Microtronix Datacom Access 4000 X.25-TCP/IP Gateway X.25 Network Migration for Telecom Applications

Issued: June 17, 2010 Prepared by: Vic Phillips Senior Datacom Engineer [email protected]

North America: London, ON CANADA Tel: +1 519 690-0091

Europe: Oosterhout, The Netherlands +31 162 714017

Latin America: Vitoria, ES Brasil +55 27 9941 9595

San Jose, CA USA +1 888 690-0091

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Disclaimer The information contained in this document represents the current view of Microtronix on the issues discussed as of the date of publication. Because Microtronix must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microtronix, and Microtronix cannot guarantee the accuracy of any information presented after the date of publication. This white paper is for informational purposes only. Microtronix MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT. Complying with all applicable copyright laws is the responsibility of the user. Without limiting the rights under copyright, no part of this document may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise), or for any purpose, without the express written permission of Microtronix. Microtronix may have patents, patent applications, trademarks, copyrights or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microtronix, the furnishing of this document does not give you any license to these patents, trademarks, copyrights or other intellectual property. © 2010 Microtronix Datacom Ltd. All rights reserved.

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About Microtronix Datacom Ltd. For 30 years, Microtronix has been a world leader in providing international Telcos and Telecoms with hardware and software development in migrating from X.25 to TCP/IP networks. As a pioneer in data communications, Microtronix has an exceptional reputation for quality, product support, customer specific software development and on time deliverables. With response teams in Brazil, Canada, The Netherlands and the United States, Microtronix can respond to our customers’ every needs. Our customer base spans 43 countries and includes national, international and regional Telcos. Among our successes:

Microtronix is an employee owned private corporation with holdings in Digital Media, FPGAs and an Embedded Engineering group.

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Table of Contents Overview ...................................................................................................................................... 1
 Key Features ............................................................................................................................... 2
 X.25-TCP/IP Gateway........................................................................................................... 2
 X.28/Serial – TCP/IP............................................................................................................. 2
 Ethernet/IP Network.............................................................................................................. 2
 CDR Collection Option.......................................................................................................... 2
 System and Management ..................................................................................................... 2
 Interfaces ..................................................................................................................................... 3
 WAN Port .............................................................................................................................. 3
 Serial Port (Console)............................................................................................................. 3
 Ethernet Port......................................................................................................................... 3
 USB Host Port for additional devices .................................................................................... 3
 Power Connections............................................................................................................... 3
 X.25 to TCP/IP Migrations .......................................................................................................... 4
 Legacy X.25 Network............................................................................................................ 4
 X.25 Network Replacement .................................................................................................. 4
 Conversion of X.25 Server to TCP/IP; X.25 Network Maintained ........................................ 5
 Conversion of X.25 Server to TCP/IP; X.25 Network Replaced .......................................... 5
 Migration Methods ...................................................................................................................... 7
 X.25 Encapsulation ................................................................................................................... 7
 XOT – X.25 over TCP (RFC 1613) ....................................................................................... 7
 X.25 Data Encapsulation ...................................................................................................... 7
 XOT – Server support ........................................................................................................... 7
 X.25 to TCP Conversion ........................................................................................................... 8
 Data Only Conversion........................................................................................................... 8
 Message Preservation .......................................................................................................... 8
 Telecom Applications............................................................................................................... 10
 CDR Collection ....................................................................................................................... 10
 X.25 Network Replacement ................................................................................................ 10
 Conversion of CDR Collector to TCP/IP ............................................................................. 11
 Local (Distributed) CDR Collection ..................................................................................... 12
 Operations and Alarms ........................................................................................................... 13
 X.25 Network Replacement ................................................................................................ 13
 Conversion of Operations Server to TCP/IP ....................................................................... 14
 Example Network Migration .................................................................................................... 15
 Specifications ........................................................................................................................... 16
 Software and Protocols........................................................................................................... 16
 X.25 Features ..................................................................................................................... 16
 X.25 / TCP Encapsulation and Conversion methods.......................................................... 16
 X.25 to TCP Connection Mapping and Address Translation .............................................. 16
 TCP to X.25 Connection Mapping and Address Translation .............................................. 16
 X.28/Serial Features ........................................................................................................... 17
 System Services ................................................................................................................. 17
 CDR Collection Option........................................................................................................ 17
 Hardware ................................................................................................................................ 18
 Power Requirements .......................................................................................................... 18
 Environmental Specifications .............................................................................................. 18
 Regulatory Compliances..................................................................................................... 18
 Mechanical.......................................................................................................................... 18


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Overview The Access 4000 X.25 - TCP/IP Gateway provides for the migration of X.25 to TCP/IP. X.25 logical channels are mapped to TCP/IP sockets using a comprehensive routing and address translation table that allows for full control of connection recognition and setup. Several message encapsulation methods are supported for preservation of messages to suit a variety of applications. An easy to use, intuitive, web-based configuration and monitoring server is built in, requiring only a standard internet browser. Context-sensitive help is available for all parameter settings.

The Access Gateway provides a flexible and comprehensive X.25 to TCP network migration solution, supporting X.25 to TCP conversion and X.25 over TCP encapsulation. This makes it the ideal tool for converting Telecom X.25 applications to IP networking and IP-based servers. Telecom X.25 Application conversion includes: • • •

CDR/AMA collection Operations management including command line interfaces Alarms

The Access Gateway X.25 interface is compatible with: • • •

All switch types including Lucent, Ericsson, Alcatel, Nortel, Siemens, etc Legacy X.25-based server platforms X.25 network equipment (modems, X.25 switches)

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Key Features X.25-TCP/IP Gateway •

Connectivity between X.25 and TCP/IP devices: o o o o

• •

XOT – RFC 1613: X.25 over TCP Encapsulation X.25/TCP Conversion X.25 Message Preservation/Encapsulation X.29 (PAD) support

Address matching/translation table providing connectivity for large networks Complete transparency to the X.25 devices

X.28/Serial – TCP/IP •

Connectivity between serial/X.28 and TCP/IP devices

Ethernet/IP Network The Linux 2.6 kernel provides complete and robust network protocol suite support including: • • • •

Ethernet 802.1Q Virtual LAN (VLAN) IPv4 (optional IPv6) TCP/UDP

CDR Collection Option The CDR Collection option may be added to the basic Gateway to provide local collection of Call Detail Records • • • • • •

Direct X.25 connection to switch (eliminates modem) Collection protocols: AMATPS (BX.25), XFER, MTP, FTAM Local storage of CDR/AMA files on removable media FTP/IP push files directly to billing server Definable automatic polling schedule and manual poll Allows other simultaneous X.25/TCP connections on same interface

System and Management Industry standard system and management applications including: • • • • • • •

SYSLOG with logging to remote server SSH and Telnet remote management SNMP system MIB for polling, and link alarms Interface tracing using tcpdump HTTPS web-based browser configuration interface with context-sensitive help FTP, DNS, DHCP, NTP, SCP, RADIUS Real time statistics of line performance, errors, connections etc.

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Interfaces

WAN Port • • • • •

DB25/DCE - RS530 Software selectable interface type: RS530(a), RS232/V.24, V.35, X.21, RS449 Clocking options: internal (DCE), external (DTE or DTE emulation), split, custom X.25 or X.28/serial operation Asynchronous speeds to 115200bps, synchronous to 2mbps

Serial Port (Console) • • • •

DB9/DCE - RS232 / EIA-574 Clocking options: internal (DCE), external (DTE or DTE emulation), split, custom X.25 or X.28/serial operation Asynchronous speeds to 115200bps, synchronous to 128kbps

Ethernet Port • • • •

RJ45 - 10/100Base-T Multiple VLAN definitions IPv4, IPv6 (available option) Static or dynamic IP assignment

USB Host Port for additional devices • • •

Mass storage Serial Ethernet

Power Connections The Access 4000 comes in 2 models: • •

120/240V AC using a 12VDC adapter -48VDC power supply

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X.25 to TCP/IP Migrations Legacy X.25 Network The following diagram shows a typical legacy X.25 network with X.25 based application servers and telephone exchanges (CO switches) with X.25 interfaces. The devices may be connected directly to the X.25 switching equipment or via a modem.

X.25 Network Replacement When the legacy servers and exchanges are maintained, and just the X.25 network is replaced, each exchange and the server require an X.25-TCP/IP Gateway connected to a shared IP network. The Gateway replaces any modem.

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When the server or exchange initiates an X.25 connection, the X.121 address that was previously routed by the X.25 network is replaced with an X.121 to TCP/IP address translation map in the Gateway. An X.25-TCP conversion method is used that preserves the application protocol messages. XOT tunnelling works in most cases, but a more efficient data-only encapsulation method is recommended. Either method can be configured in the Gateways to be transparent to the servers and exchanges.

Conversion of X.25 Server to TCP/IP; X.25 Network Maintained When the legacy server is replaced with a TCP/IP server, and the original X.25 network is maintained, then the X.25-TCP Gateway connects between the X.25 network and the server. Address translation depends on how the server handles the application protocol. If the server implements an XOT driver, then it establishes on XOT connection to the Gateway, and delivers the X.121 address of the exchange over that tunnel. This is forwarded transparently by the Gateway to the X.25 network for routing. If the exchange initiates a connection, the Gateway translates the X.121 address to the IP address of the server to create an XOT tunnel, and forwards the X.25 call over the tunnel. If the server implements an encapsulation protocol like RFC 1006, then it uses a unique TCP/IP address for each exchange, and the Gateway uses its TCP/IP to X.121 translation map to generate the X.25 connection. In a large network, multiple IP addresses assigned to the gateway is impractical, so an assignment of unique TCP port numbers would be used. If there is more than one X.25 network interface, multiple gateways would share the load. The Gateway supports multiple simultaneous connections.

Conversion of X.25 Server to TCP/IP; X.25 Network Replaced When the application server is replaced with a TCP/IP server, and the X.25 network eliminated, each exchange requires an X.25-TCP/IP Gateway connected to a shared IP network. Address translation depends on how the server handles the application protocol.

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If the server implements an XOT driver, then it establishes on XOT connection using the TCP/IP address of the Gateway connected to the exchange, and delivers the X.121 address of the exchange over that tunnel. This is forwarded transparently by the Gateway to the X.25 interface to the exchange. If the server implements an encapsulation protocol like RFC 1006, then it uses a unique TCP/IP address for each exchange, and the Gateway uses its TCP/IP to X.121 translation map to generate the X.25 connection. Typically the same TCP port number would be used as each gateway will have a unique IP address.

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Migration Methods X.25 Encapsulation Encapsulation is used when the X.25 network between the servers and exchanges is being replaced with an IP based network and the X.25 devices are to continue to operate unchanged. An X.25-TCP Gateway is required at each server and exchange, replacing the X.25 network address routing via the X.25-TCP/IP address mapping and translation table.

XOT – X.25 over TCP (RFC 1613) X.25 virtual circuits can be tunneled over a TCP/IP network using the XOT protocol (RFC 1613). By tunneling the X.25 protocol over TCP, the Gateway allows for seamless TCP/IP integration without modification or re-configuration of the server or exchange. All network addressing is preserved. By transporting the packets, the gateway preserves all of the options of the X.25 protocol. This is especially important when the X.25 call request packet contains options that cannot be converted to TCP, or special packets like Q-bit data, reset, and interrupt packets are used by the application.

X.25 Data Encapsulation As an alternative to XOT, X.25 data-only can be encapsulated over a TCP/IP network using a message preservation method. By encapsulating the X.25 data over TCP using a message preservation header, the Gateway allows for message transparency between the X.25 devices. The TCP-X.25 mapping table allows for the recreation of the X.25 network addressing at the receiving end. RFC1006 is the method commonly used for OSI protocols like FTAM, and QMBIT for protocols like MTP that also require X.25 Q-bit packet transparency. This is the preferred method because it significantly reduces network overhead and eliminates possible packet and window size negotiation incompatibility inherent in XOT.

XOT – Server support When the server’s X.25 interface is replaced with an XOT driver, the requirement for an external XOT Gateway is eliminated.

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X.25 to TCP Conversion The X.25 to TCP Conversion Gateway interconnects the X.25 interface of the exchange to TCP/IP servers. The Gateway terminates each protocol stack and interconnects sessions between them. This interconnection may be as simple as data-only transfer, or more complex like “message boundary preservation” for X.25 M-bit packets, and message conversion for packets like interrupt and Q-bit data. These latter methods require modest modification to the TCP/IP application to support the conversion method. Multiple gateway sessions are supported, using both X.25 PVCs and SVCs.

Data Only Conversion These methods require no changes to the X.25 and TCP applications of the end devices. Both are capable of dealing with the data as a stream of bytes. No encapsulation headers are required to preserve message boundaries or type. Servers may use a standard terminal emulator like HyperTerminal to initiate the TCP session via the Gateway to the exchange. The conversion methods supporting byte stream conversion include: •

RAW – Message type or boundaries are not preserved. Data is forwarded as and when received.

•

LINE – Similar to RAW where there is no regard to message boundaries in data transferred from X.25 to TCP. In the TCP to X.25 direction, data characters are buffered until an ASCII CR (carriage return) is encountered and then forwarded to the X.25 interface. Any LF (line feed) characters following a CR are stripped. This is useful when the X.25 host is providing a legacy command line interface that requires this behavior, and an incompatible TCP/IP based terminal emulator is used.

Message Preservation Encapsulations allow messages generated from one side of a gateway connection to be preserved when delivered to the other side. Many applications, particularly legacy X.25-based, require message preservation. The most common method of encapsulation (or preservation) of application messages is the use of the More-bit in X.25 data packet headers to mark the continuation of a message across a series of full data packets. A length header is introduced into the TCP byte stream that specifies

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the amount of data following that comprises the message. The current encapsulation methods supported includes: •

RAW-MBIT - “best-effort” message boundary preservation. Similar to RAW above, a command-response handshake is needed to ensure that multiple messages in the same direction do not get blended into a single TCP packet. An M-bit sequence of X.25 data packets is merged into a single TCP transmission, and a received TCP packet is sent as a single X.25 packet, or an M-bit sequence of packets where the message exceeds the maximum packet size.

•

MBIT – Guaranteed message preservation using X.25 M-bit sequence to TCP length header insertion. The TCP length header is 2 bytes (network order) containing the message length, followed by the message. Any merging or splitting of messages in the TCP byte stream does not impact the message boundaries.

•

RFC1006 – Guaranteed message preservation as with MBIT, but the header is 4 bytes coded as version (03), pad (00) and a 2 byte length field (network order) of the entire message including the header.

•

Q-MBIT – Guaranteed message preservation as with MBIT, but the header is 4 bytes coded as version (03), Q-bit flag (00/01) and a 2 byte length field (network order) of the entire message including the header.

•

Custom – Additional methods can be added on an “as needed” basis. These can include header variations, and in-line character sequences like STX-ETX.

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Telecom Applications CDR Collection Legacy CDR/AMA collection uses an X.25 interface to the exchange. The collector connects to all the exchanges via an X.25 network, or through leased line or dialup modem connections. The collector polls the exchanges for any files, or passively accepts files from the exchange. CDR collectors typically deliver collected files to a billing server or other servers via FTP/IP.

CDR/AMA collectors use protocols like AMATPS, FTAM, MTP, and XFER, and any conversion of X.25 that carries the protocol messages across a TCP/IP network MUST preserve the message boundaries of the protocol. There are a number of conversions that can be implemented.

X.25 Network Replacement When the X.25 network (or network of leased lines or modems) is replaced, each switch and collector X.25 interface is connected to an X.25/TCP gateway.

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Conversion of CDR Collector to TCP/IP When the CDR collector is converted to TCP/IP, and the X.25 network left in place, a centralized conversion of X.25 to TCP is required. The CDR collector should support the switch-specific protocol using an encapsulation method over TCP.

When the X.25 network is also replaced, a Gateway is required at each switch.

The Microtronix AMA Collection Manager is an excellent centralized collector solution to replace the legacy X.25 collection server.

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Local (Distributed) CDR Collection The X.25 network and the legacy CDR collector can both be replaced by an Access 4000 CDR Collection Manager installed at each exchange connected directly to the X.25 interface. The Collection Manager does local polling and storage of the CDR/AMA files. Files are pushed directly to the billing platform, bypassing an intermediate collection server.

This method has the distinct advantage of collecting and storing files even while the IP network or billing server are unavailable, preventing record file overrun on the exchange. It also eliminates the bottleneck and single point of failure of a centralized collection server. Note the simplicity of the solution. It directly converts the switch to an IP-capable collection solution without acquiring an expensive upgrade from the manufacturer, and without touching the switch configuration. Storage capacity on the CDR Collection Manager can be many times greater than the switch, creating an ample archive for each switch. The removable media can be easily replaced and stored for historical records. The X.25-TCP/IP feature of the Access 4000 is available to simultaneously connect to other servers for operations and management using the same or the second X.25 interface. This makes the Access 4000 CDR Collection Manager the most complete, single-box solution for migrating a CO switch to IP networking.

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Operations and Alarms Management of the legacy exchange uses either an X.25 network interface, or a serial port connected locally to a terminal or remotely through an X.28 (PAD) interface. In the legacy configuration, the operation server connected to all the exchanges via an X.25 network, or through multiple leased line or dialup modem connections.

Operations servers often use protocols like FTAM and MTP requiring that any conversion of X.25 that carries the protocol messages across a TCP/IP network MUST preserve the message boundaries of the protocol. Text based command line interfaces do not usually require this, but may have character stream issues that need special handling. There are a number of conversions that can be implemented, assuming the X.25 requirement at the exchange remains.

X.25 Network Replacement When the X.25 network (or network of leased lines or modems) is replaced, each switch and server X.25 interface is connected to an X.25/TCP gateway.

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Conversion of Operations Server to TCP/IP When the server is converted to TCP/IP, and the X.25 network left in place, a centralized conversion of X.25 to TCP is required. The Gateway sits between the X.25 network and the IP network. The server should support any switch-specific protocol using an encapsulation method over TCP.

When the X.25 network is also replaced, a Gateway is required at each switch.

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Example Network Migration The following diagram illustrates that the X.25/TCP Gateway connected to the servers supports multiple simultaneous connections to the exchanges. Each X.25/TCP Gateway at the exchange can have 2 ports connected, either X.25 or serial/X.28. Each X.25 interface to the exchange can support multiple simultaneous connections from both or either the CDR Collection Server or the Operations Server, or each Interface can be dedicated to one server. More than one method of migration is supported in the same network. Features of the example: • • • •

Both CDR collection and operations management included Dedicated or shared X.25 access to the switch for the servers X.25 and serial/X.28 connections to the switch Centralized and distributed CDR collection

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Specifications Software and Protocols X.25 Features • • • • • • • • • •

Selectable DCE or DTE at layer 2 (LAPB) and layer 3 (packet) 1024 logical channels SVC and PVC (any mixture supported simultaneously) Packet sizes: 16-4096 Window sizes: 1-7 (modulo 8), 1-127 (modulo-128/extended) Flow control facilities: packet & window sizes, throughput class Other facilities: reverse charge, etc DTE facilities: called and calling address extension Q-bit and M-bit control X.29 (PAD) support

X.25 / TCP Encapsulation and Conversion methods • • • • • •

X.25 Over TCP (XOT) per RFC 1613 for X.25 transparency RFC1006 for ISO TP0 bridging RAW for byte-streaming MBIT for X.25 More-bit message preservation Q-MBIT for X.25 M-bit and Q-bit preservation LINE mode for legacy command line interfaces over X.25

X.25 to TCP Connection Mapping and Address Translation Incoming X.25 connections are scanned for a match from any or all of: • • • •

X.25 interface port called X.121 address calling X.121 address PID or user data

Matched connections are routed to a TCP outbound connection with: • • • •

destination IP address and TCP port number via specific local IP interface (or VLAN) option via specific local TCP port number option using specified encapsulation or conversion method

TCP to X.25 Connection Mapping and Address Translation Incoming TCP/IP connections are scanned for a match from any or all of: • • • •

TCP port number (mandatory listener) local IP interface (or VLAN) remote IP address remote TCP port number

Matched connections are routed to an X.25 outbound connection with any or all of: • •

X.25 interface port selection destination (called) X.121 address

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• • • •

source (calling) X.121 address PID and userdata X.25 and/or DTE facilities Using specified encapsulation or conversion method

X.28/Serial Features • • • • • •

baud rate (300 – 115200) data bits (5 – 8) parity (odd, even, none) stop bits (1, 1.5, 2) flow control (none, soft-XON/XOFF, modem-RTS/CTS) TCP port connection

System Services The Access 4000 can be managed via a number of system services: • • • • • • • •

Syslog with logging to remote server SNMP SSH and Telnet for system maintenance HTTPS for configuration web interface RADIUS login PAM authentication FTP, SFTP, SCP file transfers for updates and saving configurations NTP client for accurate time synchronization

CDR Collection Option With the CDR collection option, The Access 4000 connects directly to the X.25 interface of the exchange and polls for CDR/AMA record files using the protocols: • • • •

OSI/FTAM client or server AMATPS (BX.25) XFER (Nortel DMS) MTP client or server

Collected files can be transferred to the billing system using: • • •

FTP push or pull SFTP push or pull NFS mounted file server

Transferred files are archived on the local media for long term storage and retrieval with: • •

GZIP Compression Definable archival period

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Hardware Power Requirements The Access 4000 is powered from a 12VDC 1.3A power source. The external AC adapter is rated for: 100-240VAC 50/60Hz input and 12DC, 1.3 Amps output. The maximum power dissipation is as listed below. Voltage

12 VDC*

Current

1300 mA (maximum)

Power

15 Watts

BTU 55 BTU / hour * Unit operates from 100-220 VAC 50/60Hz power adapter

Environmental Specifications Ambient Temperature

5 to 50 degrees C*

Temperature rate of change

3 degrees / hour

Humidity

10% to 95% (non-condensing)

Humidity rate of change

2% / hour

* For short term operation to 55 degrees C

Regulatory Compliances The Access 4000 platform has been tested to comply with the CE requirements for self declaration for EMC and Low Voltage for Information Technology Equipment. The product conforms to the following standards: • CISPR 22:2008-09 / EN 55022:2006 - Class A – Limits and methods of measurement of radio disturbance characteristics of Information Technology Equipment • CISPR 24:1997 + A1:2001 + A2:2002 / EN 55024:1998 + A1:2001 +A2:2003 – Information Technology Equipment – Immunity Characteristics – Limits and Methods of Measurements • IEC 60950 – 1 : 2005 (2nd Edition); EN 60950 – 1 : 2006 (2nd Edition) – Information Technology Equipment - Safety – Part 1: General Requirements • Canadian ICES-003 – Digital Apparatus Issue 4 Feb. 2004 • CSA C22.2 No. 60950-1

Mechanical Dimensions: 6.5” x 7.25” x 1.625” (D x W x H)

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