topic Re: Two Mac addresses in Operating System - OpenVMS

Two Mac addresses

matthew robey — Tue, 22 Feb 2005 18:05:58 GMT

Hello there,

OpenVMS V7.3-2
TCPIP V5.4 Eco 4
Decnet V (Over IP)

The nic has mac address of 00-02-A5-20-17-EB

the switch sees the mac address as AA0004000604

and a MC NCL SHO OSI TRANSPORT ALL gives

UID =
732992B9-84C7-11D9-862D-AA0004000604 (note the last 12 characters)

Any ideas why the switch doesn't see the address as 00-02 etc

Re: Two Mac addresses

David B Sneddon — Tue, 22 Feb 2005 19:19:42 GMT

Matthew,

When you configure DECnet V you have the option
of using Phase IV addressing. I assume you selected
YES to that option. DECnet is changing the MAC
address of the NIC to match your Phase IV DECnet
address. If you don't *need* the Phase IV addressing
you can turn it off and a reboot should show the
00-02... address.

Regards
Dave

Re: Two Mac addresses

matthew robey — Tue, 22 Feb 2005 19:24:01 GMT

Thanks Dave,

I was sure that I had seen this type of mac address before, but couldn't put my finger on it.

Matt

Re: Two Mac addresses

Robert Gezelter — Tue, 22 Feb 2005 21:22:58 GMT

Matt,

Concur with Dave. A further note. The DECnet Phase IV-ism with the MAC address is one of the reasons that DECnet needed to be started before the IP stack or LAT.

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

Re: Two Mac addresses

Antoniov. — Wed, 23 Feb 2005 02:36:08 GMT

yes,
this is the reason of decnet can't support two address on same server.

Antonio Vigliotti

Re: Two Mac addresses

Jan van den Ende — Wed, 23 Feb 2005 03:57:03 GMT

this is the reason of decnet can't support two address on same server.

...with one VERY IMPORTANT exception!

With DECnet, you can have a _REAL_ cluster alias, which is an other DECnet address!

That stupid IP has something they dare call that, but it is just a single-network device alias, that can fail over provided _NO_ active connections.

A DECnet alias is valid SIMULTANIOUSLY over ALL servers, and PER application you dedine your outgoing ID to be the server or the alias.

Proost.

Have one on me.

Jan

Re: Two Mac addresses

Wim Van den Wyngaert — Wed, 23 Feb 2005 06:59:15 GMT

It is possible to have 2 decnet addresses but both will be used to reach the destination, t.i. they are considered to be connected on the same network.

If the network is not the same, it is still possible to fool decnet by keeping the correct line open via a permanent job. We once did that (decnetplus using nsp transport).

Wim