TCP to X.25 POS Gateway Appliance for APACS, ISO 8583 and many custom ePOS Transactions

The FarLinX TCP-X25 POS Gateway datasheet may be downloaded here (pdf)

Overview

Some modern Point-Of-Sale (POS) terminals, store controllers and other types of electronic money transfer processing equipment connect via TCP/IP whilst many existing POS transaction processing Hosts, such as VISA, have X.25 interfaces. Similarly in some cases the reverse situation exists. Standard TCP to X.25 Routers can break the POS protocols and do not provide the specialist translation required. The FarLinX TCP-X25 POS Gateway has been specifically designed to overcome this problem and provide a dependable means of inter-connecting POS equipment to electronic money transfer central processing systems where TCP/IP and X.25 networks are in use.

The very versatile FarLinX Gateway supports ISO 8583, APACS, HGEPOS plus CTL (Card Tech Ltd) Online message type support. There are 3 versions providing scalable solutions, starting with a small scale single store version supporting up to 10 simultaneous transactions to the MAX version allowing up to 4,000 simultaneous transactions.

In addition the Gateway can be configured for general purpose TCP to X.25 data translation with flexible routing options. Many customers purchase the product for these functions alone. Support is provided for fixed routes, dynamic routing, Cisco RBP compatibility and RFC1006 support.

Two Gateways can be used in a load balanced, resilient configuration that has no single point of failure.

The FarLinX TCP-X25 POS Gateway will operate in conjunction with an IP dial platform to support remote POS terminals connected via PSTN or ISDN connections.

The Gateway is designed for non-stop operation. Almost all changes to the configuration are applied dynamically with no need for restarting.

Where a software solution that can be installed on PC Servers running Windows is preferred the FarSync TCP-X25 POS Gateway in-conjunction with FarSync X.25 cards should be used.

Example Applications

• Interconnection of X.25 POS Terminals to TCP/IP connected host/s
• Interconnection of TCP/IP connected POS Terminals to X.25 connected host/s
• TCP to X.25 support for EFT (Electronic Funds Transfer), Payment Clearing and Electronic Payment
• General purpose Gateway to interconnect TCP/IP and X.25 networks

POS Gateway Operation

Typical network configuration using the FarLinX TCP-X25 POS Gateway

The Gateway provides connection establishment and data packetisation services for APACS, ISO 8583, HGEPOS and other systems to allow POS terminals operating over TCP/IP to interface to X.25 connected hosts, flexible general purpose options for mapping and routing TCP to X.25 data are also provided.

A special configuration option is available to support connection to CTL (Card Tech Ltd) Host equipment where the POS terminals are connected by X.25 and the connection to the verifying host is by TCP/IP.

The Gateway provides routing facilities to select the appropriate Host from those available and maintains X.25 sessions to the Host as required. An X.25 session is established for the POS transaction when the TCP session for a transaction is established.

The Gateway can operate in conjunction with an IP dial-up platform device supporting autocommand telnet this permits support for remote POS terminals connected via PSTN or ISDN connections.

APACS Options

APACS connections over X.25 can operate in 2 different ways, TPAD-HOST Mode and T/T-TPAD Mode. The FarLinX TCP-X25 POS
Gateway supports both modes and also transparent conversion between the modes.

TPAD-HOST Mode

APACS messages are sent without a LRC in TPAD-HOST mode, no APACS control frames eg ACK, DLE EOT are required. The transaction consists of a pair of APACS messages. An X.25 virtual circuit is established by the Gateway at the start of each transaction and cleared by the Gateway at the end of the transaction.

T/T-TPAD Mode

APACS messages are sent complete with the LRC. APACS control frames are used to regulate the flow and termination of the APACS message, each message being acknowledged with an ACK frame. An X.25 virtual circuit is established by the Gateway at the start of each transaction and cleared by the Gateway at the end of the transaction.

HPAD Conversion

APACS messages on the Host side are handled complete with LRC and control frames to acknowledge and regulate the flow. The messages are extracted and handled on the POS Terminal side as simple messages without the LRC and transmitted without the use of control frames. This provides conversion from TPAD-Host mode on the terminal side to T/T-TPAD mode on the Host side.

TPAD Conversion

APACS messages on the Terminal side are handled complete with LRC and control frames to acknowledge and regulate the flow. The messages are extracted and handled on the Host side as simple messages without the LRC and transmitted without the use of control frames. This provides conversion from T/T-TPAD mode on the terminal side to TPAD-Host mode on the Host side.

General Purpose Options

The POS Gateway can support a wide range of TCP to X.25 data translation and connection functions, including fixed and dynamic
routing, RFC1006 support and Cisco RBP compatibility. The different modes of operation can be configured on a per connection basis.

Overview of Resilient Operation

The FarLinX TCP-X25 POS Gateway can be deployed in a wide variety of ways to achieve the level of resilience required by the application. The level will depend on the value of the data traffic and the acceptable degree of user intervention required to rectify any problem. The aim with resilience is to remove single points of failure. Resilient configurations using more than one POS Gateway also allow improved performance by sharing the traffic load between several machines.

Network Line Redundancy

To achieve network line redundancy, a single FarLinX TCP-X25 POS Gateway may operate with two or more X.25 lines. It can route data over any active line connected to the Gateway so that if one line goes out of operation then the other lines continue to be used automatically.

Gateway Redundancy and Load Balancing

For fully resilient operation, two (or more) FarLinX TCP-X25 POS Gateways may be deployed. They can be either configured for simple failover from a primary to a backup machine or for full load balanced operation. In Network Load Balancing (NLB) mode both failover and load balancing of the ePOS transactions are provided thus ensuring there is no single point of failure and that there is no performance bottleneck.

The built in POS Gateway Supervisor checks the state of the X.25 network lines and as these change state between fully operational and faulty it automatically enables/disables the unit from the pool of FarLinX TCP-X25 POS Gateway's, thus managing the availability of that particular POS Gateway machine. Key events such as the loss of an X.25 line are recorded on a daily rotating event log.

Performance and Expandability

The FarLinX TCP-X25 POS Gateway easily handles very high transaction loads. Support for large numbers of X.25 lines and multiple Gateways provides enormous scalable expansion capability and resiliency. The main performance and expansion features of the Gateway are:

• Up to 500 POS transactions per second on each Gateway (MAX version)
• Multiple load balancing Gateways, up to 32 sharing a single IP address
• X.25 line speeds from 2,400 baud to 8 Mbits/s
• From 1 to 8 X.25 lines per Gateway
• 3 10/100 BaseT LAN ports, RJ45. Each port is for connection to a separate Network
• X.25 network, leased line and X.25 dial up connections supported
• Up to 2,000 connections (SVC and PVC) per X.25 line (MAX version)
• 3 versions - 10 session, 20 session and MAX (up to 4,000 sessions)

Connection Routing and Address Mapping

The FarLinX TCP-X25 POS Gateway is typically used to route connections to a single acquiring host. It can, however, support routes to 2,000 different X.25 hosts. Similarly, when using the called X.25 address as the routing key, incoming X.25 calls can be routed to thousands of different TCP/IP hosts.

When making connections to the X.25 network, the POS Gateway has the capability of mapping the source IP address to a calling X.25 address, thus allowing the destination X.25 host to identify the connection source uniquely.

The Dynamic routing option allows the X.25 address (NUA) and call parameters to be set by the remote application at the time each X.25 connection is established. X.25 packetisation information is passed to the application.

Configuration Application   The remotely accessible Configuration Application for the POS Gateway allows the TCP interface, X.25 connection, and POS protocol types and the event log levels to be selected. Almost all changes to the configuration are made dynamically so continuous operation of the Gateway can be maintained. The sample screen shot was taken from the Configuration Application, it shows the configuration parameters for an APACS 30 X.25 to TCP/IP connection. Configuration by Text Files As an alternative to using the Gateway Configuration program, the POS Gateway configuration can be defined in text files. This approach is very scalable, allowing hundreds of routing definitions to be easily configured. As with the Configuration Application changes to the text files can be applied dynamically allowing continuous operation to be maintained. Maintenance Contract FarSite recognises that this product is often used as a key component in POS transaction systems and as such a guaranteed response to unexpected problems is required. A maintenance contract is available for the FarLinX TCP-X25 POS Gateway for priority service and rapid problem resolution.

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: 18-Mar-2009