3Com 3CR17451-91, 3CR17450-91 User Manual

SuperStack® 3 Switch 3870 Family

Getting Started Guide

3CR17450-91 3CR17451-91

http://www.3com.com/

Part No. DUA1745-0AAA02

Published August 2004

3Com Corporation

350 Campus Drive

Marlborough

MA USA 01752-3064

Copyright © 2004, 3Com Corporation. All rights reserved. No part of this documentation may be reproduced in any form or by any means or used to make any derivative work (such as translation, transformation, or adaptation) without written permission from 3Com Corporation.

3Com Corporation reserves the right to revise this documentation and to make changes in content from time to time without obligation on the part of 3Com Corporation to provide notification of such revision or change.

3Com Corporation provides this documentation without warranty, term, or condition of any kind, either implied or expressed, including, but not limited to, the implied warranties, terms or conditions of merchantability, satisfactory quality, and fitness for a particular purpose. 3Com may make improvements or changes in the product(s) and/or the program(s) described in this documentation at any time.

If there is any software on removable media described in this documentation, it is furnished under a license agreement included with the product as a separate document, in the hard copy documentation, or on the removable media in a directory file named LICENSE.TXT or !LICENSE.TXT. If you are unable to locate a copy, please contact 3Com and a copy will be provided to you.

UNITED STATES GOVERNMENT LEGEND

If you are a United States government agency, then this documentation and the software described herein are provided to you subject to the following:

All technical data and computer software are commercial in nature and developed solely at private expense. Software is delivered as “Commercial Computer Software” as defined in DFARS 252.227-7014 (June 1995) or as a “commercial item” as defined in FAR 2.101(a) and as such is provided with only such rights as are provided in 3Com’s standard commercial license for the Software. Technical data is provided with limited rights only as provided in DFAR 252.227-7015 (Nov 1995) or FAR 52.227-14 (June 1987), whichever is applicable. You agree not to remove or deface any portion of any legend provided on any licensed program or documentation contained in, or delivered to you in conjunction with, this User Guide.

Unless otherwise indicated, 3Com registered trademarks are registered in the United States and may or may not be registered in other countries.

3Com, the 3Com logo and SuperStack are registered trademarks of 3Com Corporation.

Intel and Pentium are registered trademarks of Intel Corporation. Microsoft, MS-DOS, Windows, and Windows NT are registered trademarks of Microsoft Corporation. Novell and NetWare are registered trademarks of Novell, Inc. UNIX is a registered trademark in the United States and other countries, licensed exclusively through X/Open Company, Ltd.

IEEE and 802 are registered trademarks of the Institute of Electrical and Electronics Engineers, Inc.

IAll other company and product names may be trademarks of the respective companies with which they are associated.

ENVIRONMENTAL STATEMENT

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Establishing environmental performance standards that comply with national legislation and regulations.

Conserving energy, materials and natural resources in all operations.

Reducing the waste generated by all operations. Ensuring that all waste conforms to recognized environmental standards. Maximizing the recyclable and reusable content of all products.

Ensuring that all products can be recycled, reused and disposed of safely.

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End of Life Statement

3Com processes allow for the recovery, reclamation and safe disposal of all end-of-life electronic components.

Regulated Materials Statement

3Com products do not contain any hazardous or ozone-depleting material.

Environmental Statement about the Documentation

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CONTENTS

ABOUT THIS GUIDE

Conventions 8

Related Documentation 9

Accessing Online Documentation 9

Documentation Comments 10

1 INTRODUCING THE SUPERSTACK 3 SWITCH 3870

About the Switch 3870		12
Summary of Hardware Features				12
Switch 3870 — Front View Detail				13
10BASE-T/
100BASE-TX/
1000BASE-T Ports		14
Dual Personality SFP Ports			14
Console Port	14
LEDs 15
Switch 3870 — Rear View Detail				17
Expansion Module Slot			17
Power Socket	17
Redundant Power System Socket 17
Stacking Cable Ports		17
Default Settings	18

2 INSTALLING THE SWITCH

Package Contents	22
Choosing a Suitable Site		22
Rack-mounting	23
Placing Units On Top of Each Other			24
The Power-up Sequence		25
Powering-up the Switch 3870			25

	Checking for Correct Operation of LEDs							25
	Connecting a Redundant Power Supply							25
	Choosing the Correct Cables				26
	SFP Operation	27
	Approved SFP Transceivers			27
	Inserting an SFP Transceiver				27
	Removing an SFP Transceiver				29
3 SETTING UP FOR MANAGEMENT
	Setting Up Overview		32
	IP Configuration 33
	Preparing for Management				34
	Manually Configuring IP Information					35
	Connecting to the Console Port					35
	Viewing Automatically Configured IP Information								38
	Using 3Com Network Supervisor					38
	Connecting to the Console Port					38
	Methods of Managing a Switch				41
	Command Line Interface Management							41
	Web Interface Management				42
	SNMP Management		42
	Setting Up Command Line Interface Management								42
	CLI Management via the Console Port							43
	CLI Management over the Network						43
	Setting Up Web Interface Management						44
	Pre-requisites	44
	Web Management Over the Network							45
	Setting Up SNMP Management				45
	Pre-requisites	45
	Default Users and Passwords			46
	Changing Default Passwords				46
4 PROBLEM SOLVING
	Solving Problems Indicated by LEDs					48
	Solving Hardware Problems			49
	Solving Communication Problems				51
	Solving Software Upgrade Problems					53

A	SAFETY INFORMATION
	Power Cord Set — Japan			55
	Important Safety Information				56
	L’information de Sécurité Importante					58
	Wichtige Sicherheitsinformationen					61
B
	PIN-OUTS
	Null Modem Cable		63
	PC-AT Serial Cable		63
	Modem Cable	64
	RJ-45 Pin Assignments			64
C
	TECHNICAL SPECIFICATIONS
	Switch 3870	67
D
	OBTAINING SUPPORT FOR YOUR PRODUCT
	Register Your Product to Gain Service Benefits 69
	Purchase Value-Added Services				69
	Troubleshoot Online		69
	Access Software Downloads				70
	Contact Us	70
	Telephone Technical Support and Repair 70

INDEX

REGULATORY NOTICES

ABOUT THIS GUIDE

This guide provides all the information you need to install and use 3Com® SuperStack® 3 Switch 3870 (24 and 48 port) in its default state.

The guide is intended for use by network administrators who are responsible for installing and setting up network equipment; consequently, it assumes a basic working knowledge of LANs (Local Area Networks).

Please refer to the CD-ROM that accompanies your Switch for the following:

■Management Interface Reference Guide — an online guide which gives you detailed information on how to use the web interface and command line interface to manage the Switch.

■Other documentation relating to the 3Com SuperStack 3 Switch 3870.

■3Com Network Supervisor — a powerful network management tool for small to medium enterprise networks.

■A number of other useful applications.

If the information in the release notes that are shipped with your product differ from the information in this guide, follow the instructions in the release notes.

Most user guides and release notes are available in Adobe Acrobat Reader Portable Document Format (PDF) or HTML on the 3Com World Wide Web site:

http://www.3com.com/

8 ABOUT THIS GUIDE

Conventions	Table 1 and Table 2 list conventions that are used throughout this guide.
	Table 1	Notice Icons
	Icon	Notice Type	Description
		Information note	Information that describes important features or
			instructions.
		Caution	Information that alerts you to potential loss of data or
			potential damage to an application, system, or device.
		Warning	Information that alerts you to potential personal
			injury.

Table 2 Text Conventions

Convention	Description
Screen displays	This typeface represents information as it appears on the
	screen.
Syntax	The word “syntax” means that you must evaluate the syntax
	provided and then supply the appropriate values for the
	placeholders that appear in angle brackets. Example:
	To change your password, use the following syntax:
	system password <password>
	In this example, you must supply a password for <password>.
Commands	The word “command” means that you must enter the
	command exactly as shown and then press Return or Enter.
	Commands appear in bold. Example:
	To display port information, enter the following command:
	bridge port detail
The words “enter”	When you see the word “enter” in this guide, you must type
and “type”	something, and then press Return or Enter. Do not press
	Return or Enter when an instruction simply says “type.”
Keyboard key names	If you must press two or more keys simultaneously, the key
	names are linked with a plus sign (+). Example:
	Press Ctrl+Alt+Del
Words in italics	Italics are used to:
	■ Emphasize a point.
	■ Denote a new term at the place where it is defined in the
	text.
	■ Identify menu names, menu commands, and software
	button names. Examples:
	From the Help menu, select Contents.
	Click OK.

Related Documentation

9

Related	In addition to this guide, each Switch documentation set includes the
Documentation	following:
	■ Management Quick Reference Guide
		This guide contains:
		■ a list of software features supported by each Switch.
		■ a summary of the web interface and command line interface
		commands for the Switch.
	■	Release Notes
		These notes provide information about the current software release,
		including new features, modifications, and known problems.
	■	Switch Implementation Guide
		This guide contains information on the features supported by your

Switch and how they can be used to optimize your network. It is supplied in PDF format on the CD-ROM that accompanies the Switch.

■ Management Interface Reference Guide

This guide provides detailed information about the web interface and command line interface that enable you to manage the Switch. It is supplied in HTML format on the CD-ROM that accompanies the Switch.

There are other publications you may find useful:

■ Documentation accompanying the Expansion Module.

■ Documentation accompanying the SFP Transceivers.

■ Documentation accompanying 3Com Network Supervisor. This is supplied on the CD-ROM that accompanies the Switch.

Accessing Online The CD-ROM supplied with your Switch contains the following online Documentation documentation:

■Switch Implementation Guide (PDF format).

■Switch Management Interface Reference Guide (HTML format).

■Other documentation relating to the Switch 3870 (PDF format).

10 ABOUT THIS GUIDE

To access the online documentation from the CD-ROM:

1Insert the CD-ROM into the relevant CD-ROM drive. If your PC has auto-run enabled, a splash screen will be displayed automatically.

2Select the Documentation section from the contents page.

If the online documentation is to be accessed from a local drive or server, you will need to access the CD-ROM contents via the root directory and copy the files from the CD-ROM to a suitable directory.

■The HTML Reference Guide is stored in the Docs/referenceguide on the CD-ROM. The documentation is accessed using the index.htm file.

■The PDF Implementation Guide is stored in the Docs/implementation directory of the CD-ROM.

	3Com recommends that you copy the Docs/referenceguide
	directory as a whole to maintain the structure of the files.
Documentation	Your suggestions are very important to us. They will help make our
Comments	documentation more useful to you. Please e-mail comments about this
	document to 3Com at:
	[e-mail]
	Please include the following information when commenting: Document
	title, Document part number (on the title page) and Page number (if
	appropriate).
	Example:
	Part Number DUA1745-0AAA01
	3Com SuperStack 3 Switch 3870 Getting Started Guide
	Page 21

1	INTRODUCING THE SUPERSTACK 3
	SWITCH 3870

This chapter contains introductory information about the Switch 3870 and how it can be used in your network. It covers summary information about the hardware and the following topics:

■About the Switch 3870

■Switch 3870 — Front View Detail

■Switch 3870 — Rear View Detail

■Default Settings

12 CHAPTER 1: INTRODUCING THE SUPERSTACK 3 SWITCH 3870

About the Switch The Switch 3870 24 port unit is a mixed media device which consists of:

3870

■24 10BASE-T/100BASE-TX/1000BASE-T RJ-45 ports, of which 4 are Dual Personality 10/100/1000BASE-T/1000BASE-X SFP ports

■4 Dual Personality 10/100/1000BASE-T/1000BASE-X SFP ports

The Switch 3870 48 port unit is a mixed media device which consists of:

■48 10BASE-T/100BASE-TX/1000BASE-T RJ-45 ports, of which 4 are Dual Personality 10/100/1000BASE-T/1000BASE-X SFP ports

■4 Dual Personality 10/100/1000BASE-T/1000BASE-X SFP ports

For information about using the software features of the Switch, refer to the “Switch Management Interface Reference Guide” on the CD-ROM that accompanies the Switch.

Summary of Table 3 summarizes the hardware features that are supported by the

Hardware Features Switch 3870.

Table 3 Hardware features

Feature	Switch 3870
MAC Addresses	Up to 16,000 supported
Forwarding Modes	Store and Forward
Auto-negotiation	Supported on all ports
Auto MDI/MDIX	Supported on all ports
Duplex Modes	Half and full duplex on all ports
SFP Gigabit Ethernet	Supports fiber Gigabit Ethernet short-wave (SX),
Ports	long-wave (LX) and long-haul (LH70) transceivers in any
	combination
Flow Control	Supported on all ports
Traffic Prioritization	Supported (IEEE Std 802.1D, 1998 Edition)
	Eight traffic queues per port
Fast Ethernet and	Auto-negotiating 10BASE-T/100BASE-TX/1000BASE-T
Gigabit Ethernet Ports	and SFP ports
RPS Support	Connects to SuperStack 3 Advanced Redundant Power
	System (ARPS).
Mounting	19-inch rack or stand-alone mounting

Switch 3870 — Front View Detail 13

Switch 3870 —	Figure 1			Switch 3870 (24 ports) — front view
Front View Detail
																								Stack Status/
																								Stack Master LEDs
													Port Status LEDs											Fault LED		Power/Self Test LED
																				Module Activity LED						Module Status LED
																											Console Port
	1	13	2	14	3	15	4	16	5	17	6	18	7	19	8	20	9	21	10	22	11	23	12	24
																								Fault Power
																								Stack	S
																								Master
																								Module	P S			Unit LED
																								Activity		SuperStack 3 Switch 3870 24-port
																								21	22	23	24

		Dual Personality
	10/100/1000BASE-T Ports	10/100/1000BASE-T/
		1000BASE-X SFP Ports

Figure 2 Switch 3870 (48 ports) — front view

																																																Stack Status/
																																																Stack Master LEDs
																					Port Status LEDs																										Fault LED		Power/Self Test LED
																																										Module Activity LED							Module Status LED
																																																	Console Port
1	13	2	14	3	15	4	16	5	17	6	18	7	19	8	20	9	21	10	22	11	23	12	24	25	37	26	38	27	39	28	40	29	41	30	42	31	43	32	44	33	45	34	46	35	47	36	48	Fault Power
																																																Stack	S
																																																Master
																																																Module P	S
																																																Activity	SuperStack 3 Switch 3870 48-port	Unit LED

45

46

47

48

10/100/1000BASE-T Ports

Dual Personality

10/100/1000BASE-T/ 1000BASE-X SFP Ports

WARNING: RJ-45 Ports. These are shielded RJ-45 data sockets. They cannot be used as standard traditional telephone sockets, or to connect the unit to a traditional PBX or public telephone network. Only connect RJ-45 data connectors, network telephony systems, or network telephones to these sockets.

Either shielded or unshielded data cables with shielded or unshielded jacks can be connected to these data sockets.

14 CHAPTER 1: INTRODUCING THE SUPERSTACK 3 SWITCH 3870

10BASE-T/ The 10BASE-T/100BASE-TX/1000BASE-T ports have RJ-45 connectors and 100BASE-TX/ are configured as Auto MDIX (cross-over).

1000BASE-T Ports

The default state for these ports is auto-negotiation enabled, where the speed, duplex and flow control modes of a link are automatically detected to provide the highest available bandwidth with the link partner.

Alternatively, auto-negotiation can be disabled. These ports can be manually configured to 10 Mbps half duplex, 100 Mbps half duplex, 10 Mbps full duplex or 100 Mbps full duplex. It is not possible to

manually configure a 1000 Mbps link as auto-negotiation is mandatory in the 1000 Mbps standard. If auto-negotiation is disabled, Auto MDIX cannot function and the ports are fixed as MDIX (cross-over) mode.

If auto-negotiation is disabled on a 1000 Mbps port, the speed will drop to the highest available speed. By default this is 100 Mbps.

Dual Personality SFP The 4 Dual Personality SFP (Small Form Factor Pluggable) ports support Ports fiber Gigabit Ethernet short-wave (SX), long-wave (LX) and long-haul

(LH70) transceivers in any combination. This offers you the flexibility of using SFP transceivers to provide connectivity between the Switch and remote 1000 Mbps workgroups or to create a high capacity aggregated link backbone connection.

The SFP ports are capable of auto-negotiating flow control. As the speed and duplex modes are fixed by the media type, only the flow control is negotiated with the link partner. Alternatively, auto-negotiation can be disabled and the flow control setting can be manually configured.

Console Port The console port allows you to connect a terminal and perform remote or local out-of-band management. As the console port on the Switch is an RJ-45 port, you will need to connect an RJ-45 to DB9 converter cable to a standard null modem cable in order to connect a terminal.

The standard null modem cable is set to autobaud (up to a maximum of 19,200 baud), 8 data bits, no parity and 1 stop bit.

Switch 3870 — Front View Detail 15

LEDs Table 4 lists LEDs visible on the front of the Switch, and how to read their status according to color. For information on using the LEDs for problem solving, see “Checking for Correct Operation of LEDs” on page 25.

Table 4	LED behavior
LED	Color	Indicates
Port Status/Packet LEDs
	Green	A high speed (1000 Mbps) link is present, and the port
		is enabled.
	Green flashing	A high speed (1000 Mbps) link is present and active.
	Yellow	A low speed (10/100 Mbps) link is present, and the
		port is enabled.
	Yellow flashing	A low speed (10/100 Mbps) link is present and active.
	Green for one	POST in operation, all LEDs perform a one second lamp
	second, Amber	test.
	for one second,
	then OFF until
	operational.
	Alternate yellow	A port has failed a loop back test during POST.
	then green
	flashing (fast)
	Alternate yellow	A link is present but the port has been disabled.
	then green
	flashing
	Off	No link is present.
Stacking Status LED
	Green	The uplink/downlink is operating normally.
	Yellow	One-sided connection (one side of the cable is
		connected but the other side is not).
	Off	No stacking link is present.
Stack Master LED
	Green	Master unit - normal stack operation status.
	Yellow	Slave unit - normal stack operation status.
	Yellow flashing	The system is in arbitration/election status.
	Off	The system is not stacked.

16 CHAPTER 1: INTRODUCING THE SUPERSTACK 3 SWITCH 3870

LED	Color	Indicates
Module LEDs
Packet	Yellow	Packets are being transmitted/received on the port.
	Off	No packets are being transmitted/received on the port.
Status	Green	The Module is installed and supported and the Link
		Status has been determined.
	Yellow	The Module is installed and supported but there is no
		link or an indeterminate link status.
	Yellow flashing	The Module is installed but not supported or has failed
		POST.
	Off	The Module is not installed.
Unit LED
	Green	The Switch is stacked and the position within the stack
		is displayed.
	Off	The Switch is not stacked.
Power/Self Test LED
	Green	The Switch is powered-up and operating normally.
	Green flashing	The Switch is either downloading software or is
		initializing (which includes running a Power On Self
		Test).
	Yellow	The Switch is faulty.
	Off	The Switch is not receiving power or there is a fault
		with the Power Supply unit.
Fault LED
	Red	The Switch and/or the PSU and/or the Module are
		above critical temperature but below critical shut down
		temperature. Fans are operating normally.
	Off	The Switch, PSU and the Module are below critical
		temperature. One or more fans have failed.

Switch 3870 — Rear View Detail 17

Switch 3870 — Rear Figure 3	Switch 3870 — rear view
View Detail
Power Socket	Expansion Module Slot
		Stacking Cable Port (Up)
	D
	O	U
	W	P
	N
Redundant Power System Socket	Stacking Cable Port (Down)

Expansion Module You can use this slot to install an Expansion Module. Contact your Slot supplier for further information.

WARNING: When an Expansion Module is not installed, ensure the blanking plate is fitted by tightening all screws with a suitable tool.

Power Socket Each Power Supply automatically adjusts its power setting to any power voltage in the range 100-240 VAC.

Redundant Power To protect against internal power supply failure, you can use this socket System Socket to connect the Switch to a SuperStack 3 Advanced Redundant Power

System. See “Connecting a Redundant Power Supply” on page 25.

Stacking Cable Ports You can use these ports to connect the following cables:

■Stacking Cable (3C17462) — which enables you to stack together two switches up to three rack units apart.

■Resilient Stacking Cable (3C17463) — which enables you to stack together two switches up to sixteen rack units apart.

You can stack together any combination of 3870 24 port and 48 port units, up to a maximum of eight units.

For more information on how to connect a stacking cable to your switch units, please refer to the Installation Guide that accompanies your cable.

18 CHAPTER 1: INTRODUCING THE SUPERSTACK 3 SWITCH 3870

Some combinations of stacked 24 and 48 port units restrict the number of modules supported by the stack. Table 5 shows which stack configurations restrict the number of supported modules:

Table 5 Maximum Stack Configurations

Type of Unit		Total Units in the Stack	Maximum Modules
48 Port	24 Port
0	8	8	8
8	0	8	0
7	1	8	2
7	0	7	4
6	2	8	4
6	1	7	6
6	0	6	6

Default Settings Table 6 shows the default settings for the Switch 3870. If you initialize one of the Switch units, it is returned to these defaults.

Table 6 Default Settings

Feature	Switch 3870
Port Status	Enabled
Port Speed	Auto-negotiated
Duplex Mode	Auto-negotiated
Flow Control	Auto-negotiated
Broadcast Storm Control	Enabled
	High threshold: 3000 broadcast frames per
	second — Notify and filter
	Low threshold: 1500 broadcast frames per
	second — Notify and unfilter
Virtual LANs (VLANs)	All ports belong to the untagged Default VLAN
	(VLAN 1)
Multicast Filtering	IGMP filtering enabled
Rapid Spanning Tree Protocol	Enabled

Default Settings 19

Feature	Switch 3870
Link Aggregation Control	Disabled per port
Protocol (LACP)
Spanning Tree Protocol	Enabled
Smart Auto-sensing	Enabled

If you initialize a Switch unit by selecting System > Control > Initialize in the Web interface or by entering system control initialize in the Command Line Interface, the following settings are retained to allow you to connect to and manage the Switch:

■IP Address

■Subnet Mask

■Default Gateway

20 CHAPTER 1: INTRODUCING THE SUPERSTACK 3 SWITCH 3870

2	INSTALLING THE SWITCH

This chapter contains the information you need to install and set up the Switch 3870. It covers the following topics:

■Package Contents

■Choosing a Suitable Site

■Rack-mounting

■Placing Units On Top of Each Other

■The Power-up Sequence

■SFP Operation

WARNING: Safety Information. Before installing or removing any components from the Switch 3870 or carrying out any maintenance procedures, you must read the safety information provided in Appendix A of this guide.

AVERTISSEMENT: Consignes de sécurité. Avant d'installer ou d'enlever tout composant de Switch 3870 ou d'entamer une procédure de maintenance, lisez les informations relatives à la sécurité qui se trouvent dans l'Appendice A de ce guide.

VORSICHT: Sicherheitsinformationen. Bevor Sie Komponenten aus dem Switch 3870 entfernen oder den Switch 3870 hinzufügen oder Instandhaltungsarbeiten verrichten, lesen Sie die Sicherheitsanweisungen, die in Anhang A in diesem Handbuch aufgeführt sind.

22 CHAPTER 2: INSTALLING THE SWITCH

Package Contents	■	Switch unit
	■	CD-ROM
	■	This Guide
	■ Management Quick Reference Guide
	■	Release Notes
	■	Warranty Flyer
	■	Power Cord
	■ 2 x securing brackets
	■	8 x screws
	■ 4 x rubber feet
	■ RJ45 to DB9 converter cable
Choosing a Suitable	The Switch 3870 is suited for use in an internal wiring closet, a network
Site	room, or telecommunications room, where it can be mounted in a
	standard 19-inch equipment rack, or free-standing.

CAUTION: Ensure that the ventilation holes are not obstructed.

To ensure this product provides optimum performance, high speed fans are used to provide ventilation. These fans have a high audible output while running at full speed. The Switch 3870 is designed to reduce the fan speed shortly after power on (if thermal conditions allow) which will also reduce the fan noise generated.

When deciding where to position the Switch, ensure that: ■ Cabling is located away from:

■ sources of electrical noise such as radios, transmitters and broadband amplifiers.

■ power lines and fluorescent lighting fixtures.

■ The Switch is accessible and cables can be connected easily.

■ Water or moisture cannot enter the case of the Switch.

■ Air flow is not restricted around the Switch or through the vents in the side of the Switch. 3Com recommends that you provide a minimum of 25 mm (1 in.) clearance.

■ Air temperature around the Switch does not exceed 40 °C (104 °F).

Rack-mounting 23

If the Switch is installed in a 19-inch rack or closed assembly its local air temperature may be greater than room ambient temperature.

■ The air is as free from dust as possible.

■ The Switch is situated away from sources of conductive (electrical) dust, for example laser printers.

	■ The unit is installed in a clean, air conditioned environment.
	■ The AC supply used by the Switch is separate to that used by units
	that generate high levels of AC noise, for example air conditioning
	units.
	■ No more than four Switch units are placed on top of one another, if
	the units are free-standing.
Rack-mounting	The Switch 3870 is 1U high and will fit in most standard 19-inch racks.
	CAUTION: Disconnect all cables from the Switch before continuing.
	Remove all self adhesive pads from the underside of the Switch if they
	have been fitted.
	CAUTION: If you use a shelf or support ensure that it will not obstruct
	the air flow through the side panels of the Switch.
	To rack-mount your Switch:
	1 Place the Switch the right way up on a hard flat surface, with the front
	facing towards you.
	2 Locate a securing bracket over the mounting holes on one side of the
	Switch, as shown in Figure 4.
	3 Insert the four screws and tighten with a suitable screwdriver.