[Info-vax] tcpip gateway question

[jbriggs444]

On Sep 8, 9:25 am, Anton Shterenlikht <me... at bristol.ac.uk> wrote:
[snip me asking about duplicate IP address]
> I don't think so. This ip address has been with this interface for
> several years now (it was a stand-alone box). Running nmap 137.222.187.238
> from other boxes doesn't find any other nodes.

As a stand-alone box it had just the single interface active?  Or
both?  And was the 137.222.187.238 interface working for TCP/IP
previously.

There is a possible hair-brained diagnosis that has occurred to me.
What if both the front-side and back-side cables are connected to the
same VLAN or if the front-side and back-side VLANs are somehow cross-
connected elsewhere.  That kind of misconfiguration would be largely
symptom-free.

But in that case and if both front-side and back-side Ethernet
adapters are running with the DECnet MAC address then you could have a
MAC address conflict on your hands.  That conflict will tend to be
resolved in favor of the adapter with the most [recent] outbound
traffic.