SV: RE: [HECnet] Hecnet and DDCMP - HECnet

3 Jan 2012

Johnny,

First and foremost, I want to learn how to configure and understand how these devices
connected historically so I can troubleshoot the connectivity.   This gives me the best
feeling of true understanding.   Unfortunately, I don't have a slew of these systems
(I have a single Microvax II) that I can use to interconnect, so I am locked into
simulating at least one end of the connection.   I was hoping to do this with simh.  
Secondly, I was hoping to create error conditions and determine whether I can diagnose the
problem.

As this is legacy hardware, protocols, and otherwise, I understand that aside from
understanding how some of our modern protocols and systems emerged from knowledge of the
old systems.   I am I really hoping to start a little further back to solidify my
understanding of modern technology without all of the additional layers of distraction
included with modern systems.

Did the VAX/VMS platform have an option to include PPP or SLIP previous to decnet +?   I
have a good knowledge of these protocols.   I used slip back in the day when I had to
connect with a pr1mos system that wouldn't allow pass-through connection to the
internet.   PPP, especially multilink using PPP I have implemented multiple times (even
recently...silly, but I didn't choose).   My ultimate goal is to pass decnet phase IV
(not plus) traffic over the connection.

Thanks,
Kevin

...
  Date: Mon, 2 Jan 2012 11:15:34 +0100
 From: bqt at softjar.se
 To: hecnet at Update.UU.SE
 Subject: Re: SV: RE: [HECnet] Hecnet and DDCMP

 The biggest issue I don't understand here is why.
 If you tunnel a serial port, you tunnel a serial port. DDCMP is totally 
 invisible to you.

 You will not learn, or need to understand anything about DDCMP for this. 
 A serial port sends bytes. You pass those bytes one. Everyone is happy.

 What kind of protocol is implemented, using those bytes, are very 
 invisible and irrelevant to the tunnel, just as it is to a cable.

 You might as well tunnel SLIP, or PPP. It will work just the same.
 They are all just implementing a network layer on top of a serial 
 connection.

 What are you really trying to accomplish?

 Johnny

 On 2012-01-01 01.57, The Presence wrote:
  Bob,

 I really am wanting to use DDCMP for learning purposes. I want to build
 a decnet phase IV network with DDCMP, however, I want to also have the
 ability to pass traffic through to connect to additional nodes that are
 net connected.

 Kevin

 ------------------------------------------------------------------------
 To: hecnet at Update.UU.SE
 Date: Sat, 31 Dec 2011 16:41:02 -0800
 Subject: Re: SV: RE: [HECnet] Hecnet and DDCMP
 From: bob at jfcl.com

 What is it that you actually want to connect? For the most part, a
 Multinet link simulates the "user experience" of a DDCMP connection
 tunneled over IP. Multinet is a point-to-point DECnet circuit which,
 except for the device names, is functionally identical to any DDCMP link.
 The only reason I can see for using a real DDCMP serial connection
 (either sync or async) would be to connect a machine that didn't support
 an Ethernet interface.
 Bob