Network performance

[David Z. Brown]

I moved a DS20 off of a HP Procurve 4108gl with the nic set to 100 MB full to a HP Procurve switch 5308xl and the transfers speed deteriated to the extend that FTP jobs that completed almost immediately to transfers talking up to 20 minutes. The 5308 is set to auto and the nic on the DS20 is set to 100/full. Does anyone have any ideas what could be causing the deteriation in performance? We have tried a variety of settings but knowing seems to help.

[Robert Gezelter]

David,

Check to see if the port on the switch has autonegotiated itself to half duplex.

One of the more common reasons for dramatic drops in performance is the lost packets due to one port being set to FULL and the other side being set to HALF.

This should also show up in the IP statistics.

- Bob Gezelter, http://www.rlgsc.com

[David Z. Brown]

Forcing it 100/full on the switch didn't seem to change anything. It is on 100/1000 port does that cause any issues of concern.

[Robert Brooks_1]

Absent something quite wrong, the relevant LAN drivers on a modern version of OpenVMS Alpha should correctly autonegotiate with the switch, assuming a correctly-behaving switch. I'd try setting EWA0_MODE (or whatever the relevant variable is for your device) to auto-negotiate
and retry the experiment.

What version of OpenVMS Alpha and what type of ethernet card?


-- Rob

[David Z. Brown]

The OS is VMS 7.3-1 and the nic is one of the 600 series. The letters escape me right now. But they are 10/100 cards and the 5308 is 10/100/1000. When we plugged the NIC back into a 4108 it started the performance improved. But we need to get it working in the 5308 because we are going to get rid of the 4108's. Thanks for the suggestion on the Exxx_mode. I will try that.

[Cass Witkowski]

YOu can use MC LANCP
SHOW DEV EIx0 /char to determine how your current EI device is configured speed and duplex wise. They should match your switch.

You can use LANCP to to change the settings immediately rather than having to reboot. However, it may affect any connections on that network device.

Once you get settings to work then be sure to set the proper EIx0_mode and then do an init to make them permanent.

If you can try using ping with a large data size of 10,000 bytes to stress the network connection a bit. This tends to show packet loss that the standard 64 byte ping packet won't.

[John Gillings]

David,

The rule for network adapter speed settings is very simple. Both ends of the wire need to be set identically. That is, if one end is set to AUTONEGOTIATE, then so must the other end.

If one end has any hard setting (ie: 100/FD) then the other end must be set the same.

This is arguably a flaw in the autonegotiation algorithm, but don't expect it to ever change. It's just something we have to live with.

Since most switch and hub ports deault to AUTO, I recommend that all host adapters also be set to AUTO.

For some reason, many OpenVMS people still believe a mythology that autonegotiation doesn't work properly on Alphas and/or OpenVMS. This is not correct. Hard setting network speeds frequently results in reports that read just like yours. Drammatic reductions in network performance (or just about any other kind of performance!).

[David Z. Brown]

Thanks to all for your input and support. This is and always has been a great forum. So this VMS bigot will close this thread for now and go do some patching of 7.3-1 since the powers to be won't let me take it to 8.2-1 for now.

[Robert Gezelter]

David,

re: Cass' comment about large pings.

A good check is to do more than one simultaneous transfer in each direction. You will be surprised how many network configuration problems only show up when the traffic volume is significant. With today's networks, it is often a good idea to move several gigabytes (or tens of gigabytes) through a connection before deciding that all of the settings are correct.

- Bob Gezelter, http://www.rlgsc.com

[David Z. Brown]

Thanks again to all. You will see me out here more often. Sorry for my absense in participating with my fello VMSers!!