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TCP And UDP Over IPX Networks With Fixed Path MTU (RFC1791)

IP.com Disclosure Number: IPCOM000004045D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 8 page(s) / 20K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

T. Sung: AUTHOR

Abstract

Most of network applications run on some sort of transports. And, if one is to let such applications to run over a foreign network protocol, the simplest way would be to allow the applications' transports to run over that network protocol. For TCP/IP applications, that transport is TCP or UDP. Hence, to let TCP/IP applications run over IPX, we would need to have TCP and UDP run over IPX. And, once TCP and UDP are allowed to run over IPX, all TCP and UDP based applications, such as HTTP for WWW, or NFS, can easily be made to work over IPX networks.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 14% of the total text.

Network Working Group T. Sung

Request for Comments: 1791 Novell, Inc.

Category: Experimental April 1995

TCP And UDP Over IPX Networks With Fixed Path MTU

Status of this Memo

This document defines an Experimental Protocol for the Internet

community. This does not specify an Internet standard of any kind.

Discussion and suggestions for improvement are requested.

Distribution of this memo is unlimited.

IESG Note:

Internet Engineering Steering Group comment from the Area Director

for Transport Services: Please note well that this memo is an

individual product of the author. Implementation experience,

particularly on the effectiveness of the protocols in dual-stack

environments, is needed.

1. Introduction

Most of network applications run on some sort of transports. And, if

one is to let such applications to run over a foreign network

protocol, the simplest way would be to allow the applications'

transports to run over that network protocol. For TCP/IP

applications, that transport is TCP or UDP. Hence, to let TCP/IP

applications run over IPX, we would need to have TCP and UDP run

over IPX. And, once TCP and UDP are allowed to run over IPX, all TCP

and UDP based applications, such as HTTP for WWW, or NFS, can easily

be made to work over IPX networks.

DLsw is another example of such applications. As it is a TCP

application (and TCP requires IP), the administrator is forced to run

IP on his network in order to support DLsw. If the site was an IPX

shop, it means that he now must manage IP protocol/addresses in

addition to IPX. If TCP could be made to run on IPX, then he would

not have to add IP to his repertoire of network protocols to manage.

TCP/IPX allows TCP/IP applications to run over IPX networks by

letting TCP and UDP run over IPX. And this memo specifies the packet

format and operational procedures for running TCP and UDP over IPX.

2. Running UDP Over IPX

Since UDP datagrams can be up to 64K octets long, and the size of IPX

packet is limited to that of the path MTU, large UDP datagrams must

be fragmented. And, since IPX does not support fragmentation, large

UDP datagrams must be fragmented before they are passed to IPX. For

that purpose, a new protocol called IPXF (IPX Fragmentation layer),

is invented. UDP must run on IPXF rather than directly on IPX. IPXF

layer is described in section 4.

To IPXF service users, IPXF behaves just like IPX except that IPXF

accepts datagram larger than the IPX path MTU. As such, we describe

UDP in this section as if it is running on IPX.

UDP must send and receive the packets on IPX/IPXF socket 0x9092.

Though it may be possible to send a packet from sockets other than

0x9092, such sockets cannot receive UDP datagram destined to a well

known socket 0x9092. Hence, the bidirectional communcation may not

...