X.25 Switch for Linux

The FarSync X.25 Switch allows a Linux based system to act as an X.25 switch with XOT support whilst also supporting all the standard functions available with Linux. The FarSync X25 cards used by the Switch daemon can also with used by other applications simultaneously.

Overview

The FarSync Switch daemon can support up to 500 simultaneous connections from 1 to 16 or more X.25 and XOT (X.25 over IP) ports. The port limit is only restricted by the number of free PCI slots available to install X.25 cards. For the XOT connections the FarSync X.25 High Capacity Pack is required to be installed.

1, 2 and 4 port X.25 cards are available. For most small servers a typical maximum is 16 lines. The network connections using the FarSync X25 cards can be a mixture of RS232C, X.21, V.35, EIA530, RS449 with a maximum line speed of 2 Mbits/s per port. Ports are configurable for both DCE and DTE operation, clock generation can be internal or external.

Routing for the X.25 connections is controlled using the standard Linux route commands. Connections and disconnections of X.25 calls are logged to a daily rotating log file.

The FarSync X.25 Switch software for Linux is provided as a free of charge downloadable application for purchasers of the FarSync X.25 range of products.

Typical Uses

• X.25 concentrator to connect several X.25 devices to an external network
• Routing of data between X.25 and XOT
• Low cost X.25 switch for systems testing

Configuration

The X.25 Switch daemon is very simple to use and configure. the configuration commands are all in the command line, options include:

+t<trace level> set the trace level
-z<message size> set the size of the message buffer to use in a call to the receive function

Routing

The standard Linux routing table is used to route X.25 calls through the Switch. The routing table can contain routes for all sorts of protocols, not just X.25. Routes for the X.25 Switch Daemon are added as follows:

route add -Ax25 1234 fsxsk0
route add -Ax25 5678 x25tap0

Logging

The X.25 Switch daemon writes to a log file, X25Switch, a new log file is created for each day. The previous days log file is renamed to x25Switch.xxx, where xxx is first three letters of the day of the week. This schema provides for a log file for the current day, plus a log file for each day of the week. The log file contents will depend on the level of trace set when the daemon is started.

Example log entries for when a new call is switched.
Wed Feb 4 09:02:01 2004 : Incoming X.25 call from Null NUA to 123, adapter=0, line=0, socket=5
Wed Feb 4 09:02:01 2004 : Connecting to 123
Wed Feb 4 09:02:01 2004 : Call routed: Null NUA to 123, adapter=255, line=255, socket=6

Example log entries for when a call is terminated.
Wed Feb 4 09:42:05 2004 : Zero length Rx Data - socket=6, cause=0x00, diag=0x00
Wed Feb 4 09:42:05 2004 : Connection closed, sockets 5 & 6, cause=0x00, diag=0x00

Systems Requirements

The X.25 Switch daemon requires the FarSync X.25 driver version 2.0 or later. The switch will run on 2.2.x, 2.4.x and 2.6.x Kernels, see the FarSync X.25 driver Readme file for further details of specific Kernel versions. For XOT support the FarSync X.25 High Capacity Pack version 1.02 and above must be used.

Technical Specifications
Product Name	FarSync X.25 Switch for Linux
Product code	FS9601
Switch Features
Maximum through connections	500
Connection types supported	SVC
Maximum X.25 ports	No limit, dependent on the number of FarSync X.25 cards installed
Logging	Optional logging of X.25 call connections and disconnections. daily rotating log file
Data packet size range	0 to 4096 bytes
Routing	Routes configured using Linux standard route command
Kernel versions supported	2.2.x, 2.4.x and 2.6.x
FarSync X.25 Features(using the FarSync X25 T-Series cards)
DTE/DCE Operation	Both
Line clocking	Both Internal and External
Lines per card	From 1 to 4 X.25 lines per card, cards per server only limited by available PCI slots
Line Interfaces	RS232C, X.21, V.35, EIA530, RS449 - 2 Mbits/s per line maximum
Maximum SVCs (all types)	254 per card using the standard FarSync X25 T-Series cards 4095 per line using the FarSync X.25 High Capacity Pack
XOT (IP over x.25)	Supported and accessible by the FarSync X.25 Switch when installed in conjunction with the FarSync X.25 High Capacity Pack version 1.02 and above
Data Packet size range	16 to 4096 bytes
Reverse Charging option	Yes
Closed User Group (CUG) option	Yes
Network User Identifier (NUI)	Yes
Fast Select	Yes
Packet & Window size negotiation	Yes
Throughput class negotiation	Yes
Extended sequence numbering (128)	Yes

Download X.25 Switch

The X.25 Switch daemon software can be download from here.
Remember you will need to install FarSync X25 T-Series cards to use the product.

Information in this document is subject to change without notice.
Other products and companies referred to herein are trademarks or registered trademarks of their respective companies or mark holders

Last updated: 22-Jul-2005