[Info-vax] tcpip gateway question

[Richard B. Gilbert]

Richard Brodie wrote:
> "Anton Shterenlikht" <mexas at bristol.ac.uk> wrote in message 
> news:mailman.7.1253014955.18305.info-vax_rbnsn.com at rbnsn.com...
> 
>> On Tue, Sep 15, 2009 at 11:26:37AM +0000, Jan-Erik S?derholm wrote:
>>> DECnet when started change the MAC address. And it's built up
>>> based on the DECnet area.node address in som e way, if I'm not wrong.
> 
> Indeed, take last two bytes as little endian, 10 low bits node, 6 high area.
> Since you aren't spanning byte boundaries in this particular case this reduces
> to AA-00-04-00-node-(area*4).
> 
>> So really I either have to use EWB0 (second) interface instead of EWA0,
>> or disable DECnet?
> 
> I'm apparently missing some context here. Normally it doesn't matter; unless
> you have something like a MAC based security policy. Usually, start DECnet
> early and forget the real hardware address.
> 

"Start DECnet early" does not quite cut it!  You may start it early or 
late but you need to start it BEFORE you start TCP/IP.  If you start 
TCP/IP first and then DECnet you will change the ethernet address that 
TCP/IP is relying on!