half duplex vs full duplex

[al lumbis_1]

I have a B2000 set at 100FD talking to a 10HD appliance (both connected to a HP2524 Switch). The only way to ensure that there are no errors showing up on the switch is to configure the B2000 as HD as well. My question I suppose is "Isn't the switch supposed to handle this type of mismatch between network devices?"

[Michael Tully]

Yes switches are supposed to handle this type
of situation. Unfortunately some switches are
dumber than others. Is your card set up as
auto-negotiate? If so this may be the way to
go. Have a look in your /etc/rc.config.d/hp....
file for your type of card. Use the 'lanadmin'
command to check the stats. If you see many
'late collisions' this will indicate that the
card is having problems. Another of telling is
the amount of traffic when using ftp.
Do the errors appear using both HD and FD?? Or
does using one type out perform the other?

[al lumbis_1]

I did that already. I went through the process of letting the B2000 auto negotiate and then forced it to 100FD and then 10HD. The latter was the only one that got rid of the errors completely.

[Johan Gjestvang]

Make sure your 100MB switch-port is set to manually 100FD
as well as your B2000 lancard.
If one of the sides still are
in autonegotioation mode, you
easily ending up in a speed/duplex missmatch situation. Autonegotiation do
not work every time.

[Darrell Allen]

Concerning the HP B2000, was the switch port also set to 100FD? You definitely will have a problem if the duplex setting doesn't match between the HP and the switch.

Darrell

[al lumbis_1]

In my reply I forgot to mention that i also did the same thing on the switch as what i did on the computers (ie going from auto to 100FD to 10HD)

[Bill Hassell]

To avoid issues with the 100 BaseT standards and hardware, always match speed and duplex on both ends and don't use autonegotiate. This rule does not apply to Gigabit networks.

[sven verhaegen]

This might give you a clear picture of the 'normal behaviour of duplex-capable interfaces'

When one would look deep into the RFC's related to duplex modes one would eventually find following 'rules' that apply on most setups :

you need to align the type of duplex setting you specify meaning wether you select to negotiate or you work in fixed mode , the reason for that is very simple

In fixed mode on both sides no issues exist as nothing needs to be negotiated
However when using autonegotiation on either side care has to be taken , this is exactly what you are talking about , it explain why switches are not able to recover all situations :

autonegotiation is a protocol that requires 2 active negotiating sides to negotiate , if either side is in fixed mode the negotiation isn't on at all meaning it will not reply on the other sides request , that will result in any number of reactions , for a HP lancard for instance it means it will speed sense the line and then drop to HD setting on that speed , a switch from different vendors could either deactivate the port , drop to 10mb , go to HD , go to FD or any other possible setting whatever the vendor decided would be most likely to happen to the other side

so this table is a good rule for port settings

client switch
====== ======

--Correct--
forced (HD/FD) forced (HD/FD)
auto auto

--Incorrect--
forced (HD/FD) auto
auto forced (HD/FD)

... this can lead to duplex mismatches

hope this helps you out