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

[Netfortius]

On Thursday 06 April 2006 14:03, Brian McMahon wrote:
> On Apr 6, 2006, at 11:48, Netfortius wrote:
> > 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;
>
> [...]
>
> > - 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)
>
> LAT for sure, and I think MOP as well, are layer 2 protocols, and
> *must* be bridged.  No layer 3 info, MAC addresses only, nothing to
> route.
>
> LAT .ne. DECnet.  DECnet (there's Phase IV, which is what you
> probably have, and Phase V, which is based on the OSI protocol stack
> (remember when that was going to be the way of the future?)) is
> routable, assuming that you have an IOS feature set that speaks DECnet.
>
> But if your important access is via LAT anyway (mostly seen for
> communication with terminal servers and printers), then you're stuck
> bridging that no matter what.
>
> *WOW*, it's been a long time since those neurons woke up.
>
> --
> Brian McMahon <brian dot mcmahon at cabrillo dot edu>
> Computer Networking and System Administration Instructor
> Cabrillo College, Aptos, California

Thank you for your reply. This is the challenge - I mentioned LAT and MOP as I 
know they are not routable, but I cannot tell if the traffic I am seeing is 
in real need for bridging or if I see it because it is bridged (does it make 
sense? - this is the only way I could describe my problem). 

For example - I am seeing conversation between an interface of one VAX on one 
LAN (that weird MAC address which is specific to DEC), and the Ethernet 
interface of the Cisco router - which, if it was to be routing - would have 
been indicative of need to cross the boundaries, but which - being that it is 
identifying by tethereal as LAT, makes me wonder if it is not in fact just 
some broadcast reaching the router, but with no need to traverse it.

Also - as all the VAXes on either side are supposed to boot locally (MOP 
part), I am wondering if the traffic I see being MOP related is not - in 
fact - visible just because I am bridging, not that it really needs to cross 
LANs ...

Thanks again,
Stefan