. The 3 notebooks I tested pulled 75+ Mb/s no problem on the same cabling though. I guess certain chipsets are more sensitive?

If it comes down to it, I doubt my boss (the owner) will want to spend any money on it, since it really isn't causing any issues that he would care about (lol). More of an annoyance on my end, and since i'm really the only one moving any remotely large files across the network.

 

[Bashbelly]

damn if money is an issue just run some new premade cat5e cables (you can get some pretty long ones), and hide them with some inexpensive raceway. Easily under $100 for everything.

 

[ScottMac]

Except they would be stranded conductors (being pre-made jumpers) which are much higher loss and, more importantly, out of spec for that aspect of the application.

This is a business, it shouldn't be jury-rigged.