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Operating System - OpenVMS
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How to modfy speed for LAN device

 
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Chaim Budnick
Regular Advisor

How to modfy speed for LAN device

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
15 REPLIES
David B Sneddon
Honored Contributor
Solution

Re: How to modfy speed for LAN device

Chaim

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

or replace ewa0 with whetever your device is

Regards
Dave
Chaim Budnick
Regular Advisor

Re: How to modfy speed for LAN device

THANKS !!!!

What is the /media=twited ?

Chaim
Antoniov.
Honored Contributor

Re: How to modfy speed for LAN device

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
Antonio Maria Vigliotti
Bojan Nemec
Honored Contributor

Re: How to modfy speed for LAN device

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
Regular Advisor

Re: How to modfy speed for LAN device

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
Honored Contributor

Re: How to modfy speed for LAN device

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

Dave
Chaim Budnick
Regular Advisor

Re: How to modfy speed for LAN device

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
Honored Contributor

Re: How to modfy speed for LAN device

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

Dave
Chaim Budnick
Regular Advisor

Re: How to modfy speed for LAN device

I think I can answer my own last question:

I should use:

define ewao /volatile

Chaim
David B Sneddon
Honored Contributor

Re: How to modfy speed for LAN device

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
Honored Contributor

Re: How to modfy speed for LAN device

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.
A crucible of informative mistakes
Uwe Zessin
Honored Contributor

Re: How to modfy speed for LAN device

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
Occasional Visitor

Re: How to modfy speed for LAN device

And what about the command
>>> set ewa0_mode FASTFD
under the SRM prompt ?
Uwe Zessin
Honored Contributor

Re: How to modfy speed for LAN device

You mean what David Sneddon suggested yesterday?

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

Re: How to modfy speed for LAN device

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
Antonio Maria Vigliotti