Speed and Duplex settings in 2950 switch config

[peter.mainwaring]

When I am configuring a new 2950 switch, I sometimes copy and paste various parts of an existing config from another switch. As a matter of course, we tie down all user ports to 10Mb/Half, unless there is a good reason for them to run at 100Mb.

If you copy the config for a port from a switch as displayed from a SHOW RUN command and then paste it, you get the reply "Duplex can not be set until speed is set to non-auto value" because the duplex setting is listed above the speed setting.

What a pain in the neck this is!

I have got round it by editing the port config commands and saving it in a file on my PC, but I am not always in a location where I can access this file.

We are running 12.1(14)EA1a on our switches at the moment. Does anyone know if this anomoly has been corrected in any later releases?

Thanks,

Pete

[aashish.c]

Hey Pete

You cant set the duplex unless you set the speed to either 10 or 100. This is not a bug of any IOS, this is the way it works.

Incase if you set the speed to AUTO then automatically duplex sets to AUTO. bcoz between 2 links first speed is negotiated and then type of duplex is determined.

[peter.mainwaring]

Thanks for the reply.

I know that you can't set duplex unless you set the speed, but that isn't the point I was making. If you do a SHOW RUN, the DUPLEX setting appears above the SPEED setting on the display. If you then copy and paste that onto another switch, it says that you can't set duplex until you have set speed (as you quite rightly say). The point is, why is it listed in this order on a SHOW RUN when you can't configure it in this order on a switch?

...and hence the other question - is this corrected in a later release (the order on a SHOW RUN that is)?

Pete

[pmajumder]

Hello Peter,

It is a pain. I run 12.1(19)E1, and it's the same. I use the Interface range command. At least you only have to make the correction once for all the ports instead of doing it for every interface - not sure if this cmd is available on your version.

Regards

Pradeep

[aashish.c]

Hi,

You can use range command on your 2950. It will very much work.

switch(config)#int range fa0/2 - 8

[peter.mainwaring]

Well, as they say, you learn something new every day!

I've never spotted the range parameter under the config interface command before. Now that really is useful.

Thanks very much for that one guys.

Pete

[peter.mainwaring]

This has now been corrected.

Extract from Release Notes for the Catalyst 2955, Catalyst 2950, and Catalyst 2940 Switches, Cisco IOS Release 12.1(22)EA1 :-

This release contains these new Catalyst 2940, 2950, and 2955 switch enhancements:

•You can configure the duplex setting when the speed is set to auto.

Pete

[scottosan]

What are you trying to accomplish by setting all ports to half duplex. This will introduce unneccessary errors and collisions on all of your ports. Definately not the best way to control bandwidth.

[peter.mainwaring]

It is the 10Mbps that we are more interested in really. I don't like setting ports to auto because that invariably leads to many more problems that running 10Mbps/Half.

Also, we have a large number of diskless workstations onsite, connecting to a Citrix server farm, so 10 Mbps is plenty fast enough for those. We give everyone 10Mbps by default and up them to 100Mbps/Full if they need it for any reason. We have to set some ports to 100Mbps/Half as well because they run very slowly if they are set to 100/Full (I put this down to the card drivers, but in many cases there doesn't seem to be a later driver available - or the system administrators can't be bothered to look for the latest - one of the two).

Half duplex shouldn't introduce errors if all components are working correctly. Obviously, there will be collisions, but that is the way in which ethernet is supposed to work.

However, looking at the low level of utilisation on the Gigabit uplinks, it looks as though we could set everything to 100/Full (or 100/Half as appropriate) without any problems.

Pete