[c-nsp] Decnet, LAT, MOP ... anybody?!?

[Netfortius]

I am having a little problem with a setup, in regards to some VAX machines on 
two different LANs. Here is the data:
- client needs the functions on the VAX machines, but nobody remembers who put 
them in;
- the VAX machines talk Decnet across a BRIDGED setup across their WAN link
- the setup was bridged, because this is how the previous routers were 
configured (nortel), so the people having installed Cisco just enabled 
bridging, also (!)
- nobody could tell if what is running really needs bridging
- Decnet could be routed, but we are not sure what conversations we could 
identify to point to the need for bridging
- sniffing at one end I have seen some LAT and MOP traffic, but none of that 
would appear to leave the confinement of a LAN (except for broadcasts)
- nothing could be changed on the VAX machines (no IP, no ...)

Question: short of disabling bridging and enabling Decnet, then testing and 
see if the systems fail, is there a specific type of traffic I could look 
for, sniffing at either end, or both, that would reveal the need for bridging 
(vs. routing exclusively)?

Right now - as I said earlier - I have a sniffer on the span port of one 
site's router, with the following filter:

$ sudo tethereal -s 1514 -w dec-related.cap 'decnet or lat or moprc or mopdl'

but I am not sure if I am missing something, or how to interpret part of the 
traffic (as in "does it really need bridging, or not"?).

Any suggestions?

TIA,
Stefan