ewilts%Ins.MRC.AdhocNet.CA%Stasis.MRC.AdhocNet.CA%UNCAEDU.@CORNELLC.CCS.CORNELL.EDU.BITNET (Ed Wilts) (07/12/88)
DON'T buy third party! (that subtle enough for you :-)).
DEC cheats in their DECnet code and will only store the trailing 3 parts
(6 digits) of an Ethernet address. For example, if your ethernet address
is "08-00-36-e9-1e-00", DEC only uses "e9-1e-00". This is because the first
3 parts are reserved to the manufacturer. We have a third party Ethernet
controller made by Intergraph Corp., and it will NOT run DECnet. DEC assumes
that they know the first 3 parts because they have them reserved. In our
case, nothing we can do will convince DECnet to run on our controller. In
order to run DECnet, we must buy DEC's Ethernet controller.
DEC's statement on this is that they consider DECnet/Ethernet so important
in their corporate strategy that they don't trust anyone else to implement
it. If that sounds like a load of crock to you, then you must agree with me.
Anyway, buy a DEC controller...
.../Ed (ewilts%ins.mrc.adhocnet.ca@uncaedu.bitnet)
Ed Wilts
Sr. Systems Analyst
Canadian Occidental Petroleum Ltd.
Calgary, Alberta, Canadaleres@ace.ee.lbl.gov (Craig Leres) (07/17/88)
Ed Wilts writes: >DEC cheats in their DECnet code and will only store the trailing 3 parts >(6 digits) of an Ethernet address. For example, if your ethernet address >is "08-00-36-e9-1e-00", DEC only uses "e9-1e-00". This is because the first >3 parts are reserved to the manufacturer. We have a third party Ethernet This turns out not to be the case. Dec ethernet interfaces are like other manufacturers in that each board has a unique ethernet address. The block assigned to dec for unibus and qbus machines is 8:0:2b:?:?:?. So if you have an Vax running Berkeley Unix on it with a deuna, deqna, or delua on it, then its ethernet address will start with 8:0:2b. On the other hand, decnet requires stations use a "logical address" that is based on the node and area numbers. The block assigned to dec for this purpose is aa:0:4:?:?:?. So if you have a machine running decnet on ethernet, its ethernet address with start with aa:0:4 and will end with three octets determined by your node and area numbers. Unfortunatly, I don't have the calculation handy, but I think it works like this: the 4th octet is always zero, the 5th octet is the node number and the 6th octet is the area number shifted left 2 bits. So node 1 in area 1 is aa:0:4:0:1:4. Note that the only reason it's possible to change the hardware ethernet address is because dec wanted/needed this feature for decnet and they were one of the companies who drew up the ethernet specification. > We have a third party Ethernet >controller made by Intergraph Corp., and it will NOT run DECnet. DEC assumes The reason you can't run decnet on your ethernet interface is not because decnet doesn't support it but because VMS doesn't support it. If you wrote a vax/vms device driver for your board which supported the "alt start" internal interface, it should be possible to run decnet on it. > DEC assumes >that they know the first 3 parts because they have them reserved. In our As I explain above, they assume they know the first three octets because the protocol (stupidly) requires it. Getting back to the original question, if you want to run decnet, then you're better off buying a dec ethernet interface; writing a vax/vms driver that supports decnet is not a trivial job. (The deuna driver is something like 2000 or 3000 lines of assembler.) But if you want to run tcp/ip only (using one of the Wollongong or Multinet packages) and don't care about decnet, then you can buy nearly any interface that is supported by BSD Unix. Craig