topic Re: Disadvantage with using autoneg on gigE cards.... in Operating System - Linux

Disadvantage with using autoneg on gigE cards....

hp_user_1 — Thu, 29 Jan 2009 20:27:35 GMT

Hi,

I have a number of servers in my environment and all of them have gigabit interfaces set to 100fd/auto off. I was told that 1000fd/auto on does not function well. Any comments....

Thanks

Re: Disadvantage with using autoneg on gigE cards....

James R. Ferguson — Thu, 29 Jan 2009 20:34:14 GMT

Hi:

With gigabit LAN cards you want to set both the switch and the card to auto-negotiate.

With the old 100MB cards auto-negotation was notorious for not working well and the advice was to set those to 100MB and full-duplex.

Regards!

...JRF...

Re: Disadvantage with using autoneg on gigE cards....

hp_user_1 — Thu, 29 Jan 2009 21:13:08 GMT

My servers are rp7410, rp7420, rp4440 and running 11i v1 and v2. These servers should have later model cards. Has anyone experienced any issues with 1000fd/auto on?

Re: Disadvantage with using autoneg on gigE cards....

Duncan Edmonstone — Thu, 29 Jan 2009 21:19:56 GMT

Auto-negotatiation was a pain with fast ethernet (100BaseT) and didn't always work correctly, but for GbE, you should always use it if your switch is GbE capable as well.

The simple rule for GbE NICs is:

If your switch ports are GbE capable rather than just 100FD, then leave auto-negotiate on.

If your switches are only 100FD, you should experiment with auo-neg at both sides to see if it works correctly - if not, tie both ends down to 100FD.

Follow that and you can't really go wrong.

HTH

Duncan

Re: Disadvantage with using autoneg on gigE cards....

hp_user_1 — Thu, 29 Jan 2009 21:31:45 GMT

My switches are Cisco 3500 series and they do support 1000/autoneg...

Re: Disadvantage with using autoneg on gigE cards....

Patrick Wallek — Thu, 29 Jan 2009 21:36:49 GMT

I have a number of servers with gigabit NICs. In order to get gigabit speed you MUST set both ends to AUTO.

Cards I have on HP-UX will not allow a manual 1000FD setting. It must be AUTO for gigabit speed.

I have not had any trouble maintaining gigabit speed setting with AUTO on the NIC and switch ports.

Re: Disadvantage with using autoneg on gigE cards....

hp_user_1 — Fri, 30 Jan 2009 00:22:17 GMT

I am going to modify the settings to auto/auto on one of the servers and let it run for a week or so, and then roll out to other servers...

Thanks for all the help;

Re: Disadvantage with using autoneg on gigE cards....

rick jones — Fri, 30 Jan 2009 00:30:25 GMT

Make sure that NIC/Host and Switch _match_ per the attached.