Ref: 10630010
Title: GS/X.25-IP Virtual Circuit Assignment and Limitations
Date: 11/29/90

Copyright 3Com Corporation, 1991.  All rights reserved.

This topic explains how the 128 virtual circuits available on
the GS/X.25-IP gateway can be allocated.

The gateway has two functions in which virtual circuits are allocated:
Connection Service and Routing.  Connection Service maps one virtual circuit
for each incoming or outgoing X.25 Incoming Call or X.25 Call Request.  The
number of users that issue Connection Service calls is limited to the number
of ports that are available.  The GS/X.25-IP has 48 ports available.  Thus,
if all 48 ports are to be defined for Connection Service, then 48 virtual
circuits must be available to allow all ports to be active at the same time.

When defining the routing function, there is a default limit of four virtual
circuits per remote network.  If 20 remote networks are defined with four
virtual circuits per remote network, 80 virtual circuits are required.  If you
add the 80 virtual circuits to the 48 used for connection service, this
would result in a total of 128 virtual circuits.

If only routing is to be supported, then the limitation of 128 virtual
circuits is based upon the combination of the defined virtual circuits per
remote network, multiplied by the number of remote networks defined.  The
specification of virtual circuits per remote network is defined using the
command:  "Setd LCNperRemnet = {1-128}".

The number of virtual circuits assigned for connection service use is based
on the number virtual ports assigned to a line and the number of virtual
circuits assigned to that line.  Virtual port assignment is defined using
the command:

   Setd Line <line number> PortNumber {=![<portid>[-!<portid>,...]|ALL]}

The number of virtual circuits assigned to a line must take into account the
total number of virtual circuits to be dedicated to routing on a particular
line plus the number of virtual ports assigned to that line.  The number of
virtual circuits dedicated to a line is defined using the command:

   Setd Line <line number> NumberLCN={1-128}

