Browse Prior Art Database

Frame Relay Direct Connection without a Frame Relay Network

IP.com Disclosure Number: IPCOM000111522D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 140K

Publishing Venue

IBM

Related People

Aho, ME: AUTHOR [+5]

Abstract

Disclosed is a method for using the frame relay interfaces and protocol in a direct point-to-point connection (without going through a frame relay network).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Frame Relay Direct Connection without a Frame Relay Network

      Disclosed is a method for using the frame relay interfaces and
protocol in a direct point-to-point connection (without going through
a frame relay network).

      This can be a local connection (connect 2 systems back-to-back)
or a high speed point-to-point communications network (such as T1).

      The advantages of the interfaces are higher speed and better
reliability.  The advantages of the protocol are the connectivity (to
any system that supports frame relay), full duplex (send and receive
data simultaneously), and data integrity (error detection and error
recovery).

Following is a definition of terms listing:

o   FH - Frame Handler - The network or provider of the frame relay
    service.

o   TE - Terminal Equipment - The attaching terminal/system or the
    user of the frame relay service.

o   T391 - Timer (normally 10 seconds) - Timer used to measure how
    long to wait for LMI messages or when to send another LMI
    message.

o   N391 - Counter (normally 6) - Counter used to determine the
    frequency of a LMI full status exchange.  It is also used to
    determine how often to retry or wait for an LMI exchange for
    error recovery.

o   LMI - Local Management Interface - The interface used to exchange
    status between the TE and FH.

o   DLCI - Data Link Connection Identifier - Identifies the logical
    connection.

o   T1 - A high-speed digital service (tariff) operating at 1.544M
    bps.

FRAME RELAY OPERATION - In a normal frame relay environment, the
TE(s) are connected through a frame relay network (FH).  The
connection to the remote TE is identified by a DLCI.  This is
reflected in Fig. 1.

      There is an LMI exchange between the TE and FH to determine the
state/status of the TE/FH connection and of the DLCI(s) or the
connections to the remote TE(s).  The TE sends Status_enquiry
messages to the FH every T391.  Every N391 Status_enquiries a full
status is requested from the FH.  The FH responds to a Status_enquiry
for a full status with the state/status (present, active, etc.) for
each DLCI or connection to a remote TE.  The other Status_enquiries
(not full status) are keep-alive exchanges between the TE and FH.
The successful exchange of Status_enquiry messages between the TE and
FH is used to verify the physical connection between the TE and FH.
The state/status for each DLCI is used to verify the connection to
the remote system/station.

      Data can be exchanged when the state/status for the DLCI is
active.  Data can not be exchanged when the state/status for the DLCI
is not active.

TE MODE OF OPERATION - For TE mode of operation, the LMI exchange is
started when the Network description (the line or physical interface)
is varied on.

      The N391 and T391 will be used to control and monitor the
Status_enquiry exchange.  If the initial Status_enquiry exchange is
not su...