Path: utzoo!attcan!uunet!ginosko!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!APOLLO.COM!hanlon
From: hanlon@APOLLO.COM (OSI Steamroller is a comin')
Newsgroups: comp.protocols.iso
Subject: Re: What is Multilink Protocol?
Message-ID: <8907211330.AA00452@xuucp.ch.apollo.com>
Date: 21 Jul 89 13:26:02 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 31


     
New for 1984 CCITT X.25, Multilink Protocol performs the function of
distributing packets across available data links 
and resequencing packets for delivery to the packet level.

This procedure has been available for sometime in X.75 and it allows
the grouping of multiple physical lines at Level 2 (data link) X.25
to appear as a single logical line (benefits: throughput, 
resiliency among others) to Level 3 (packet) X.25.

This protocol is carried in a two-octet field within an I-frame
of LAP-B (LAP doesn't support Multilink).  The protocol's main
responsibilities are to maintain sequencing, prevent duplication,
and protect against packet loss.

Details of the protocol should be in the CCITT X.25 1984 spec 
(in my copy it's in section 2.5).  CCITT Multilink used ISO DIS 7478
"Multilink Control Procedure" as the reference.

                                        
I'm not aware of any PDNs/VANs that support mutlilink at X.25 but
I've been out of the X.25 arena for a couple of years....


Bart Hanlon                        UUCP:     ...{mit-eddie,yale,uw-beaver}!apollo!hanlon
Apollo Division/Hewlett Packard    INTERNET: hanlon@apollo.com
Chelmsford, MA 01824               Phone:    (508) 256-6600


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