How does this qualify as a hint ?

PS I have panther and I don't have any issues with link negotiation. This should be in the forums not here.

I agree that this seems rather basic, but some people may not be aware that Panther doesn't always set the network settings right. Chill out for a minute and lay off the coffee for a while. :-D

I agree. Helping people is worth it; the benefit outweighs the minor inconvenience you experience when you see a hint you know you don't need.

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osxpounder

This really doesn't have anything to do with Panther in particular. As someone who built large-ish Ethernet networks in a past life, I can certainly vouch for the fact that auto-negotiation isn't always automatic.

It's a simple case of certain hardware not talking well to certain other hardware. Certain NICs don't like certain switches, certain switches don't like certain other switches, etc.

While having the wrong speed or duplex settings can drastically hurt performance, I've never seen any damage done by messing with them. Generally, switches run full duplex, hubs run at half, although it's not always the case. Most mismatch issues are with duplex negotiation, not speed.

To all who think this is not a valid hint: why do you think Apple included to possibility to choose your network speed, if it's useless ?

Doing this is an incredibly bad idea. Setting the interface to the wrong settings manually can create nasty performance problems.

The speed detection is all done by HW anyway, not any of Apple's SW, so it is unlikely that you would ever have a reason to change these settings.

Doesn't always work. My old Lombard PowerBook had problems with certain 100mb/s hubs and routers, for example, and under System 9.0 I had to use the speed and duplex software to force the PowerBook into 10mb/s mode. When I moved to Mac OS X 10.0, I couldn't do that anymore, so just carried a 10mb/s only hub with me everywhere, which always negotiated fine.



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--Jim (me)

So to make this a useful hint....
How does one check if you are connected at 10 or 100 or 1000 and whether the connection is half or full duplex?

ifconfig en0

You are correct in that NWAY is handled by the hardware. But NWAY is not bulletproof, and if you know and understand your LAN topology, setting the proper intf params manually is a reasonable solution..

I agree that this is a very limp "hint".

And unfortunately we see far too many of them here; I guess Rob's just posting them to pump the site traffic as hard as he can. I would prefer it though if he concentrated on quality rather than quantity.

I suspect any "hint" one doesn't find useful is "limp." I don't know about this particular hint, but I sometimes find help in strange places, so I wouldn't want to discourage anyone. After all, we aren't all as advanced as some sound.

I'm actually big on this hint, and here's why:

I just got my new alBook 15" this past Wednesday, and just in time for an event I was supposed to webcast. I get to the venue and the sysadmin hands me the ethernet cable, tells me all about the DSL line, etc.

Turns out he'd strung a 200-foot cable from his networking closet into a back room, then attached a cheapo connector for ANOTHER 100 foot cable which then came into the press booth where I was.

He'd assigned me a specific static IP behind their DSL router's firewall, but whenever I tried manually assigning the address to my machine, it'd kernel panic. This happened multiple times.

Manually forcing the speed down to 10/100 prevented this from happening... but I wish I'd known about the existence of this feature a little sooner!

If you have to change the connection speed its not a problem with Panther or MacOS, the problem is with your cables. If your cables are bad in some way (not all the wires are connected or are in the wrong order) this will happen.

Before blaming MacOS, check your cables.

Actually this is usually an issue with spanning tree. Or more specifically portfast (the cisco term other vendoors call it other things) not being turned on. http://docs.info.apple.com/article.html?artnum=30922 talks a little about it from the appletalk perspective, but is also a problem with link negotiation.

Basically the problem is that the switch port is not enabled until a check for a network loop is finished. On a modern fast computer auto-negotiation has finished before the link is actually enabled. Some clueless administrators then set the port to a fixed rate and then auto-negotiation is guaranteed to fail although as long as the host is set for the right settings things work fine. The correct thing to do is to set the port to turn on immmediately and only turn off if a loop is detected. Turning the port on first is the so called portfast feature. All of that is of course a gross simplification. If you want to know more do a search on spanning tree/802.1d/Portfast etc.

I will insert my comment here and leav it to you all to tag off it. I have a problem where my DEC based 10/100 card is only beign detected as a 10baseT card.

This ONLY started with Panther and it stops when I revert to X.2. This is not to disparage anyone but it can be so hard to find the answer and I think you are all right (in the proper situation). If it works in 9 and X.2 but does not in X.3 then it is not a cable. Apple did update the DEC kext and it is not backward compatible.

It is a Asante 10/100 card and when I try to use ifconfig to change ANY parameters it tells me OPERATION NOT PERMITTED.

--:~ --$ ifconfig en1
en1: flags=8863 mtu 1500
inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255
ether 00:00:94:a4:3e:fd
media: autoselect (10baseT/UTP) status: active
supported media: 10baseT/UTP 100baseTX 10baseT/UTP 100baseTX autoselect autoselect 10baseT/UTP
--:~ --$ ifconfig en1 media 100baseTX
ifconfig: SIOCSIFMEDIA: Operation not permitted
--:~ --$ ifconfig en1 media 100baseTX mediaopt full-duplex
ifconfig: SIOCSIFMEDIA: Operation not permitted
--:~ --$ ifconfig en1 media 100baseTX full-duplex
ifconfig: SIOCSIFMEDIA: Operation not permitted
--:~ --$

same thing as root (JIK) an I have tried to FORCE it within NETWORK in SYSTEM PREFERENCES but no luck. As an adendum, I can see in my system.log that the card is announcing (at statup) that 10baseT LINK OK but nothing after that (100baseTX LINK OK etc). I do have ONE, ONE lone start at which (apparently) it shows 100baseTX LINK OK but that is out of about 50-100 restarts.

This is definitely a hint. I had the same problem once with a ti portable to connect with a hub. I isolated the problem to an incapacity of the card to select the right speed to talk to the ethernet hub (it could take up to 45 minutes until something happened). As soon as I selected manually a speed for the card, everything went well.

This is a valid hint, at work we have a Cisco based network (ATM) and it doesnt like the AUTO/AUTO (speed/duplex) setting. You need to know your port speed and make sure the NIC settings match otherwise you will have many transmit and receive errors. If the port is set to auto auto then it is anybodys guess as to what the two NIC's will negotiate. I suggest unless the network port, switch, router or hub is hard coded to a specific speed and duplex, leave the default setting unchanged. If the LAN/WAN side is hard coded set the Mac's NIC to match that setting.

E

I realize that this is a fairly simple hint, but I couldn't figure out why my old iMac could connect to my network just fine with automatic speed detection, while my friend's newer PowerBook couldn't. I didn't realize that the incorrectly setting the speed would prevent a network connection entirely.

One feature of Windows XP that I wish was on Mac OS X is that when a network connection is fount, it pops up a notification and tells you the speed. I didn't know the connection speed of my network at the time, as some changes were being made to it by the powers that be, thus the trial and error bit.

This can a useful hint, but only when you know a little more background about networking. So here is that background:

All ethernet cables have 4 pairs of copper wire, 8 wires total. 10 and 100Mbps ethernet uses 2 of those 4 pairs to transmit and recieve information. 1000Mbps (GigE) uses all 4 pairs.

Most computers (Mac or PC, any OS) figure out how fast the ethernet connection is automatically.

If you connected at 1000Mbps your computer will try to send and recieve data on all 4 pairs of wires. If you have a bad network cable or jack (a common problem) and are connected at 1000Mbps the connection will fail. When you set your network connection manually to 10 or 100Mbps your computer will only try to send and recieve data over 2 pair of wires. If those pairs work, everything will work fine at the slower speed.

Thus, setting your network connection manually to a slower speed is a temporary solution until you can fix the physical problem--usually in the patch cable from network jack to computer. You are, however, cutting your performance by a factor of 10.

To see your network connection speed, open the terminal and enter the line: ifconfig en0

To change your speed manually, do as "rgovostes " said, or do it via command line. Check the ifconfig man page for how to do that.

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-Mort