[patmcfar8]

Here's the situation...

I'm trying to integrate 7, 10.2.2 Macs into an existing Novell Network. It's mostly over my head and the IT guy that's helping me is new to Mac and OS X. We're slowly figuring out the whole networking thing... but as we connect them we get SLOW ASS speed between the Macs, while the PC's on the same switch get good speed.

I researched a bit and found some direction about a full-duplex / half-duplex problem, but am looking for a diffinitive answer. Anybody? Any help would be MUCH appreciated.

Here's a link to some info. that I found:
http://www.ucsf.edu/its/listserv/macosx-l/0226.html

[Camelot]

It's impossible to tell if a duplex issue is the source of your problem without more information.

For a start, what mode do your Macs think they're running in? A quick peek at the Apple System Profiler will tell you.

Once you have that, you need to look at what the switch thinks it's running at. Depending on the switch, there may be LEDs on the front of the switch, or the network admin may have to log into the switch to see.

Once you have that information, you'll know whether you have a duplex issue or not.

Apple doesn't provide any(?) way of controlling the duplex of built-in NICs, instead they recommend (demand?) that you configure the switch to auto-negotiate the duplex and speed. To their credit I've never seen a Mac auto-negotiate to anything other than the best possible speed, but they should give you the ability to override this, especially in a corporate and/or network environment.

[ghporter]

This was wierd! I thought I was replying to a different thread! Oops!

[patmcfar8]

Thanks for the reply. I have no idea what the switch is set too, but I'm thinking that's the problem. My Mac says it's running full duplex, but a quick ifconfig shows this:

media: autoselect (100baseTX <half-duplex>) status: active
supported media: none autoselect 10baseT/UTP <half-duplex> 10baseT/UTP <half-duplex,hw-loopback> 10baseT/UTP <full-duplex> 10baseT/UTP <full-duplex,hw-loopback> 100baseTX <half-duplex> 100baseTX <half-duplex,hw-loopback> 100baseTX <full-duplex> 100baseTX <full-duplex,hw-loopback> 1000baseTX <full-duplex> 1000baseTX <full-duplex,hw-loopback> 1000baseTX <full-duplex,flow-control> 1000baseTX <full-duplex,flow-control,hw-loopback>

Doesn't mean a lot to me, but it looks like the autoselect is dropping my Mac to half-duplex instead of full. I'll have my IT guy look at it and check the switch to see what it's set to.

Thanks again for the response.

Quick question: My internet connection is noticably slower compared to the PCs on the network. I've always chalked it up to IE's slow speed. Once I get this duplex situation fixed, might I see a speed increase in the internet connection speed as well? Here's hoping.

[ghporter]

It indeed looks like the switch has locked you in at half duplex. This also affects your network speed, both locally and for the Internet. In half duplex your machine has to send requests then wait for replies. If it tries to send while a reply is coming through, it has to stop, wait a pseudorandom length of time, then start the send again. In full duplex it can do both functions simultaneously.

It is possible that the switch you're connected to is optimized for a certain kind of NIC, or its autodetect feature may be disabled. Either way, that's what your IT folks get paid for.

[PowerMac2001]

Originally posted by Camelot:
Apple doesn't provide any(?) way of controlling the duplex of built-in NICs, instead they recommend (demand?) that you configure the switch to auto-negotiate the duplex and speed. To their credit I've never seen a Mac auto-negotiate to anything other than the best possible speed, but they should give you the ability to override this, especially in a corporate and/or network environment.

Thats incorrect. Apple does support changing the media options config and I've done it lots of times. Just go in via the terminal and enter something like ifconfig en0 media 100baseTX mediaopt full-duplex

[PowerMac2001]

Originally posted by patmcfar8:
Thanks for the reply. I have no idea what the switch is set too, but I'm thinking that's the problem. My Mac says it's running full duplex, but a quick ifconfig shows this:

media: autoselect (100baseTX <half-duplex>) status: active

Are you saying that in ASP its reporting that you're running full-duplex? Are the PC's connected at half or full to the same switch. Try forcing the media opts to full-duplex and make sure that it is a switch not a hub that you're connected to.

[tooki]

Incorrect auto-negotiation with certain *cough*Cisco!*cough switches is a common problem. Also significant are the problems with switches that incorrectly have spanning-tree protocol active on all ports (although this has different symptoms from what you describe).

See what happens if you force different duplex modes, and see if you benefit at all from placing all the macs on a small, unmanaged switch, and connecting that to the real switch.

tooki