Xref: utzoo comp.protocols.misc:276 comp.dcom.lans:1417 comp.protocols.tcp-ip:3663
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From: duncan@comp.vuw.ac.nz (Duncan McEwan)
Newsgroups: comp.protocols.misc,comp.dcom.lans,comp.protocols.tcp-ip
Subject: Linking LAN's via Public X.25
Message-ID: <13652@comp.vuw.ac.nz>
Date: 26 May 88 04:52:34 GMT
Organization: Comp Sci, Victoria Univ., Wellington, New Zealand
Lines: 38

I need to find out what products are available for linking two geographically
remote LAN's via a public x.25 network.

I have advertising glossies for Sun's SunLink X.25 product which seems to
provide the desired facilities, but which leaves some questions unanswered.

From what I can tell SunLink X.25 does allow carrying IP packets from one lan
to another via an x.25 virtual circuit.  What I would like to know is how
transparent this is.  Does one host on the local ip lan (not necessarily the
Sun running SunLink x.25) just ask to send an ip packet to a node on the remote
lan, causing SunLink X.25 to open a VC to transmit the packet?

Assuming this is the way it works, does SunLink multiplex datagrams from
several tcp or udp sources over the one VC, and if so, at what point does it
close the VC?  Are the local and remote lans on different class C ip networks
(I guess they must be to allow packets to be routed to the host with the x.25)?
How are the ip addresses mapped into x.121 addresses?  Finally from an economic
point of view how reasonable is it to send ip over x.25 bearing in mind the
relatively large tcp + ip headers, particularly when you are paying for both
connect time and number of segments sent (a segment is 64 octets, and NZ
telcoms charge for unfilled segments as one full one).

Enough about SunLink x.25 specifically!  Are there any other products (bridges,
routers, other computer vendors x.25 packages) that offer this type of
functionality.  In particular, do HP offer anything similar?  Can one companies
product interoperate with anothers (for example, I believe that the Multinet
IP/TCP package for VMS does/will offer some facility for tcp/ip over x.25 - is
it reasonable to expect a Sun running SunLink x.25 to be able to talk IP with
it).

I think that is enough questions for one article!  Any answers to some or
all of the above will be appreciated.  Answer by email and if there is
any demand I will summarise.

---
Duncan

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