Instruction/ maintenance manual of the product 128L ZyXEL Communications
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Prestige 128L User’s Manual Version 1.0 ZyXEL A CCESSING I NTERNET & I NTRANET.
ii ZyXEL Limited Warranty ZyXEL warrants to the original end user (purchaser) that this product is free from any defects in materials or workmanship for a period of up to two (2) years from the date of purchase.
iii you specific legal rights, and you may also have other rights which vary from state to state. Copyright © 1997 by ZyXEL The contents of this book may not be reproduced (in any part or as a whole) or transmitted in any form or by any means without the written permission of the publisher.
iv limits are designed to provide reasonable protection against harmful interference in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy, and if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
v company. The equipment must also be installed using an acceptable method of connection. In some cases, the company’s inside wiring associated with a single line individual service may be extended by means of a certified connector assembly.
vi Outside North America, you can dial +886 - 3 - 5783942 EXT 252 between 8:00AM and 5:00PM Taiwan time (GMT +8:00). • Fax : ZyXEL in North America: (714) 693 - 8811 or Taiwan: +886 - 3 - 5782439 • E - mail : • Sales inquiries : sales@zyxel.com in North America.
vii Contents ZyXEL Limited Warranty ............................................................ ii Copyright © 1997 by ZyXEL ...................................................... iii Acknowledgments .................................................
viii Collecting General Setup Information ...........................................9 Collecting IDSL Information ........................................................9 Collecting Ethernet Setup Information ........................................
ix 6 TCP/IP Configuration ........................................... 45 IP Subnet Mask .........................................................................45 LAN - to - LAN Application ..........................................................46 Remote Node Setup .
x About SNMP ..............................................................................79 Configuring Your Prestige For SNMP Support ........................79 11 System Security ................................................... 83 Configuring the SMT Password .
xi 15 Index .................................................................. 101.
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Introduction 1 1 Introduction Congratulations on your purchase of the ZyXEL Prestige 128L IDSL Router. The Prestige integrates a Router and Bridge, offering inexpensive yet complete telecommunications and internetworking solutions for your home or branch office.
2 Introduction ISDN Digital Subscriber Line (IDSL) IDSL uses the 2B1Q line coding standard for ISDN BRI circuits. Used for data - only applications, IDSL can use unshielded twisted pair wire for transmitting data at 64/128Kbps for up to 18,000 feet. The di fferences between IDSL and ISDN are: 1.
Introduction 3 Data Compression The Prestige incorporates Stac data compression and Compression Control Protocol. Applications For Your Prestige Some applications for your Prestige include: Internet Access The Prestige suppor ts TCP/IP protocol. It is also compatible with other IDSL access servers manufactured by vendors such as Ascend.
4 Introduction • Release notes for firmware upgrades and other information can be accessed through a ZyXEL FTP server site. For ZyXEL contact information see page v . Packing List Before you proceed further, check all items you received with your Prestige 128L against this list to make sure nothing is missing.
Introduction 5 • IDSL service provided by local phone company (optional). • An Ethernet connection to your computer. • A computer equipped with communications software configured to the following parameters: • VT100 terminal emulation. • 9600 Baud rate.
6 Introduction.
Before You Begin 7 2 Before You Begin To ensure successful installation of your Prestige, we strongly recommend that you carefully follow the steps outlined in Chapters 2 and 3 . These chapters are designed as a guide for you to collect all necessary information about your LAN.
8 Before You Begin Figure 2 - 1 Installation Guide Completing the Worksheet Before you continue, locate the worksheet at the end of thi s chapter. This information worksheet has been provided to help you get through setup and installation of your Prestige as easily as possible.
Before You Begin 9 Collecting General Setup Information Your Prestige requires the fol lowing system information. You can obtain all the pertinent information from your network administrator. Record this information into the worksheet as it becomes available.
10 Before You Begin Collecting Ethernet Setup Information This section assumes that you are setting up your Prestige for a TCP/IP connection. If you want to configure the Prestige for other protocols (e.
Before You Begin 11 IP Subnet Mask Number of Host Number of Bits 255.255.255.0 254 24 255.255.255.128 126 25 255.255.255.192 62 26 255.255.255.224 30 27 255.
12 Before You Begin Prestige Setup and Installation Worksheet General Setup Information • System Name (for identification purposes): _______________________________________ • Protocol Routing: ___.
Bef ore You Begin 13 ___UTP • IP Address: _______._______._______._______ • IP Subnet Mask: _______._______._______._______ Notes:.
14 Before You Begin.
Installation 15 3 Installation This chapter outlines how to connect your Prestige to the LAN and IDSL line. Refer to the diagram below to identify all of the ports on your device when you attempt to make the various connections.
16 Installation Connecting Your Computer and Your Prestige For the initial setup of your Prestige, use the provided RS - 232 cable and communications software to configure your Prestige. After your Prestige has been successfully installed, you can modify the configuration through a remote Telnet connection.
Installation 17 The UTP port is used to connect to a 10Base - T network. 10Base - T networks use Unshielded Twisted Pair (UTP) cable and RJ - 45 connectors that look like a bigger telephone plug with 8 pins.
18 Installation Figure 3 - 2 Front Panel PWR - Comes on as soon as you connect your Prestige to the power supply and switch it to the I (on) position. TST - Should be blinking if your Prestige is functioning properly. Line: LNK - Indicates that your Prestige has an ISDN line connected to the WAN interface and it has been successfully initialized.
Installation 19 Figure 3 - 3 Power on Messages If you press ENTER , your Prestige will display a login screen and ask you to enter the password as shown below: Figure 3 - 4 Login Screen Enter the default password, 1234 to get into the Main Menu of System Management Terminal (SMT ).
20 Installation Navigating Through the System Management Terminal Interface Use the SMT to configure your Prestige. Several operations that you should be familiar with before you attempt to modify the configuration are listed below: • Moving Forward to Another Menu.
Installation 21 • Saving Your Configuration. You can save your configuration by pressing ENTER at the message: Press ENTER to confirm or ESC to cancel: Saving the data on the screen will take you in most cases to the previous menu.
22 Installation # Menu Title Description Remote Nodes. 12 Static Routing Setup Setup static route for different protocols. There are four static routes for each protocol. 21 Filter Set Configuration Setup filters to be used in Menu 3 and Menu 11 to provide security, call control, etc.
Installation 23 1. System Name - Choose a descriptive name for identification purposes, e.g., p128l. This name should be no more than 8 alphanumeric characters.
24 Installation 1. Service Type - There are two options: Client or Server. Server provides clock to synchronize signals transmitted on the line. 2. Transfer Type - There are two options: Leased 128K or Leased 64K, which deci de the IDSL line’s baud rate.
Installation 25 General Ethernet Setup This menu determines the type of Ethernet interface you are using as well as the filter sets you wish to implement to monitor your Ethernet traffic. From Menu 3 - Ethernet Setup, enter 1 to go to menu 3.1 - General Etherne t Setup.
26 Installation network (looks like a bigger telephone plug). Determine which type you are using and select the appropriate option. 2. Input and Output Filter Sets - Filter sets are used to block certain packets to reduce traffic and to prevent a security breach.
Installation 27 will act as a DHCP server, capable of automatically assigning IP addre sses to Windows 95, Windows NT, and other systems that support the DHCP client. When DHCP is used, the following four items need to be set. Do not set this field to Server if there is already a DHCP server on your network.
28 Installation on the IP address that you assign. Unless you have special need for subnetting, use the default subnet mask calculated by your Prestige. 7. RIP Direction - This parameter determines how your Prestige handles RIP (Routing Information Protocol ).
Installation 29 When you are finished, press ENTER at the message: Press ENTER to Confirm... to save your selections, or press ESC at any time to cancel them. Novell IPX Ethernet Setup Refer to the chapter on Novell IPX configuration. Bridge Ethernet Setup Refer to the chapter on Bridging configuration.
30 Installatio n.
Configuring for Internet Access 31 4 Configuring for Internet Access Menu 4 of the SMT allows you to configure Internet access on one screen. Before you configure your Prestige for Internet access, you need to collect the following information from your ISP (Internet Service Provider).
32 Configuring for Internet Access IP Addresses and the Internet Conventionally, the Internet (with a capital I) refers the large - scale interconnected networks across the world that was originally developed by the US Department of Defense. The Internet uses exclusively the TCP/IP suite of protocols.
Configuring for Internet Access 33 A LLOCATION FOR P RIVATE I NTERNET ’ S AND RFC 1466, G UIDELINES FOR M ANAGEMENT OF IP A DDRESS S PACE . Once you have determined the IP address range for your loc.
34 Configuring for Internet Access 3. ISP IP Addr - Enter the IP Address of the remote gateway at the ISP’s site. If you do not have this data, just leave it blank. 4. My Login Name - Enter the login name provided by your ISP. 5. My Password - Enter the p assword associated with the login name above.
Configuring for Internet Access 35 This feat ure may also be used to connect to TCP/IP remote nodes other than Internet Service Providers. For example this feature can be used to simplify the allocation of IP addresses when connecting branch offices to the corporate network.
36 Configuring for Internet Access • UDP and TCP datagrams can be routed. In addition, ICMP echo can also be routed. The figure below shows an example of a small office connected to the Internet via a Single User Account using your Prestige.
Configuring for Internet Access 37 static IP address enter that IP address here. You have to use a static IP address if you are using a pair of Prestiges. 3. Si ngle User Account : Server IP Addr - If you want to make a single server, e.g., a Web server, accessible to outside users, enter that server’s IP address here.
38 Configuring for Intern et Access.
Remote Node Configuration 39 5 Remote Node Configuration A Remote Node represents both a remote gateway and the internet behind it, across an IDSL connection. A Remote Node is required for connecting to the remote network directly. Note that when you use Menu 4 to configure the Internet, your Prestige will automatically add a Remote Node for you.
40 Remote Node Configuration Figure 5 - 1 Menu 11 - Remote Node Setup Enter the Remote Node number to edit and you will go to the next submenu: 11.1 - Remote Node Profile as shown below: Figure 5 - 2 Menu 11.1 - Remote Node Profil e 1. Rem Node Name - This is a required field.
Remote Node Configuration 41 2. Active - Press the space bar to toggle between Yes and No. When a Remote Node is deactivated, it has no effect on the operation of your Prestige, even though it is still kept in the database and can be activated in the future.
42 Remote Node Configuration • CHAP /PAP - Your Prestige will try CHAP when CHAP is requested by the Remote Node or PAP when PAP is requested by the Remote Node. • CHAP - Use CHAP only. • PAP - Use PAP only. 8. Route - This field determines the protocols that your Prestige will route.
Remote Node Configuration 43 and your Prestige. You can choose from 12 different filter sets. In addition, you can link up to 4 filter sets together for further customization (e.g., 1, 5, 9, 12). Note that spaces and , are accepted in this field. For more information on customizing your filter sets, see Chapter 9.
44 Remote Node Configuration 2. Compression - Turns on Stac Compression. The default for this field is Off. Once you have completed Menu 11.2 - Remote Node PPP Op tions, press ENTER at the message: Press ENTER to Confirm ... to confirm your selections, or press ESC to cancel your selections.
TCP/IP Configuration 45 6 TCP/IP Configuration This chapter shows you how to configure your Prestige for TCP/IP . Depending on your particular applications, you will need to configure different menus. For instance, Internet access is the most common application of TCP/IP.
46 TCP/IP Configuration to partition your class C network 204.247.203.0 with subnet mask 255.255.255.0 into 16 subnets (4 bits), the new subnet mask becomes 255.
TCP/IP Configuration 47 configure Static Routes if some services reside beyond the immediate remote LAN . Remote Node Setup Follow the procedure in Chapter 5 to fill the protocol - independent parameters in Menu 11, Remote Node Profi le. For the protocol - dependent parameters, follow the instructions below.
48 TCP/IP Configurat ion 2. Rem IP Subnet Mask - Enter the subnet mask for the remote network. 3. My WAN Addr - Some implementations, especially the UNIX derivatives, require hosts on both ends of the ISDN lin k to have separate addresses from the LAN , and that the addresses must have the same network number.
TCP/IP Configuration 49 not be pr ecise, but it must be between 1 and 16. In practice, 2 or 3 is usually a good number. 7. Private - This parameter determines if your Prestige will include the route to this Remote Node in its RIP broadcasts. If set to yes, this route is kept private and not included in RIP broadcast.
50 TCP/IP Configuration or a Remote Node , a static route is implicitly created by your Prestige. An example is given below. In the example, stations on the 204.5.1.0/24 subnet work can access the remote stations using the static route. The route will have a destination of 204.
TCP/IP Configuration 51 Figure 6 - 5 Menu 12 - Static Route Setup - Main Menu Figure 6 - 6 IP Static Route Setup 1. Route Name - Enter a descriptive name for this route. This is for identification purpose only. 2. Active - This fields allows you to activate/deactivate this static route.
52 TCP/IP Configuration use a subnet mask of 255.255.255.255 in the subnet mask field to force the network number to be identical to the host ID. 4. IP Subnet Mask - Enter the subnet mask for this destination. Follow the discussion on IP subnet mask in this chapter.
Novell IPX Configuration 53 7 Novell IPX Configuration This chapter shows you how to configure your Prestige for IPX . Depending on your particular applications, you will need to configure different menus. We will illustrate the configuration for some applications in the following sections.
54 Novell IPX Configuration Figure 7 - 1 Prestige Operating in IPX Environment Prestige on LAN with Server When your Prestige is being connected to a LAN with an existing NetWare server station, you will not need to configure it as a seed router, and hence the network number parameter in the Ethernet Setup Menu.
Novell IPX Configuration 55 IPX Ethernet Setup The first step is to set up your Prestige on the LAN . From menu 3, select option 3 to go to Menu 3.3 - Novell IPX Ethernet Setup as seen below: Figure 7 - 2 Menu 3.3 - Novell IPX Ethernet Setup 1. Seed Router - Determine if your Prestige is to act as a seed router.
56 Novell IPX Configuration • SNAP 3. IPX Network # - If you selected your Prestige to act as a seed router, you need to prov ide a unique network number to be associated with the network that it has joined. Keep in mind that this number must not be used anywhere else on the network.
Novell IPX Configuration 57 Remote Node Setup Follow the procedure in Chapter 5 to fill the protocol - independent parameters in Menu 11, Remote Node Profile. For the protocol - dependent parameters, follow t he ensuing instructions. 1. Route - Make sure IPX is among the protocols in the Route field.
58 Novell IPX Configuration 6. Tick Count - This field indicates the time - ticks required to reach the Remote Node . The default is two (2). 7. W/D Spoofing (min) - This field is used for your Prestige on the server side LAN . Your Prestige can spoof a response to a server’s Watch Dog request after an expected drop of connection.
Novell IP X Configuration 59 Figure 7 - 5 NetWare Servers on Both Sides of the Link This may present a problem if you desire your client station to access a server at a r emote site.
60 Novell IPX Configuration Figure 7 - 6 Menu 12.2 - Edit IPX Static Route 1. Server Name - In this field, enter in the name that has been configured for the server. This name must be the exact name configured in the NetWare server. 2. Network # - This field contains the internal network number of the remote server which you wish to access.
Novell IPX Configuration 61 The Hop Count and Tick Count fields have the same meaning as those in the Remote Node Setup. Once you have completed filling in the menu, press ENTER at the message: Press ENTER to Confirm ... to save your selections, or press ESC at any time to cancel your selections.
62 Novell IPX Configuration.
Bridging Configuration 63 8 Bridging Configuration This chapter shows you how to configure the Bridging options for your Prestige. Depending on your particu lar applications, you will need to configure different menus. We will illustrate the configuration for some applications in the following sections.
64 Bridging Configuration Figure 8 - 7 Remote Node Bridging Configuration 3. Ethernet Addr Timeout (min) - In this field, enter the time (number of minutes) that you wish your Prestige to retain the Ethernet Addr information in its internal tables while the line is down.
Bridging Configuration 65 Figure 8 - 8 Menu 12.4 - Bridge Static Route 1. Route Name - For identification purp oses enter a name for the bridge static route. 2. Active - Indicates whether the static route is active or not. 3. Ether Address - Enter the MAC address of the destination device that you wish to bridge your packets to.
66 Bridging Configuration.
Filter Configuration 67 9 Filter Configuration About Filtering Your Prestige uses filters to decide whether or not to allow passage of a data packet and/or to make a call over the ISDN line. There are two types of filters involved: incoming data filters and outgoing da ta filters.
68 Filter Configuration Prestige’s Filter Structure You can configur e up to twelve filter sets with six rules in each set. Therefore, your Prestige allows you to customize up to 72 filter rules (12 x 6). When implementing these filter sets, you can link up to four of the filter sets together to screen the data packet.
Filter Configuration 69 Figure 9 - 2 Menu 21 - Filter Set Configuration Once you press ENTER, you will be taken to Menu - 21.1 - Filter Rules Summary as seen below. The information displayed in th is menu is read - only. From here, you can examine the parameters of each rule that you have configured for that set.
70 Filter Configuration • m - Refers to Action Matched. F means to forward the packet, D means to drop the packet, and N means check the next rule. • n - Refers to Action Not Matched. F means to forward the packet, D means to drop the packet, and N means check the next rule.
Filter Configuration 71 • PT - IPX Packet Type. • SS - Source Socket. • DS - Destination Socket. For more information on configuring th e filter rule parameters, refer to the next section. To configure a specific filter rule, simply select the number of the filter rule (1 - 6) you wish to configure and press ENTER.
72 Filter Configuration Figure 9 - 4 Menu 21.1.1 - TCP/IP Filter Rule 1. Active - In this field, you can make the filter rule active or inactive. There are two options: • Yes. • No. 2. IP Protocol - Protocol refers to the IP specific number of the protocol.
Filter Configuration 73 6. Destination: Port # - Enter the destination port of the packets that you wish to filter. The range of this field is 0 to 65535. 7. Destination: Port # Comp - In this field, you can select what comparison quantifier you wish to enable to compare to the value given in Destination: Port #.
74 Filter Configuration (TCP protocol). In this field you determine what type of TCP packets to filter. There are two options: • Yes - filter matches only established TCP co nnections. • No - filter matches both initial and established TCP connections .
Filter Configuration 75 16. Action Not Matched - If the conditions for the filter rule are not met, you can specify what to do with the packet. There are three options for this field: • Check Next Rule . • Forward. • Drop. Once you have completed filling in Menu 21.
76 Filter Configuration 1. Offset - Offset refers to the value of the byte that you want to use as your starting offset. That is, i n the data packet, at what point do you want to begin the comparison. The range for this field is from 0 to 255. Default = 0 2.
Filter Configuration 77 Novell IPX Filter Rule This section will show you how to configure the protocol - dependent param eters for an IPX filter. The fields in the menu are displayed in bold type. Figure 9 - 6 Menu 21.1.3 - IPX Filter Rule 1. IPX Packet Type - Enter the IPX packet type value of the packet you wish to filter.
78 Filter Configuration 6. Operation - This field is only active if one of the Socket # fields is 0452 or 0453 indicating SAP and RIP packets. There are seven options for this field which determines the operation for the IPX packet. • None. • RIP Request.
SNMP 79 10 SNMP About SNMP The Simple Network Management Protocol (SNMP ) is a protocol governing network management and the monitoring of network devices and their functions. The Prestige 128L supports the utilization of SNMP to regulate the communication that occurs between the manager station and the agent stations in a network.
80 SNMP Figure 10 - 1 Menu 22 - SNMP Configuration 1. From the Main Menu, select option 22. SNMP Confi guration. This will bring you to Menu 22 - SNMP Configuration. 2. You will then be prompted to enter the following information. Steps 3 - 7 will describe the specific parameters involved in the configuration.
SNMP 81 leave the field blank (d efault), then your Prestige will respond to all SNMP messages it receives, regardless of origin. 6. Trap: Community - In this field, enter the community name that is sent with each trap to the SNMP manager. This should be treated like a password and match what the SNMP manager is expecting.
82 SNMP.
System Security 83 11 System Security The Prestige 128L incorporates a number of security measures to prevent unauthorized access to your network. For example, your Prestige supports both PAP (Password Authentication Protocol ) and CHAP (Challenge Handshake Authentication Protocol ) in authenticating a Remote Node .
84 System Securit y The following step s describe a simple setup procedure for configuring the SMT password. 1. From the Main Menu, select option 23. System Security. This will bring you to Menu 23 - System Security. 2. From this menu, you can select option 1.
Telnet Configuration and Capabilities 85 12 Telnet Configuration and Capabilities About Telnet Configuration When you first configure your Prestige, it must be done via a computer connected to the RS - 232 port.
86 Telnet Configuration and Capabilities management . If your Prestige is configured for IPX routing but not IP in menu 1, telnet will still be available provided you assign your Prestige an IP address.
System Maintenance 87 13 System Maintenance The Prestige 128L provides a full rang e of diagnostic tools to help you monitor and maintain your system. Some of these tools provide updates on system status, ISDN B channel status, log and trace capabilities and upgrades to system software.
88 System Maintenance Figure 13 - 2 Example of Menu 24.1 - System Maintenance - Status 1. To get to the System Status, select option 24. System Maintenance. This will bring you to Menu 24 - System Maintenance. 2. From this menu, select option 1. System Status.
System Maintenance 89 11. CLU - (C urrent Line Utilization) - percentage of current bandwidth used on this channel. 12. ALU - (Average Line Utilization) - average CLU for this channel. 13. Up Time - time this channel has been connected to the current Remote Node .
90 System Maintenance Figure 13 - 3 Menu 24.2 - System Maintenance - Change Terminal Baud Rate Log and Trace Log and trace tools allow you to view the error logs and trace records to troubleshoot any er rors that may occur. Your Prestige is also able to generate syslogs to send to other machines.
System Maintenance 91 View Error Log Selecting the first option from Menu 24.3 - System Maintenance - Log and Trace will display the system Error Log. The Error Log does not only provide the error messages but it is also a source of information about your Prestige.
92 System Maintenance 2. Syslog IP Address - Input the IP Address that you wish to send your syslog to. The address is usually written in dotted decimal notation such as a.b.c.d where a, b, c, and d are numbers betwee n 0 and 255. 3. Log Facility - Use the space bar to toggle between the 7 different Local options.
System Maintenance 93 3. Items 4 - 7 will describes the four (4) options to test your Prestige and its connections. 4. Internet Setup Test - This test checks to see if y our Internet access configuration has been done correctly. When this option is chosen, your Prestige will PING the Internet IP Address.
94 System Maintenance Restore Configuration Selecting option 6 from Menu 24 - Maintenance will restore backup configuration from disk to your Prestige.
System Maintenanc e 95 Figure 13 - 6 Example of uploading RAS using PCPLUS Command Interpreter Mode This option allows the user to enter the command interpreter mode. This mode allows you t o diagnose, test, and configure your Prestige using a specified set of commands.
96 System Maintenance.
Troubleshooting 97 14 Troubleshooting This chapter contains some problems you may run into when using your Prestige. After each problem description, we have provided some instructions to help you diagnose and solve the problem.
98 Troubleshooting Problems With the IDSL Line The IDSL LEDs Not On Check the connection between your two routers. When they are connected, the link and B1/B2 LED should be on if the transfer type is leased 128; and the link and B1 LED are on if the transfer type is leased 64.
Troubleshooting 99 Problems Connecting to a Remote Node or ISP 1. Check menu 24.1 to verify the IDSL status. If it is down then refer to the section on the IDSL line problems. 2. If you check the error log in menu 24.3.1, this will usually give you some logs regarding where goes wrong.
100 Troubleshooting.
Index 101 15 Index 10Base2, 10, 17 10Base5. See AUI 10Base - T, 9, 10, 16, 17, 24 Accounting, 91 AUI, 10, 17, 25, 98 BNC. See 10Base2 Bridging, 1, 2, 9, 29, 42, 63, 64 Canadian User Information, iv Challenge Handshake Authentication Protocol.
102 Index RIP, 28, 49, 54, 58, 77, 78 Routing Information Protocol. See RIP RS - 232, iv, 2, 16, 17, 85, 86, 90, 94, 97 SAP, 58, 59, 77, 78 Simple Network Management Protocol. See SNMP Single User Account, 3, 34, 35, 36, 37 SMT, 19, 20, 21, 22, 31, 34, 83, 84, 97 SNMP, 2, 9, 22, 23, 79, 80, 81 Spoofing, 58 Stac, 3 SUA.
An important point after buying a device ZyXEL Communications 128L (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought ZyXEL Communications 128L 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 ZyXEL Communications 128L - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, ZyXEL Communications 128L you will learn all the available features of the product, as well as information on its operation. The information that you get ZyXEL Communications 128L will certainly help you make a decision on the purchase.
If you already are a holder of ZyXEL Communications 128L, 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 ZyXEL Communications 128L.
However, one of the most important roles played by the user manual is to help in solving problems with ZyXEL Communications 128L. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device ZyXEL Communications 128L 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
