[Info-vax] Rethinking DECNET ?

[Jan-Erik Soderholm]

Johnny Billquist wrote 2014-09-04 00:53:
> On 2014-09-03 16:53, Dirk Munk wrote:
>> Johnny Billquist wrote:
>>> On 2014-09-02 20:26, Dirk Munk wrote:
>>>> Johnny Billquist wrote:
>>>>> On 2014-09-02 09:52, Dirk Munk wrote:
>>>>>> JF Mezei wrote:
>>>>>>> (so tunneling DECNET 5 over IP is not the same as having FAL be
>>>>>>> native
>>>>>>> on IP).
>>>>>>
>>>>>> It is >>not<< tunneling. Decnet 5 uses TCP+IP as transport layer
>>>>>> instead
>>>>>> of OSI. Decnet 5 hosts have IPv4 and/or IPv6 addresses and BIND DNS
>>>>>> names, not OSI addresses in this case. In fact Decnet 5 is doing
>>>>>> exactly
>>>>>> what you're asking from a redesigned Decnet 4 stack, however it is
>>>>>> using
>>>>>> only one TCP port, port number 102.
>>>>>
>>>>> You know, this actually *is* tunneling. :-)
>>>>> You have one DECnet stream over TCP/IP. Inside that stream goes DECnet
>>>>> traffic, which might actually be several different streams that are
>>>>> multiplexed on this tunnel. And DECnet have no idea how the two
>>>>> endpoints connect, and how many hops might be along the way in the IP
>>>>> world. It's a tunnel.
>>>>
>>>> And that is exactly the same as with OSI. With IP you address port 102,
>>>> and with OSI you address protocol selector 20 (hex) for DNA (Decnet
>>>> Phase V) traffic, and protocol selector 21 for NSP (Decnet Phase IV)
>>>> traffic.
>>>
>>> And? It's still a tunnel.
>>>
>>>      Johnny
>>>
>> No, it is not a tunnel. There is no principle difference between Decnet
>> over OSI and Decnet over IP. The transport layer is different, that's all.
>
> DECnet over OSI? What does that mean? You say it like you are implying that
> OSI is a separate network protocol from DECnet. DECnet phase V *is*
> following the OSI model, not running atop of it.
>
> With DECnet over IP, the transport layer is actually a whole full other
> network stack, of which DECnet is totally unaware of.
>
>      Johnny
>

As I understand, and I think we have to separate protocols from
network architectures here, one can summerize it something like:

DECnet IV is communication based on "DIGITAL Network Architecture" (DNA).
DNA is a 8 level architecture different from both OSI and the
architecture used by IP.

DECnet V  is communication based on "Open Systems Interconnection" (OSI).
DECnet V was also called "DECnet/OSI" to emphasize its OSI architecture.

DECnet V+ (or DECnet-Plus) added support for IETF RFC 1006 ("OSI over IP").
http://tools.ietf.org/html/rfc1006

And since "DECnet over IP" is based on the specification for "OSI over IP",
I'd guess that you can't easily shoehorn that into DECnet IV. Either you
would change DECnet IV to use the ISO model (but then you have DECnet V),
or you develope a whole other interface to IP not based on "OSI over IP".

And if you still *need* DECnet (I have not used it for anything on my
production systems the last decade, they are IP-only), you might
better learn and used DECnet V+.

Jan-Erik.