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From: satz@cisco.com (Greg Satz)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: x25-->Cisco-->VAX(PSI) Configuration Possible?
Message-ID: <25606@boulder.Colorado.EDU>
Date: 4 Sep 90 06:46:46 GMT
Sender: news@boulder.Colorado.EDU
Lines: 38

>>      9.6 x25 (Public-PSS)            |
>>       ----------------------|Cisco|  |
>>                             |     |--|---|VAX with PSI Software|
>>                             |AGS2 |  |
>>       ----------------------|     |  |
>>       64k Leased Line

Yes, the cisco software can be made to do this but it requires the
following changes to your topology.

                                     LAN
      9.6 x25 (Public-PSS)            |
       ----------------------|Cisco|  |   |
                             |     |--|---|VAX with PSI Software|
                             |AGS2 |  |   |
       ----------------------|     |______|
       64k Leased Line               X.25

This solution utilizes the X.25 switching functionality to switch PSI calls
from the PSS through the cisco and into the VAX. It also requires that the
Vax act as a router from its X.25 interface to its ethernet. Incoming Call
Requests will be forwarded from the cisco to the Vax. The Vax will extract
the DECNET packets from the established VC and forwarded it back to the
cisco for further forwarding down the 64K leased line.

This requires that you get an extra serial interface running X.25 to
connect up the Vax.

The drawback to this is the extra serial interface and the extra hop across
the serial interface and ethernet. The extra hop can be overlooked if you
are using 9.6 serial X.25 lines on the PSS as this is slow enough that the
extra two hops won't be noticed. This also assumes you can control the
demands on the Vax system resources.

The advantage is that this solution will work in today's shipping software.

Greg Satz
cisco