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From: karsten@tfl.dk
Newsgroups: comp.sys.dec
Subject: Re: DECnet Level 1 and Level 2 Routing
Message-ID: <1990Nov10.165132.102@tfl.dk>
Date: 10 Nov 90 15:51:31 GMT
References: <1990Nov9.190156.14366@Shiva.COM>
Organization: TFL, A Danish Telecommunication Research Laboratory
Lines: 25

In article <1990Nov9.190156.14366@Shiva.COM>, nik@Shiva.COM (Nik Langrind) writes:
> Is it ever permissible for a DECnet level 1 router to send a
> message to an area router outside its own area?  My reading of the
> Routing spec indicates "no" but I'm unsure of the meaning of the 
> term "nearest level 2 router," so perhaps it is permitted.  The 
> implementation that I'm maintaining (which is an Ethernet level 1 
> router) will forward to an area router outside its area.  The area
> router (a VAX) accepts and routes the message.  A VAX Level 1 router
> on the other hand, would have forwarded only to an area router in its 
> own area.

A level 1 router (or end node) may only talk to nodes, i.e.,
end nodes, and routers in its on area.  If a level 1 router
(or end node) wants to talk to any node, included area
routers, in an other area, it must let its messages pass the
nearest area router in its own area.  However not all third
party products follow the rules.  Sunlink (from Sun) allow
(or allowed) you to communicate directly from a Sun to an
node in an other area and if the other node is an end node
and the address of the Sun is cached then also the the other
way.

Karsten Nyblad
TFL, A Danish Telecommunication Research Laboratory
E-mail: karsten@tfl.dk