Browse Prior Art Database

Token Ring Local Area Network to X.25 Wide Area Network Gateway

IP.com Disclosure Number: IPCOM000105014D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 8 page(s) / 308K

Publishing Venue

IBM

Related People

Honore, F: AUTHOR [+3]

Abstract

Disclosed is a description of a Token-Ring Local Area Network (LAN) to X.25 Wide Area Network (WAN) Gateway that solves the problem of:

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 21% of the total text.

Token Ring Local Area Network to X.25 Wide Area Network Gateway

      Disclosed is a description of a Token-Ring Local Area Network
(LAN) to X.25 Wide Area Network (WAN) Gateway that solves the problem
of:

o   providing transparent X.25 network access to a large number of
    Token-Ring attached devices

o   providing transparent Token-Ring access to a large number of X.25
    attached devices

o   the incompatibility of the connection establishment response time
    requirements of X.25 and Token-Ring protocols

o   Token-Ring DLC management through a novel use of Token-Ring
    bridges

o   allowing anonymous sources to connect to explicit destinations

o   restarting a X.25 connection after a transient X.25 network
    problem

o   handling devices that are not capable of initiating or re-estab
    lishing connections and

o   minimizing X.25 network costs

      For connections initiated by a Token-Ring device, transparent
ac cess is accomplished by the assignment of Token-Ring addresses and
X.25 parameters to X.25 devices and a 'call back' mechanism to allow
for the timing differences required by Token-Ring and X.25 protocols.

      For connections initiated by a X.25 device, transparent access
is accomplished by the assignment of connection identifiers to
Token-Ring devices.

      The recognition and handling of a large number of Token-Ring ad
dresses is accomplished through a novel use of an internal Token-Ring
bridge which involves a retransmission of frames back to the
Token-Ring so as to make use of the otherwise inaccessible IEEE 802.2
DLC code on the Token-Ring adapter.

      The Token-Ring LAN to X.25 WAN Gateway (embodiment of this
disclo sure) serves to allow System Network Architecture (SNA)
Physical Unit (PU) 2.0 devices to communicate with PU 4 boundary
functions.  This is independent of whether the PU 2 is attached to
the Token-Ring or at tached to the X.25 Packet-switched Data network.

      There are two types of connections the PU 2 device can have
with the Roken-Ring LAN to X.25 WAN Gateway.  Qualified Logical Link
Control (QLLC) Secondary and Primary protocol conversion.

      Transparent access is provided to attaching devices by the
mapping of Token-Ring addresses to X.25 addresses and vice versa.

Through 3174 device definition, each

o   Token-Ring device's real address gets assigned to a Short
    IDentifier (SID)
o   X.25 device gets assigned a unique Locally Administered Address
    (LAA) for its Token-Ring id and also gets a SID.

      When the Token-Ring device wishes to connect with the X.25
device it uses the assigned Token-Ring address as the destination.
The destina tion address will allow Token-Ring LAN to X.25 WAN
Gateway microcode to determine what X.25 number to call and what
parameters to put into the Call Packet.

      Also, when the X.25 device wishes to connect with a Token-Ring
device, a Call Packet is built which con...