Re: Routing thru X.25 from a cisco to a Sun?

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4 total messages Started by Steve Feldman Thu, 23 Aug 1990 09:12

#597

Author: Steve Feldman
Date: Thu, 23 Aug 1990 09:12

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We ran into a problem when we tried this a year or two ago.  There is a
philosophy difference between cisco and Sun on how IP routing over X.25
should be done.  cisco routers like to treat an X.25 network as a
single multi-point network, where each router has a list of X.121
addresses corresponding to the IP addresses for each other router, and
will build circuits on demand and close them after an inactivity
timeout expires.  (This is similar to the way DDN X.25 operates, I
believe.)

Sun's X.25 over IP implementation, however, likes to treat the X.25
network as a collection of permanent point-to-point links, each with
its own network or subnet number.  It also insists that one end of
each link be responsible for ensuring that the circuit is up at all
times.

We did get the Sun to talk to the cisco router, but we had these problems:

1) Since the cisco assumed that each router on the X.25 network
was directly connected to each other one, it refused to route an
IP packet back over the same X.25 interface it came in on.

2) The cisco liked to build parallel X.25 circuits to the same destination.
Sun's x25manager barfed at this.  I think there might have been a way to
disable this on the cisco, but I'm not sure.

3) The Sun had to take the responsiblity for keeping the circuit up,
since it doesn't do circuit building on demand.

We did these experiments over a year ago, so perhaps cisco has changed
their implementation to get around these problems.  I'm pretty sure
that Sun hasn't done anything about it.

	Steve Feldman
	BT Tymnet, Inc.
	feldman@Tymnet.COM

Re: Routing thru X.25 from a cisco to a Sun?

#598

Author: Robert Smart
Date: Fri, 24 Aug 1990 01:09

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In article <25073@boulder.Colorado.EDU> feldman@spiff.Tymnet.COM (Steve Feldman) writes:
>We ran into a problem when we tried this a year or two ago.  There is a
>philosophy difference between cisco and Sun on how IP routing over X.25
>should be done.  

There is a freeware implementation of IP over X.25 for Suns. It was
written by 
        Julian Onions (jpo@cs.nott.ac.uk)
        Computer Science Department
        Nottingham University
        Nottingham, NG7 2RD
        ENGLAND

It certainly addresses many of the problems, and you get the source
if you want to do more. Given the unwillingness of the UK to hook
up to the Internet he may not be in a position to make it available
for anonymous ftp [there is an IP/ftp to CB/ftp and/or ftam gateway
somewhere and it would be interesting to know if that extends to
anonymous access and if so how it works]. Anyway if anyone is interested
and Julian Onions authorizes it I will be happy to make the version
I have available for anonymous ftp.

Bob Smart <smart@mel.dit.csiro.au>

Re: Routing thru X.25 from a cisco to a Sun?

#604

Author: Dave Morton
Date: Wed, 29 Aug 1990 09:58

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I think most of Europe (at least Germany at any rate)
use the tunnel software from Julian instead of that from Sun.

Dave Morton,
European Computer Industry Research Centre      Tel. + (49) 89-92699-139
Arabellastr 17, 8000 Munich 81. West Germany.	Fax. + (49) 89-92699-170
E-mail	USA:	dave%ecrc.de@pyramid.com 	EUROPE: dave@ecrc.de

Re: Routing thru X.25 from a cisco to a Sun?

#612

Author: Francis Dupont
Date: Sun, 02 Sep 1990 13:05

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In article <989@ecrc.de>, dave@ecrc.de (Dave Morton) writes:
> I think most of Europe (at least Germany at any rate)
> use the tunnel software from Julian instead of that from Sun.

Now Sun France provides a new IP over X.25 for SunLink 6.0.
The virtual circuit management program is named "x25mgr" (not "x25manager")
and supports :
 * static virtual circuits carrying IP traffic (same than old "x25manager")
 * dynamic virtual circuits carrying IP traffic (new, hardly needed in
France for Transpac, in place of "tunnel software").
 * dynamic virtual circuits carrying IP traffic over DDN network
 * dynamic virtual circuits carrying OSI/CLNP traffic over X.25

For dynamic VC, the interface is not a Point-To-Point interface
and routing implications are well described in docs.
Shutdown after idle time is provided for dynamic VC, etc ...

This is a big improvement of old "x25manager" software.
Sun France gives it to all sites with SunLink (SunNet ?) X.25 6.0 licence,
but I believe it is available in USA.

Francis.Dupont@inria.fr

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