In article <[log in to unmask]>, [log in to unmask]
u (Aaron Porter) writes:
>       Paging through the latest Linux kernel I came across DECnet support.
> It seems that the one and only person working on DECnet support is
> progressing rapidly.  My question is what's so great about DECnet?  What
> would speaking DECnet allow a UNIX box to do that it doesn't already?
 
DECnet is the native networking protocol for OpenVMS.  DECnet is similar to
TCP/IP in many ways.  It runs on top of Ethernet, FDDI, ATM, and other network
infrastructures.  It has objects which are similar to ports on TCP/IP.
It's got something similar to INETD (a connection comes in on a port/object
and automatically is handled by a particular program).
 
DECnet does not have an equivalent to DNS, though.  Each node must know the
address of every other node.  In addition, DECnet's addresses scheme is
only 16-bit (maximum of 65536 nodes) as opposed to TCP/IP's 32-bit
implementation (over 4 billion nodes).
 
I'm not sure about the Linux implementation, but DECnet on OpenVMS is very
well tied into the OS rather than being a layer on top.  For example,
DECnet is tied into the file system very well.  With this, I can use any
file on any DECnet node as if it were a local file.  For example, from
MiaVX1, I could issue a command like:
 
  $ TYPE MUMR2"kacovert mypassword"::LOGIN.COM
 
This will display the LOGIN.COM file in KACOVERT's account (using the
password mypassword) on the MUMR2 (Middletown) OpenVMS system.  If
something called proxies were enabled between the systems, I wouldn't even
need the username and password (similar to a .RHOSTS).
 
This is different from something like RCP, because the file isn't copied to
MiaVX1 first, it's just accessed as if it were a local file.  This is also
different from NFS in that I don't have to configure the file system for
each computer I want to access files from.  I just have to let DECnet know
about the other computer.
 
Miami stopped running DECnet natively on our network in January, 1996.
This was the beginning of an ongoing process to eliminate protocols on our
network.  Eventually, Miami would like to reduce our network to just IP
protocols (the only protocols left on our network that I'm aware of are IP,
AppleTalk, and IPX/SPX).  In January, 1996, we began tunnelling DECnet over
TCP/IP between our OpenVMS systems.  The tunnelling protocol we're using is
a Cisco (now Process Software) proprietary protocol.  Unless the Linux port
implements this proprietary protocol, you will not be able to use DECnet at
Miami.
 
--
                                     Kent Covert, Software Coordinator
                                     Miami Computing and Information Services
                                     Miami University, Oxford, OH
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