I have a Gigabit card in a compaq server that is set to auto (negotiation ), Its connected to a port that is set to 100M Full Duplex, and yes I realise that this is not a good idea.
The Gigabit card connects at 100M full duplex.
My understanding of the auto-negotiate process is that if one end has fixed 100M and full duplex, the auto end will cease the normal auto process pick up the 100M idle pulses and then switch to half-duplex.
So why does my server card switch to 100M full ?
Stuart.
What was the problem again?
In article , wrote: : snipped-for-privacy@nospam.please (Stuart Robinson) wrote: :>connected to a port that is set to 100M Full Duplex
:>The Gigabit card connects at 100M full duplex.
:>So why does my server card switch to 100M full ?
:What was the problem again?
Stuart is expecting the negotation to fail to detect that the remote end is Full Duplex, and is wondering how, when the remote end is [supposedly] not sending any configuration pulses, that the local end is able to figure out the duplex anyhow.
Are you _quite_ sure that the GbE NIC is strapped to auto?
That is my understanding as well. I suppose GbE autoneg may have been "extended" in some way but still...
Luck perhaps? It does not sound like a situation upon which one should rely.
rick jones
Some devices will continue to send out autonegiation FLPs even if the port is configured with a fixed speed and duplex. It will just advertise only those fixed settings.
As Walter said, why does the card decide on FULL duplex ?
Stuart.
Yes, its a defined by a load line on a Netware server autoexec.ncf, although I suppose the driver could have a bug and is ignoring the auto command.
My thoughts too, I guess the person who decided that the card should be on auto tried it, found it worked and assumed it was therefore correct.
Stuart.
Really ?
That is interesting and would explain why it goes to 100Full, the switch in question is one of the Cisco Catalyst jobs.
Is this part of the standard and do some manufacturers do it 'just in case'.
Stuart.
I believe that the 2950 will do this. I can't remember if its considered a bug or a feature. I did a quick search of the cisco web site but couldn't find anything one way or the other.
This is perfectly acceptable behavior. It is neither required, nor prohibited by the standards, however, it is the *preferred* method of limiting device configuration in that it allows the type of scenario you describe (negotiating to 100 Mb/s FDX with a 10/100/1000 card).
By the way, it should NOT be possible to disable Auto-Negotiation for a
1000BASE-T-capable interface. A-N is used in 1000BASE-T for much more than determining speed and duplexity; various other operational parameters are negotiated, including selection of the clock master for the link. A-N is not optional for 1000BASE-T.
-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX
Send replies to: usenet at richseifert dot com
I understand that there is only Auto for the 1000BASE-T side, but are you saying it should not be possible (via a driver setting) to fix a a 1000 BASE-T capable card to 100Mfull, 100Mhalf etc ?
Stuart.
Of course, you may be able to configure a 1000BASE-T capable card to not use that capability, either by advertising only lower capabilities, or by a fixed configuration at 10 or 100 Mb/s. What it is NOT possible to do is to create a fixed (i.e., non-negotiated) 1000BASE-T configuration, since negotiation is required to achieve such operation.
-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX
Send replies to: usenet at richseifert dot com
IOW if one ONLY wants to see 10BASET protocol from a 10/100/100BASET capable interface the PHY must only advertise 10BASET? Same with 100BASET?
Thanks in advance.
The PHY can either advertise that capability (using Auto-Negotiation), or forgo Auto-Negotiation altogether and just apply the desired
10/100BASE-T signaling. An Auto-Negotiating device at the other end of the link will parallel detect the signaling and configure itself to that mode of operation (assuming that it is capable of doing so).-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX
Send replies to: usenet at richseifert dot com
Nice try... We have encountered some older Broadcom chip sets plus Cisco 2930 who do require a bit of fig'in to get 1000Base-T configuration to work by the use of Manual Configuration.
A bloody pain here for while (until the next HW rev.)
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