Instruction/ maintenance manual of the product Switch 4500 26-Port 3Com
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3Com ® Switch 4500 Family Getting Started Guide Switch 4500 26-Port Switch 4500 50-Port Switch 4500 PWR 26-Port Switch 4500 PWR 50-Port www.3Com.com Part No.
3Com Corporation 350 Campus Drive Marlbor ough, MA USA 01752-3064 Copyright © 2006-2007, 3Com Corporation . All rights reserved . No part of this doc umentati on may be reprod uced in any form or by .
C ONTENTS A BOUT T HIS G UIDE Before Y ou Start 7 Conventions 8 Related Documentat ion 8 Documentation Comments 8 1 I NTRODUCING THE S WITCH 4500 F AMILY About the Switch 45 00 12 Summary of Har dware.
Using Power over Ethernet 30 The Power -up Seque nce 32 Powering-up th e Switch 4500 32 Checking for Correct Operation of LEDs 32 Choosing the Correct Cables for the 1000BASE-X SFP Ports 33 SFP Operat.
4 C REA T I N G A S TACK How T o Inter connect Units 59 Guidelines For Inte rco nnecting Units 60 Unit Numbering within the Stack 61 5 P ROB L E M S OLVING Solving Problems Indicated by LEDs 64 Solvin.
Ethernet Port RJ-45 Pin Assignments 88 B T ECHNICAL S PECIFICATIONS Switch 4500 (26 Port) 91 Switch 4500 (50 Port) 92 Switch 4500 PWR (26 Port ) 93 Switch 4500 PWR (50 Port ) 94 RPS 95 Earthing Lead 9.
A BOUT T HIS G UIDE This guide provides all the information you need to install and use the following switches in their default state: ■ Switch 4500 26 -Port (3CR175 61-91) ■ Switch 4500 50 -Port .
8 A BOUT T HIS G UIDE Conventions Ta b l e 1 lists con ventions that are used throughout this guide. Related Documentation In addition to this guide, each Switch documentat ion set includes the follow.
Documentation Comments 9 Please include the following information when commenting: ■ Document title ■ Document part number (on the title page) ■ Page number (if appropriate) Example: Part Number 10015034 Rev .
10 A BOUT T HIS G UIDE.
1 I NTR ODUCING THE S WITCH 4500 F AMILY This chapter contain s introductory information about the Switch 4 500 and how it can be used in your network.
12 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY About the Switch 4500 The Switch 4500 Family are mixed media devices. T able 2 summarizes what each Switch consists of: Ta b l e 2 Switch 4500 Fami.
Switch 4500 — Front View Detail 13 Summary of Ha rdw a re F e a tu res Ta b l e 3 summarizes the hardware features that ar e supported by the Switch 4500.
14 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY Figure 2 Switch 4500 50-Port — fr ont view Figure 3 Switch 4500 26-Port PWR - fr ont view Figure 4 Switch 4500 50-Port PWR - fr ont view WAR N I NG : RJ-45 Ports. These are shielded RJ-45 data sockets.
Switch 4500 — Front View Detail 15 10BASE-T/ 100BASE-TX Ports The Switch 4500 has 24 or 48 au to-neg otiating 10BASE-T/100BASE-TX ports configured as Auto MDIX (cro ss-over).
16 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY T wo 1000Base-T SFP tran sceivers are included with these units. Thes e SFP transceivers can be inserted in any of th e four SFP slots to provide copper Gigabit connectivity .
Switch 4500 — Front View Detail 17 Unit LED The Unit LED is a seven segment display visible on the front of the Switch. The Unit LE D can be used to indica te the un it number in a fabric, POST test ID and softw are upgrade information. In the unlikely event of a hardwar e fault occurr ing, the Unit LED may be used to help diagnose the problem.
18 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY RPS LED (3CR17571-91 and 3CR17572-9 1 only) Green AC and RPS supply connected. Yellow AC failed or not connected.
Switch 4500 — Rear View Detail 19 Switch 4500 — Rea r View Detail Figure 5 Switch 4500 — r ear view Figure 6 Switch 4500 PWR - r ear view Power Socket Th e Switch automatically adjusts its power setting to any supply voltage in the range 100-240 V AC.
20 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY A VVERTENZA: Prima di installare o rimu overe qualsiasi componente dello Switch 4500 Family o di eseguire qualsiasi procedura di manutenzione, leggere le inform azioni di sicurezza riportate nell'Appendice A di questa guida.
Default Settings 21 T raffic Prioritization All ports prioritize NBX VoIP traffic (LAN and IP). All ports set to “best effort” for all other traffic.
22 C HAPTER 1: I NTRODUCING THE S WITCH 4500 F AMILY.
2 I NSTALLING THE S WITCH This chapter contains supplemental info rmation on setting up y our Switch 4500. These details are intended to be read together with the printed documents that accompany y our switch.
24 C HAPTER 2: I NSTALLING THE S WITCH Important Steps Before Pr oceeding Before pr oceeding, make sure to access the Switch 4500 information on 3Com’ s W eb site at www .
Connecting a Redundant Power Supply to your Switch 450 0 PWR 25 with the 3Com Power -over -Ethernet (P oE) network switches. In order to meet the IEEE 802.3af (PoE) specification, the -48V output mu st be isolated from earth (ground) and meet the isolation requirements in that specification.
26 C HAPTER 2: I NSTALLING THE S WITCH WAR NI N G : Any RPS must be approved as a SEL V output in accord ance with IEC 6 0 9 50-1/UL 6 0 9 50-1/EN 6 0 9 50-1. WAR NI N G : The characteri stics of the Switch 4500 DC supply input are given in Appendix B on page 91 .
Connecting a Redundant Power Supply to your Switch 450 0 PWR 27 Ta b l e 6 Switch Power Inputs Specifying the Redundant Power System 3Com’ s r edundant power so lution allows the use of any off-the-shelf -48V DC RPS that meets the requir ements defined in Appendix B on page 91 .
28 C HAPTER 2: I NSTALLING THE S WITCH Ta b l e 7 Power Availability The -48V DC power distribution provides the mechanism to connect to the Switch 4500 PWR. The distribution consis ts of a number of circuit breakers and connection terminals for the positive (common) and negative -48V outputs.
Connecting a Redundant Power Supply to your Switch 450 0 PWR 29 WAR NI N G : Ensure that the circuit breaker in the RPS is in the open (off) position when connecting the ca ble to the RPS and the cable and connector to the Switch .
30 C HAPTER 2: I NSTALLING THE S WITCH The -48V DC power will take priority over the AC mains and will power the Switch if it is connected. Connecting the Earthing Cable Use the earthing cable that accompan ies your Switch if the le ngth is suitable. Alter natively use the earthin g cable specification as defined in Appendix B on page 91 .
Connecting a Redundant Power Supply to your Switch 450 0 PWR 31 network cable is requir ed to provide both power and network connectivity . ■ Incr eased Reliability — a device power ed by a PoE Switch will be able to take advantage of the facilities available to the Switch.
32 C HAPTER 2: I NSTALLING THE S WITCH The Power -up Sequence The following sections describe how to get your Switch 4500 powered-up and ready for operation. Powering-up the Switch 4500 Use the following sequence of steps to power -up the Switch. 1 Plug the power cor d into the power socket at the rear of the Switch.
The Power-up Sequence 33 Choosing the Corr ect Cables for the 1000BASE-X SFP Ports The 1000BASE-SX SFP transceiver supports a direct connection to a multi-mode fiber -optic cable. The 1 000BASE-LX SFP tran sceiver supports a dir ect connecti on to single-mod e and multi-mode fiber -optic cables.
34 C HAPTER 2: I NSTALLING THE S WITCH SFP Operation The following sections describes how to select and use an SFP transcei ver in an SFP port. Approved SFP T ransceivers The following list of approved Gigabit Ether net SFP transceivers is corr ect at the time of publication.
SFP Operation 35 Inserting an SFP T ranscei ver Use the following sequence of steps to activate the SFP ports: SFP transceivers are hot-insertabl e and hot-swappab le. Y ou can remove them from and insert them into an appropriate SFP port without having to power down the Switch.
36 C HAPTER 2: I NSTALLING THE S WITCH Packing and Shipping the Switch 4500 This section describes how to correctly package your Switch 4500 should you need to return the Switch to 3Com. WAR NI N G : The unit should be packaged sa fely to ensure that you do not invalidate the repair .
3 S ETTING U P FOR M ANAGEMENT T o make full use of the featur es offer ed by your Switch, and to change and monitor the way it works, y ou have to access the management software that r esides on the Switch.
38 C HAPTER 3: S ETTING U P FOR M ANAGEMENT Methods of Managing a Switch T o manage your Switch you can use one of the following methods: ■ Command line interface management ■ Command line interfa.
Methods of Managing a Switch 39 Command Line Interface Management using SSH The Switch 4500 sup ports Secure Shell version 2.0 (SSHv2.0), allowing secure access to the Command Li ne Interface of the Switch.
40 C HAPTER 3: S ETTING U P FOR M ANAGEMENT Setting Up Overview This section gives an overview of what you need to do to get your Switch set up and rea dy for manage ment when it is in its default state. The whole setup process is summarized in Figur e 14 .
Setting Up Overview 41 CAUTION: T o protect yo ur Switch from unauthorized access, yo u must change all three default passwords as soon as possible, even if you do not intend to actively manage your Swit ch. For more inform ation on defau lt users and changing default passwords, see “Default Users and Passwords” on page 56 .
42 C HAPTER 3: S ETTING U P FOR M ANAGEMENT For a detailed description of how au tomatic IP configu ration operat es, refer to the Configuration G uide available on 3Com’ s Web Site at www .3com.com. Y ou should use the automatic IP configu ration method if: ■ your network uses DHCP to a llocate IP information, or ■ flexibility is needed.
Manually Configuring IP Informatio n 43 Manually Configuring IP Information Y ou can manually configure the Switch IP information in the following ways: ■ Connecting to the console port — connect a workstation using a console cable to the console port of the Switch .
44 C HAPTER 3: S ETTING U P FOR M ANAGEMENT Connecting the W orkstat ion to the Switch 1 Connect the workstation to the console port using the console cable as shown in Figure 15 .
Manually Configuring IP Informatio n 45 2 At the login and password prompts, enter admin as your user name and press Return and at the password prompt press Return again. If you have logged on correctly , <4500> should be displayed as shown in Figure 16 .
46 C HAPTER 3: S ETTING U P FOR M ANAGEMENT If you do not intend to use the command line interface via the conso le port to ma nage the Switc h, you can disc onnect the ser ial cable and cl ose the terminal emulator softwar e .
Manually Configuring IP Informatio n 47 Connecting the Workstation to the Switch 1 Connect the workstation to a front panel port using an Ethernet cable as shown in Figure 17 .
48 C HAPTER 3: S ETTING U P FOR M ANAGEMENT 4 T o enter basic setup information for the Switch, select Administration > IP Setup and then follow the wizard through various system screens to enter the IP address and subnet mask that you want the Switch to use when it is connected to the network.
Viewing Automaticall y Configured IP Informatio n 49 Figure 18 User View Login via T elnet 4 Enter th e system-view command and Enter . 5 Enter interface vlan 1 and Enter . 6 Enter the IP address and subnet mask for the Sw itch as follows: ip address xxx.
50 C HAPTER 3: S ETTING U P FOR M ANAGEMENT ■ Connecting to the Console Port — connect a workstation using a console cable to the co nsole port of the Sw itch. Y ou can t hen view the IP information automatically a ssigned to the Switch using the command line interface (CLI).
Viewing Automaticall y Configured IP Informatio n 51 If the login prompt does not begin im mediately , press Re turn a few times until it starts. 3 At the login and password prompts, enter admin as your user name and press Return at the password prompt.
52 C HAPTER 3: S ETTING U P FOR M ANAGEMENT Setting Up Command Line Interface Management This section describes how you can set up command line interface management using a local console po rt connection or over the network. User Interface Overview User interface configuration is provided by the Switch to configure and manage the port data.
Setting Up Command Line Interface Management using SSH 53 (where xxx. xxx.xxx.xxx is the IP addr ess of the Switch) If opening a T elnet session via third party software you w ill need to enter the IP address in the format suitable for that software.
54 C HAPTER 3: S ETTING U P FOR M ANAGEMENT 5 Open an SSH session and acce ss the Switch using the Switch’ s IP address and port number . The first time you connect to the switch the client will ask you to confirm that the host key is correct for the device.
Setting Up S NMP Managemen t V1 or V2 55 For the browser to operate the web in terface corr ectly , JavaScript™ and Cascading Style Sheets must be enabled on your browser . These features are enabled on a browser by default. Y ou will only need to enable them if you have changed y our browser settings.
56 C HAPTER 3: S ETTING U P FOR M ANAGEMENT Pre-r equisites ■ Documentation supplied with the SNMP netwo rk management application software. The default read community string is public . T o change this setting in System View , enter display snmp community.
Default Users and Passwords 57 Use the admin default user name (no password) to login and carr y out initial Switch setup. T o set a passwor d for the admin user in the CLI, enter the following from system view: [4500] local-user admin <cr> [4500-luser-admin] password simple xxxxxxxx (where xxxxxxxx is your chosen password ).
58 C HAPTER 3: S ETTING U P FOR M ANAGEMENT.
4 C RE A T I N G A S TACK This chapt er contains the inf ormation you nee d to create a stack. It covers the following topics: ■ How T o I nterconnect Units ■ Guidelines For Interconnecting Units .
60 C HAPTER 4: C REATING A S TACK As with all Switch 4500 CLI commands, the format for entering a port- specific command is x/y/z, where x = unit number , y = module number (in the case of the Switch 4500 this will always be 0), z = port number .
Unit Numbering within the Stack 61 ■ When a port is operating in st ack mode it will no longer be configurable in the normal way , that is, you cannot con trol port features such as auto-negotiation, VLANs, static addresses, STP , Aggregated Links, Resilient Links, a nd so on.
62 C HAPTER 4: C REATING A S TACK Renumbering only occurs when the stack is next power cycled if the units are configur ed to auto-number . The unit LEDs will display the unit number in the stack, fr om 1 to 8. If you are having problems, r efer to “Solving Stack Formation Problems” on page 69 .
5 P RO B L E M S OLVING This chapter helps you to diagnose an d solve problems you may have with the operation of your Switch. There is also an explanation of IP addressing and upgrading software.
64 C HAPTER 5: P ROBLEM S OLVING Solving Problems Indicated by LEDs If the LEDs on the Switch indicate a problem, r efer to the list of su ggested solutions below . The PWR LED does not light Check that the power cable is firmly connected to the Switch and to the supply outlet.
Solving Hardware Problems 65 Auto-negotiation problems will occur with 10BASE-T or 100BASE-T where auto-negotiation is disabled a nd incorr ect cables are being used (cross-over or straight) Auto-nego.
66 C HAPTER 5: P ROBLEM S OLVING 3 Power cycle the unit. T o do this, remove and reconnect the AC mains supply . If the unit has no AC main supply , remove and r econnect the DC RPS supply . 4 If another fan failur e warn ing messa ge is generated via the Command Line Interface or the Web interfa ce, return the unit to 3Com.
Solving Communication Problems 67 Solving Communication Problems If you experience communication problems with the Switch, ensur e that: ■ The Switch IP address and Management VLAN ID has been configured.
68 C HAPTER 5: P ROBLEM S OLVING If your IP network is inter nal to your organization only , that is, you do not access the Inter net, you may use any arbitrary IP address as long as it is not being used by another device on your network. 3Com suggests you use addresses in the range 192.
Solving Stack Formation Problems 69 Solving Stack Formation Problems If you are having pr oblems with correctly forming a stack, first ensure that Spanning T r ee is enabled. If i t is enabled, do the following: 1 Power off all units in the stack. 2 Check all the cable connection s in the stack.
70 C HAPTER 5: P ROBLEM S OLVING.
6 U PGRADING S OFTWAR E This chapter describes how to upgrade software to your Switch 450 0. It covers the following topics: ■ The Contents of the Exe cutable File ■ Upgrading from the Command Lin.
72 C HAPTER 6: U PGRADING S OFTWARE The Contents of the Executable File The self extracting ex ecutable file (xxxxxxxx.exe — wher e xxxxxxxx is the file name of your Switch) contains the following :.
Upgrading from the Command Line Interface 73 A file list similar to the following is displayed: Directory of unit1>flash:/ 15367 KB total (10215 KB free) 2 Y ou can check the contents of the flash .
74 C HAPTER 6: U PGRADING S OFTWARE T o check that deleted files have be en r emoved from the r ecycle-bin for the remaining units in a fabric, r eplace unit1 with unit2 and so on for each Switch in the fabric.
Upgrading from the Command Line Interface 75 3 T o download the default configuration file, enter: tftp aaa.aaa.aaa.aaa get 3ComOScfg.def 4 T o download the bootrom file, enter: tftp aaa.aaa.aaa.aaa get s3o002_012_000.btm The bootrom firmware may not require upgrading for ever y software upgrade, therefore there may not be a new bootrom (.
76 C HAPTER 6: U PGRADING S OFTWARE T o set the r e maining Switches in the fabric to boot from the new so f tw a re , re p l ac e unit1 with unit2 and so on for each Switch in the fabric. 2 T o set the Switch to load the n ew bootr om firmwar e, enter: boot bootrom unit1>flash:/s3o002_012_000.
Upgrading from the Command Line Interface 77 200 PORT command successful. 150 Opening ASCII mode data connection for vrpcfg.def(10986 bytes).......226 Transfer complete. FTP: 10986 byte(s) received in 8.046 second(s) 1000.00 byte(s)/sec. 3 Enter quit to exit .
78 C HAPTER 6: U PGRADING S OFTWARE Upgrading from the Bootrom Interface This section describes how to upgr ade your Switch from the Bootrom Interface. Introduction When the Switch is running the init ial boot phase via the console, the following prompt is displayed with a five second countdown timer: Press CTRL-B to enter Boot Menu.
Upgrading from the Bootrom Interface 79 3 Select option 3 from the Boot Menu. A file list similar to the following is displayed: Boot menu choice: 3 Free Space: 10469376 bytes The current application file is s3n03_01_00s168.
80 C HAPTER 6: U PGRADING S OFTWARE TF TP T o upgrade software to your Switch via TF TP , do the following: 1 From the Boot Menu, select option 1 (D ownload application file to flash) to display the following: 1. Set TFTP protocol parameter 2. Set FTP protocol parameter 3.
Upgrading from the Bootrom Interface 81 Server IP address: FTP User Name: FTP User Password: 3 Enter the file name, Switch IP address, Server IP address and F TP user name and password to display the .
82 C HAPTER 6: U PGRADING S OFTWARE Now please start transfer file with XMODEM protocol If you want to exit, Press <Ctrl+X> Loading...CCCCCCCCCCCCCCCCCCCCCCCCCCCCC 5 As the file is d ownloading , start the XM odem send file p roce ss with terminal emulation software, su ch as Microsoft Hyperterminal.
Bootrom Upgrade 83 Bootrom Upgrade via TF TP T o upgrade the bootr om firmware fr om the Boot menu via TF TP do the following: 1 From the Boot menu, select option 6 to display the b ootrom upgrade menu as shown: Bootrom update menu: 1. Set TFTP protocol parameter 2.
84 C HAPTER 6: U PGRADING S OFTWARE Load File name: Switch IP address: Server IP address: FTP User Name: FTP User Password: 3 Enter the file name, Switch IP addr ess, Server IP address, F TP user name.
Bootrom Upgrade 85 4 Press Enter to start the download. The following informat ion is displayed: Now please start transfer file with XMODEM protocol If you want to exit, Press <Ctrl+X> Loading .
86 C HAPTER 6: U PGRADING S OFTWARE.
A P IN - OUTS Null Modem Cable RJ-45 to RS-232 25-pin PC-A T Serial Cable RJ-45 to 9-pin Screen TxD RxD Ground RTS CTS DSR DCD DTR Screen RxD TxD Ground RTS DTR CTS DSR DCD Shell 3 2 5 7 8 6 1 4 1 3 2.
88 A PPENDIX A: P IN - OUTS Modem Cable RJ-45 to RS-232 25-pin Ethernet Port RJ-45 Pin Assignments 10/100 and 1000BASE-T RJ- 45 connections. Ta b l e 10 Pin assignments Screen TxD RxD RTS CTS DSR Grou.
Ethernet Port RJ-45 Pin Assignments 89 Ta b l e 11 Pin assignments Pin Number 10/ 100 1000 Ports configured as MDIX 1 Receive Data + Bidirection al Data B+ 2 Receive Data - Bidirectional Data B- 3 Tra.
90 A PPENDIX A: P IN - OUTS.
B T ECHNICAL S PECIFICATIONS Switch 4500 (26 Port) Physical Dimensions Height: 44 mm (1.7 in.) x Width: 440 mm (17.3 in.) x Depth: 274 mm (10.8 in.) Weight: 4.
92 A PPENDIX B: T ECHNICAL S PECIFICATIONS Switch 4500 (50 Port) Physical Dimensions Height: 44 mm (1.7 in.) x Width: 440 mm (17.3 in.) x Depth: 274 mm (10.
Switch 4500 PWR (2 6 Port) 93 Switch 4500 PWR (26 Port) Physical Dimensions Height: 44 mm (1.7 in.) x Width: 440 mm (17.3 in.) x Depth: 274 mm (10.8 in.
94 A PPENDIX B: T ECHNICAL S PECIFICATIONS Switch 4500 PWR (50 Port) Physical Dimensions Height: 44 mm (1.7 in.) x Width: 440 mm (17.3 in.) x Depth: 274 mm (10.
RPS 95 RPS Earthing Lead Standards Supported SNMP SNMP protocol (RFC 1157) MIB-II (RFC 1213) Bridge MIB (RFC 1493) RMON MIB II (RFC 2021) Remote Monitoring MIB (RFC 1757) MAU MIB (RFC 2239) MIB II Tra.
96 A PPENDIX B: T ECHNICAL S PECIFICATIONS.
C O BTAINING S UPPORT FOR YOUR P R ODUCT Register Y our Product W arranty and other service benefits start from the date of purchase, so it is important to register your product quickly to ensure you get full use of the warranty and other service benefits available to you.
98 A PPENDIX C: O BTAINING S UPPORT FOR YOUR P RODUCT T r oubleshoot Online Y ou will find support tools posted on the 3Com web site at http://www.3com.com/ 3Com Knowledgebase helps you troubleshoot 3Com products. This query-based interactive tool is located at http://knowledgebase.
Contact Us 99 T o send a pr oduct directly to 3Com for repair , you must first obtain a return authorization number (RMA). Products sent to 3Com, without authorization numbers clearly marked on the outside of the package, will be returned to the sender unopened, at the sender’ s expense.
100 A PPENDIX C: O BTAINING S UPPORT FOR YOUR P RODUCT Austria Belgium Denmark Finland France Germany Hungary Ireland Israel Italy 01 7956 7124 070 700 770 7010 7289 01080 2783 0825 809 622 01805 404 747 06800 12813 1407 3387 1800 945 379 4 199 161346 Luxembourg Netherlands Norway Poland Portugal South Africa Spain Sweden Switzerland U.
I NDEX 101 I NDEX A access levels of default us ers 56 automatic setup 49 3Com Network Director 50 console port 50 B browsers choosing 54 C cable pin-outs 87 command line interface management 38 conso.
102 I NDEX power 19 specifications, system 91 SSH 53 Switch automatic setup 49 Switch 4500 dimensions 91 features 13 power socket 19 powering-up 32 size 91 weight 91 XRN Distributed Fabric 59 system s.
An important point after buying a device 3Com Switch 4500 26-Port (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought 3Com Switch 4500 26-Port yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data 3Com Switch 4500 26-Port - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, 3Com Switch 4500 26-Port you will learn all the available features of the product, as well as information on its operation. The information that you get 3Com Switch 4500 26-Port will certainly help you make a decision on the purchase.
If you already are a holder of 3Com Switch 4500 26-Port, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime 3Com Switch 4500 26-Port.
However, one of the most important roles played by the user manual is to help in solving problems with 3Com Switch 4500 26-Port. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device 3Com Switch 4500 26-Port along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
