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Establishing Switched Virtual Circuit Connections Between X.25 DTEs in the Event of Call Collisions

IP.com Disclosure Number: IPCOM000100693D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Geise, DM: AUTHOR [+2]

Abstract

A method is disclosed which guarantees that two X.25 DTEs will establish a single Switched Virtual Circuit (SVC) connection between themselves even if their calls collide.

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This is the abbreviated version, containing approximately 76% of the total text.

Establishing Switched Virtual Circuit Connections Between X.25 DTEs in the Event of Call Collisions

       A method is disclosed which guarantees that two X.25 DTEs
will establish a single Switched Virtual Circuit (SVC) connection
between themselves even if their calls collide.

      Call collisions occur when two X.25 DTEs attempt to call each
other at approximately the same time and both receive an incoming
call packet from the DTE to which they have a call pending.  If both
incoming calls are accepted, the two DTEs will be connected with two
SVCs.  If both incoming calls are cleared, the two DTEs will not be
connected at all.  Both of these solutions are undesirable.

      However, if one of the DTEs is configured to retry a call in
the event of a call collision (and the other DTE is configured NOT to
retry), a single SVC will connect the two DTEs.

      The "retry on call collision" option is specifiable for each
remote DTE that a local DTE is configured to communicate with.

      Mechanism: In the following discussion, the DTE configured to
retry its call request is called DTE 1, and the DTE configured not to
retry is called DTE 2.  The call sent by DTE 1 is called CALL 1,
and the call sent by DTE 2 is called CALL 2.  Both DTEs generate
their respective calls at about the same time.

      If DTE 1 receives CALL 2 after it sends CALL 1, it "ignores"
CALL 2.  That is, DTE 1 does not accept CALL 2, and thereby allows
CALL 2 to "time out...