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openvms ...

v.saravanan_1
Frequent Advisor

openvms ...

What is the difference between the decnetIv and decnet V ? plz explain briefly ...
8 REPLIES
Karl Rohwedder
Honored Contributor

Re: openvms ...

DECnet IV and DECnet V are 2 incarnation/levels of the DECnet protocol suite. Version V is newer and implements the OSI model of networking.
A main difference to the 'normal' user/admin is, that it supports the use of the TCP/IP protocols for the lower levels of the protocol stack, thus eliminating non_TCP protocols on the 'wire'. This is mandatory at many sites today. Pls. also note, that the management of both is different, but version IV is still supported.

regards Kalle
Wim Van den Wyngaert
Honored Contributor

Re: openvms ...

With the decnet product you can support phase 4.

With the decnet+ product you can support phase 4 and 5. Note that the phase 4 is another implementation of than that of the decnet product. For phase 5 support, you routers must be phase 5 enabled.

We use decnet+ in phase 4 mode.

Wim
Wim
Wim Van den Wyngaert
Honored Contributor

Re: openvms ...

BTW : please try to use different titles for different questions. Otherwise we think it's the same question asked twice.

Wim
Wim
Volker Halle
Honored Contributor

Re: openvms ...

... and the network management is different:

NCP for DECnet IV
NCL for DECnet-Plus (aka Phase V)

More details could be found in the SPDs (Software Product Descriptions):

DECnet Phase IV:

http://h18000.www1.hp.com/info/SP4848/SP4848PF.PDF

DECnet-Plus (Phase V):

http://h18000.www1.hp.com/info/SP5045/SP5045PF.PDF

and in the OpenVMS Documentation:

http://h71000.www7.hp.com/doc/

Volker.
Robert Gezelter
Honored Contributor

Re: openvms ...

vl,

It may not be clear from the previous posts.

Phase IV supports the NSP series of protocols developed as part of the original, traditional DECnet product.

Phase V suuports other protocols, notably the ISO OSI series and connections over an (external) TCP/IP stack. Running Phase V requires different routers IF (and ONLY IF) the new protocols are used. It is possible, and quite normal for a Phase V node to exist in an otherwise Phase IV network.

Phase IV remains supported because it is far simpler to administer. If you are not using the enhanced functionalities of Phase V, Phase IV is quite functional, if you are working in a DECnet environment. If you need to use IP tunnels, or the OSI protocol set, you will need to use Phase V.

- Bob Gezelter, http://www.rlgsc.com
(user of both Phase IV and Phase V, in house and out)
Arch_Muthiah
Honored Contributor

Re: openvms ...

Saravanan,

The two versions of DECnet are DECnet Phase IV and DECnet plus (DECnet V).

DECnet is developed under the framework of the Digital Network Architecture (DNA), which is a comprehensive layered network architecture that supports a large set of proprietary and standard protocols.

The DECnet Phase IV DNA is similar to the OSI architecture, which utilizes a seven layered approach. However, the Phase IV DNA is comprised of eight layers. The DECnet Phase IV DNA specifies four upper layers to provide user interaction services, network-management capabilities, file transfer, and session management. Specifically, these are referred to as the user layer, network management layer, network application layer, and session control layer.

The DECnet phase V (or DECnet Plus or DECnet/OSI) defines a layered model that implements three protocol suites: OSI, DECnet, and TCP/IP. DECnet plus conforms to the seven-layer OSI reference model and supports many of the standard OSI protocols. DECnet plus provides backward compatibility with DECnet Phase IV and supports multiple proprietary Digital protocols. DECnet plus supports functionality in the application, presentation, and session layers. The TCP/IP implementation of DECnet plus supports the lower-layer TCP/IP protocols and enables the transmission of DECnet traffic over TCP transport protocols.


Archunan
Regards
Archie
Arch_Muthiah
Honored Contributor

Re: openvms ...

Saravanan,

You can find DECnet Phase IV Specifications here...
http://ftp.digital.com/pub/DEC/DECnet/PhaseIV/

and DecNet Plus on http://h71000.www7.hp.com/doc/82final/decnetplus/int_use.pdf


Archunan
Regards
Archie
Colin Butcher
Esteemed Contributor

Re: openvms ...

Providing an understanding of DECnet Phase IV and Phase V is one of the reasons I wrote this for publication in the HP OpenVMS technical journal: http://www.downloads.xdelta.co.uk/vmstjv5%20feb2005/decnet%20article%20vms%20tj%20v5%20feb2005.pdf

As other have pointed out, there are also the manuals. If you really want to get into the detail then you can also search for the "Functional Specifications" for both Phase IV and Phase V, especially if you're in a support centre with access to the internal HP documentation.

Hope that helps.
Colin.
Entia non sunt multiplicanda praeter necessitatem (Occam's razor).