RFC 1086 (rfc1086) - Page 1 of 9
ISO-TP0 bridge between TCP and X
Alternative Format: Original Text Document
Network Working Group J. Onions
Request for Comments: 1086 Nottingham
M. Rose
TWG
December 1988
ISO-TP0 bridge between TCP and X.25
Status of this Memo
This memo proposes a standard for the Internet community. Hosts on
the Internet that choose to implement ISO TP0 transport connectivity
between TCP and X.25 based hosts are expected to experiment with this
proposal. TCP port 146 is reserved for this proposal. Distribution
of this memo is unlimited and comments are highly encouraged.
Introduction
This memo specifies a protocol that is used to bridge ISO TP0 packets
between X.25 and TCP networks. This technique is useful when
interconnecting a DDN IP internet to an X.25 subnetwork. This is not
a "magic bullet" solution to the DDN/ISO interoperability problem.
Rather, if one is running higher-layer ISO protocols in both networks
(namely ISO TP0), then a TP0 bridge can be used to achieve
connectivity.
The protocol itself is fairly simple as the method of operation for
running TP0 over the TCP and X.25 protocols have previously been
defined. A bridge offering ISO-TP0 gateway services simply applies
both methods as appropriate. The protocol works by TP0/TCP hosts
"registering" an X.25 subaddress (and corresponding TCP port/IP
address) with the bridge. TP0/X.25 hosts use the standard method for
establishing, maintaining, and releasing connections. When a
connection is established, the bridge establishes the corresponding
TCP connection and simply shuffles TP0 packets between the two. When
a TP0/TCP host initiates a connection, it establishes a TCP
connection to the bridge using port number 146 and communicates the
desired X.25 address. The bridge establishes a connection to the
native X.25 host and simply shuffles TP0 packets between the two.
1. Introduction and Motivation
The migratory protocol described in [RFC 1006] makes possible the
transmission of TP0 packets between hosts on TCP/IP internets. With
the addition of a small protocol converter, a TCP/IP host can be made
to appear in the X.25 addressing space and be able to accept and make
Onions & Rose