How to modfy speed for LAN device

[Chaim Budnick]

I need to modify the speed of a LAN device to 100 and to set it as DUPLEX, and I haven't the slightest idea how this is accomplished.

I tried invokinp LANCP help, but I could NOT find anything helpful.

Chaim

[David B Sneddon · Accepted solution]

Chaim

MCR LANCP SET DEVICE ewa0 /SPEED=100/FULL_DUPLEX/MEDIA=TWISTEDPAIR

or replace ewa0 with whetever your device is

Regards
Dave

[Chaim Budnick]

THANKS !!!!

What is the /media=twited ?

Chaim

[Antoniov.]

Chaim,
medit=twisted set RJ45 port; on some old alpha server there was the BNC connector too to you could set BNC instead twisted pair.

Antonio Vigliotti

[Bojan Nemec]

Chaim,

To see the device characteristics do

LANCP> show device /characteristics DEV
or
LANCP> show device /parameters DEV

You will see how the device is configured.

Bojan

[Chaim Budnick]

Another question:

Does the SET command modify both the volatile and permanent database. I.E. when the system reboots will the new settings be kept with the set command?

Chaim

[David B Sneddon]

To save the setting, use DEFINE rather than
SET. SET does the volatile, DEFINE does the
permanent.

Dave

[Chaim Budnick]

Thanks!

So, in fact I have to enter he same command TWICE, once with SET and once with DEFINE? Is this correct?

Chaim

[David B Sneddon]

The help seems to indicate that the two commands
are required.

Dave

[Chaim Budnick]

I think I can answer my own last question:

I should use:

define ewao /volatile

Chaim

[David B Sneddon]

That was the other way of doing it.
Then again, if you can shut the machine down
you can "set ewa0_mode fastfd" at console
level.

Dave

[John Gillings]

A warning about setting LAN speeds!

Most modern switches (especially unmanaged ones) use autonegotiation to determine their settings. The protocol does NOT work if the host port is hard set. The switch will be able to identify the speed, but cannot identify the duplex setting, and will therefore choose HALF DUPLEX.

The mismatch won't be noticed for low levels of activity, but will cause random packets to be dropped when the network is pushed harder. This manifests as numerous different symptoms, mostly reduced performance.

So, if you connect your OpenVMS system to an unmanaged switch you MUST set the host port to AUTONEGOTIATE. If you wish to choose a particular setting, like 100 FULL DUPLEX, then you MUST set the switch port to the same setting as the host.

The latest LAN patches (post September 2004) contain code to detect a duplex mismatch and issue an OPCOM warning. This doesn't fix the mismatch. If you see the warning, you need to take steps to resolve it by changing the settings on the host and/or switch so they match.

[Uwe Zessin]

Good point. If possible I try to do a little 'load test' with DTSEND or TCPIP$TTCP to find out of throughput is within a reasonable range.

[Didier Ravagli]

And what about the command
>>> set ewa0_mode FASTFD
under the SRM prompt ?

[Uwe Zessin]

You mean what David Sneddon suggested yesterday?

That is fine, too and even required if you boot via a LAN interface.

[Antoniov.]

Chaim,
if you will set autonegotiation to make simple your work you can type in SRM
>>> set ewa0_mode auto
or in vms
$ MCR LANCP SET DEVICE EWA0 /AUTO
this option always works with switch; usually switch and NIC use 100Mbs and Half Duplex.
As John posted, switch and NIC have some trouble if you dont't set both in the same way.

Antonio Vigliotti