ZyXEL EMG2881-T20A Users Manual
9.6 UPnP Screen
Use this screen to enable UPnP on your EMG2881-T20A.
Click Configuration > Applications > UPnP to display the screen shown next.
Figure 46 Configuration > Applications > UPnP
The following table describes the fields in this screen.
Table 37 Configuration > Applications > UPnP
LABEL DESCRIPTION
UPnP Select Enable to activate UPnP. Be aware that anyone could use a UPnP application to
Apply Click Apply to save the setting to the EMG2881-T20A.
Cancel Click Cancel to return to the previously saved settings.
Chapter 9 Applications
open the web configurator's login screen without entering the EMG2881-T20A's IP address
(although you must still enter the password to access the web configurator).
9.7 Technical Reference
The following section contains additional technical information about the EMG2881-T20A features
described in this chapter.
IEEE 802.1Q Tag
The IEEE 802.1Q standard defines an explicit VLAN tag in the MAC header to identify the VLAN
membership of a frame across bridges. A VLAN tag includes the 12-bit VLAN ID and 3-bit user priority.
The VLAN ID associates a frame with a specific VLAN and provides the information that devices need to
process the frame across the network.
IEEE 802.1p specifies the user priority field and defines up to eight separate traffic types. The following
table describes the traffic types defined in the IEEE 802.1d standard (which incorporates the 802.1p).
Table 38 IEEE 802.1p Priority Level and Traffic Type
PRIORITY
LEVEL
Level 7 Typically used for network control traffic such as router configuration messages.
Level 6 Typically used for voice traffic that is especially sensitive to jitter (jitter is the variations in delay).
Level 5 Typically used for video that consumes high bandwidth and is sensitive to jitter.
Level 4 Typically used for controlled load, latency-sensitive traffic such as SNA (Systems Network
Level 3 Typically used for “excellent effort” or better than best effort and would include important business
Level 2 This is for “spare bandwidth”.
TRAFFIC TYPE
Architecture) transactions.
traffic that can tolerate some delay.
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Table 38 IEEE 802.1p Priority Level and Traffic Type
PRIORITY
LEVEL
Level 1 This is typically used for non-critical “background” traffic such as bulk transfers that are allowed but
Level 0 Typically used for best-effort traffic.
TRAFFIC TYPE
that should not affect other applications and users.
DiffServ
QoS is used to prioritize source-to-destination traffic flows. All packets in the flow are given the same
priority. You can use CoS (class of service) to give different priorities to different packet types.
DiffServ (Differentiated Services) is a class of service (CoS) model that marks packets so that they
receive specific per-hop treatment at DiffServ-compliant network devices along the route based on the
application types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the
level of service desired. This allows the intermediary DiffServ-compliant network devices to handle the
packets differently depending on the code points without the need to negotiate paths or remember
state information for every flow. In addition, applications do not have to request a particular service or
give advanced notice of where the traffic is going.
DSCP and Per-Hop Behavior
DiffServ defines a new Differentiated Services (DS) field to replace the Type of Service (TOS) field in the IP
header. The DS field contains a 2-bit unused field and a 6-bit DSCP field which can define up to 64
service levels. The following figure illustrates the DS field.
DSCP is backward compatible with the three precedence bits in the ToS octet so that non-DiffServ
compliant, ToS-enabled network device will not conflict with the DSCP mapping.
DSCP (6 bits) Unused (2 bits)
The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior), that each packet
gets across the DiffServ network. Based on the marking rule, different kinds of traffic can be marked for
different kinds of forwarding. Resources can then be allocated according to the DSCP values and the
configured policies.
IP Precedence
Similar to IEEE 802.1p prioritization at layer-2, you can use IP precedence to prioritize packets in a layer-3
network. IP precedence uses three bits of the eight-bit ToS (Type of Service) field in the IP header. There
are eight classes of services (ranging from zero to seven) in IP precedence. Zero is the lowest priority
level and seven is the highest.
Automatic Priority Queue Assignment
If you enable QoS on the EMG2881-T20A, the EMG2881-T20A can automatically base on the IEEE 802.1p
priority level, IP precedence and/or packet length to assign priority to traffic which does not match a
class.
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The following table shows you the internal layer-2 and layer-3 QoS mapping on the EMG2881-T20A. On
the EMG2881-T20A, traffic assigned to higher priority queues gets through faster while traffic in lower
index queues is dropped if the network is congested.
Table 39 Internal Layer2 and Layer3 QoS Mapping
LAYER 2 LAYER 3
PRIORITY
QUEUE
IEEE 802.1P USER
PRIORITY
(ETHERNET
TOS (IP
PRECEDENCE)
DSCP
IP PACKET LENGTH
(BYTE)
PRIORITY)
0 1 0 000000
12
2 0 0 000000 >1100
3 3 1 001110
001100
001010
001000
4 4 2 010110
010100
010010
010000
5 5 3 011110
011100
011010
011000
6 6 4 100110
250~1100
<250
100100
100010
100000
5 101110
101000
7 7 6 110000
7
111000
Token Bucket
The token bucket algorithm uses tokens in a bucket to control when traffic can be transmitted. The
bucket stores tokens, each of which represents one byte. The algorithm allows bursts of up to b bytes
which is also the bucket size, so the bucket can hold up to b tokens. Tokens are generated and added
into the bucket at a constant rate. The following shows how tokens work with packets:
• A packet can be transmitted if the number of tokens in the bucket is equal to or greater than the size
of the packet (in bytes).
• After a packet is transmitted, a number of tokens corresponding to the packet size is removed from
the bucket.
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• If there are no tokens in the bucket, the EMG2881-T20A stops transmitting until enough tokens are
generated.
• If not enough tokens are available, the EMG2881-T20A treats the packet in either one of the following
ways:
In traffic shaping:
• Holds it in the queue until enough tokens are available in the bucket.
In traffic policing:
•Drops it.
• Transmits it but adds a DSCP mark. The EMG2881-T20A may drop these marked packets if the
network is overloaded.
Configure the bucket size to be equal to or less than the amount of the bandwidth that the interface
can support. It does not help if you set it to a bucket size over the interface’s capability. The smaller the
bucket size, the lower the data transmission rate and that may cause outgoing packets to be dropped.
A larger transmission rate requires a big bucket size. For example, use a bucket size of 10 kbytes to get
the transmission rate up to 10 Mbps.
Single Rate Three Color Marker
The Single Rate Three Color Marker (srTCM, defined in RFC 2697) is a type of traffic policing that identifies
packets by comparing them to one user-defined rate, the Committed Information Rate (CIR), and two
burst sizes: the Committed Burst Size (CBS) and Excess Burst Size (EBS).
The srTCM evaluates incoming packets and marks them with one of three colors which refer to packet
loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and
low is referred to as green.
The srTCM is based on the token bucket filter and has two token buckets (CBS and EBS). Tokens are
generated and added into the bucket at a constant rate, called Committed Information Rate (CIR).
When the first bucket (CBS) is full, new tokens overflow into the second bucket (EBS).
All packets are evaluated against the CBS. If a packet does not exceed the CBS it is marked green.
Otherwise it is evaluated against the EBS. If it is below the EBS then it is marked yellow. If it exceeds the
EBS then it is marked red.
The following shows how tokens work with incoming packets in srTCM:
• A packet arrives. The packet is marked green and can be transmitted if the number of tokens in the
CBS bucket is equal to or greater than the size of the packet (in bytes).
• After a packet is transmitted, a number of tokens corresponding to the packet size is removed from
the CBS bucket.
• If there are not enough tokens in the CBS bucket, the EMG2881-T20A checks the EBS bucket. The
packet is marked yellow if there are sufficient tokens in the EBS bucket. Otherwise, the packet is
marked red. No tokens are removed if the packet is dropped.
Two Rate Three Color Marker
The Two Rate Three Color Marker (trTCM, defined in RFC 2698) is a type of traffic policing that identifies
packets by comparing them to two user-defined rates: the Committed Information Rate (CIR) and the
Peak Information Rate (PIR). The CIR specifies the average rate at which packets are admitted to the
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network. The PIR is greater than or equal to the CIR. CIR and PIR values are based on the guaranteed
and maximum bandwidth respectively as negotiated between a service provider and client.
The trTCM evaluates incoming packets and marks them with one of three colors which refer to packet
loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and
low is referred to as green.
The trTCM is based on the token bucket filter and has two token buckets (Committed Burst Size (CBS)
and Peak Burst Size (PBS)). Tokens are generated and added into the two buckets at the CIR and PIR
respectively.
All packets are evaluated against the PIR. If a packet exceeds the PIR it is marked red. Otherwise it is
evaluated against the CIR. If it exceeds the CIR then it is marked yellow. Finally, if it is below the CIR then
it is marked green.
The following shows how tokens work with incoming packets in trTCM:
• A packet arrives. If the number of tokens in the PBS bucket is less than the size of the packet (in bytes),
the packet is marked red and may be dropped regardless of the CBS bucket. No tokens are removed
if the packet is dropped.
• If the PBS bucket has enough tokens, the EMG2881-T20A checks the CBS bucket. The packet is
marked green and can be transmitted if the number of tokens in the CBS bucket is equal to or greater
than the size of the packet (in bytes). Otherwise, the packet is marked yellow.
9.7.1 Using UPnP in Windows XP Example
This section shows you how to use the UPnP feature in Windows XP. You must already have UPnP installed
in Windows XP and UPnP activated on the EMG2881-T20A.
Make sure the computer is connected to a LAN port of the EMG2881-T20A. Turn on your computer and
the EMG2881-T20A.
9.7.1.1 Auto-discover Your UPnP-enabled Network Device
1 Click start and Control Panel. Double-click Network Connections. An icon displays under Internet
Gateway.
2 Right-click the icon and select Properties.
Figure 47 Network Connections
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3 In the Internet Connection Properties window, click Settings to see the port mappings there were
automatically created.
Figure 48 Internet Connection Properties
4 You may edit or delete the port mappings or click Add to manually add port mappings.
Figure 49 Internet Connection Properties: Advanced Settings
Figure 50 Internet Connection Properties: Advanced Settings: Add
Note: When the UPnP-enabled device is disconnected from your computer, all port
mappings will be deleted automatically.
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5 Select Show icon in notification area when connected option and click OK. An icon displays in the
system tray.
Figure 51 System Tray Icon
6 Double-click on the icon to display your current Internet connection status.
Figure 52 Internet Connection Status
9.7.2 Web Configurator Easy Access
With UPnP, you can access the web-based configurator on the EMG2881-T20A without finding out the IP
address of the EMG2881-T20A first. This comes helpful if you do not know the IP address of the EMG2881T20A.
Follow the steps below to access the web configurator.
1 Click Start and then Control Panel.
2 Double-click Network Connections.
3 Select My Network Places under Other Places.
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Figure 53 Network Connections
Chapter 9 Applications
4 An icon with the description for each UPnP-enabled device displays under Local Network.
5 Right-click on the icon for your EMG2881-T20A and select Invoke. The web configurator login screen
displays.
Figure 54 Network Connections: My Network Places
6 Right-click on the icon for your EMG2881-T20A and select Properties. A properties window displays with
basic information about the EMG2881-T20A.
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Figure 55 Network Connections: My Network Places: Properties: Example
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10.1 Overview
Use these screens to enable and configure the firewall that protects your EMG2881-T20A and your LAN
from unwanted or malicious traffic.
Enable the firewall to protect your LAN computers from attacks by hackers on the Internet and control
access between the LAN and WAN. By default the firewall:
• allows traffic that originates from your LAN computers to go to all of the networks.
• blocks traffic that originates on the other networks from going to the LAN.
The following figure illustrates the default firewall action. User A can initiate an IM (Instant Messaging)
session from the LAN to the WAN (1). Return traffic for this session is also allowed (2). However other traffic
initiated from the WAN is blocked (3 and 4).
CHAPTER 10
Security
Figure 56 Default Firewall Action
10.1.1 What You Can Do
• Use the IPv4 Firewall screen to enable or disable the EMG2881-T20A’s IPv4 firewall (Section 10.2 on
page 93).
• Use the IPv6 Firewall screen to enable or disable the EMG2881-T20A’s IPv6 firewall (Section 10.3 on
page 95).
10.1.2 What You Need To Know
The following terms and concepts may help as you read through this chapter.
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About the EMG2881-T20A Firewall
The EMG2881-T20A’s firewall feature physically separates the LAN and the WAN and acts as a secure
gateway for all data passing between the networks.
It is a stateful inspection firewall and is designed to protect against Denial of Service attacks when
activated (click the IPv4 Firewall or IPv6 Firewall tab under Security and then click the Enable Firewall
check box). The EMG2881-T20A's purpose is to allow a private Local Area Network (LAN) to be securely
connected to the Internet. The EMG2881-T20A can be used to prevent theft, destruction and
modification of data, as well as log events, which may be important to the security of your network.
The EMG2881-T20A is installed between the LAN and a broadband modem connecting to the Internet.
This allows it to act as a secure gateway for all data passing between the Internet and the LAN.
The EMG2881-T20A has one Ethernet WAN port and four Ethernet LAN ports, which are used to physically
separate the network into two areas.The WAN (Wide Area Network) port attaches to the broadband
(cable or DSL) modem to the Internet.
The LAN (Local Area Network) port attaches to a network of computers, which needs security from the
outside world. These computers will have access to Internet services such as e-mail, FTP and the World
Wide Web. However, "inbound access" is not allowed (by default) unless the remote host is authorized to
use a specific service.
Guidelines For Enhancing Security With Your Firewall
1 Change the default password via Web Configurator.
2 Think about access control before you connect to the network in any way, including attaching a
modem to the port.
3 Limit who can access your router.
4 Don't enable any local service (such as NTP) that you don't use. Any enabled service could present a
potential security risk. A determined hacker might be able to find creative ways to misuse the enabled
services to access the firewall or the network.
5 For local services that are enabled, protect against misuse. Protect by configuring the services to
communicate only with specific peers, and protect by configuring rules to block packets for the services
at specific interfaces.
6 Protect against IP spoofing by making sure the firewall is active.
7 Keep the firewall in a secured (locked) room.
10.2 IPv4 Firewall Screen
Use this screen to enable or disable the EMG2881-T20A’s IPv4 firewall. Click Configuration > Security >
IPv4 Firewall to open the firewall setup screen.
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Figure 57 Configuration > Security > IPv4 Firewall
The following table describes the labels in this screen.
Table 40 Configuration > Security > IPv4 Firewall
LABEL DESCRIPTION
ICMP Internet Control Message Protocol is a message control and error-reporting protocol between
Respond to Ping onThe EMG2881-T20A will not respond to any incoming Ping requests when Disable is selected.
Firewall Setup
Enable Firewall Select this check box to activate the firewall. The EMG2881-T20A performs access control and
Enable Firewall Rule
Enable Firewall
Rule
Filter table type Select DROP to silently discard the packets which meet the firewall rules. The others are
Add Firewall Rule
Service Name Enter a name that identifies or describes the firewall rule.
MAC Address Enter the MAC address of the computer for which the firewall rule applies.
a host server and a gateway to the Internet. ICMP uses Internet Protocol (IP) datagrams, but
the messages are processed by the TCP/IP software and directly apparent to the application
user.
Select LAN to reply to incoming LAN Ping requests. Select WAN to reply to incoming WAN Ping
requests. Otherwise select LAN&WAN to reply to all incoming LAN and WAN Ping requests.
protects against Denial of Service (DoS) attacks when the firewall is activated.
Select this check box to activate the firewall rules that you define (see Add Firewall Rule
below).
accepted.
Select ACCEPT to allow the passage of the packets which meet the firewall rules. The others
are blocked.
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Table 40 Configuration > Security > IPv4 Firewall (continued)
LABEL DESCRIPTION
Dest IP Address Enter the IP address of the computer to which traffic for the application or service is entering.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
Source IP Address Enter the IP address of the computer that initializes traffic for the application or service.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
Protocol Select the protocol (TCP, UDP or ICMP) used to transport the packets for which you want to
Dest Port Range This is the port number/range of the destination that define the traffic type, for example TCP
Source Port Range This is the port number/range of the source that define the traffic type, for example TCP port
Add Rule Click Add Rule to save the firewall rule.
Firewall Rule
# This is your firewall rule number. The ordering of your rules is important as rules are applied in
Service Name This is a name that identifies or describes the firewall rule.
MAC address This is the MAC address of the computer for which the firewall rule applies.
Dest IP This is the IP address of the computer to which traffic for the application or service is entering.
Source IP This is the IP address of the computer from which traffic for the application or service is
Protocol This is the protocol (TCP, UDP or ICMP) used to transport the packets for which you want to
Dest Port Range This is the port number/range of the destination that define the traffic type, for example TCP
Source Port Range This is the port number/range of the source that define the traffic type, for example TCP port
Delete Click to remove the firewall rule.
Apply Click Apply to save the settings.
Cancel Click Cancel to start configuring this screen again.
apply the firewall rule.
port 80 defines web traffic.
80 defines web traffic.
turn.
initialized.
apply the firewall rule.
port 80 defines web traffic.
80 defines web traffic.
10.3 IPv6 Firewall Screen
This chapter shows you how to enable and create IPv6 firewall rules to filter IPv6 traffic.
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Click Configuration > Security > IPv6 Firewall. The IPv6 Firewall screen appears as shown.
Figure 58 Configuration > Security > IPv6 Firewall
The following table describes the labels in this screen.
Table 41 Configuration > Security > IPv6 Firewall
LABEL DESCRIPTION
Enable Firewall Rule
Enable Firewall Rule Select this check box to activate the firewall rules that you define (see Add Firewall Rule
below).
Filter table type Select DROP to silently discard the packets which meet the firewall rules. The others are
accepted.
Select ACCEPT to allow the passage of the packets which meet the firewall rules. The others
are blocked.
Add Firewall Rule
Service Name Enter a name that identifies or describes the firewall rule.
MAC Address Enter the MAC address of the computer for which the firewall rule applies.
Dest IP Address Enter the IPv6 address of the computer to which traffic for the application or service is
Source IP Address Enter the IPv6 address of the computer that initializes traffic for the application or service.
Protocol Select the protocol (TCP, UDP or ICMPv6) used to transport the packets for which you want
Dest Port Range Enter the port number/range of the destination that defines the traffic type, for example
Source Port Range Enter the port number/range of the source that defines the traffic type, for example TCP
Add Rule Click Add Rule to save the firewall rule.
Firewall Rule
entering.
The EMG2881-T20A applies the firewall rule to traffic destined for this computer.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
to apply the firewall rule.
TCP port 80 defines web traffic.
port 80 defines web traffic.
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Table 41 Configuration > Security > IPv6 Firewall (continued)
LABEL DESCRIPTION
# This is your firewall rule number. The ordering of your rules is important as rules are applied in
turn.
ServiceName This is a name that identifies or describes the firewall rule.
MAC Address This is the MAC address of the computer for which the firewall rule applies.
Dest IP This is the IP address of the computer to which traffic for the application or service is
Source IP This is the IP address of the computer to which traffic for the application or service is
Protocol This is the protocol (TCP, UDP or ICMPv6) used to transport the packets for which you want to
Dest Port Range This is the port number/range of the destination that defines the traffic type, for example
Source Port Range This is the port number/range of the source that defines the traffic type, for example TCP
Delete Click to remove the firewall rule.
Apply Click Apply to save the settings.
Cancel Click Cancel to restore your previously saved settings.
entering.
initialized.
apply the firewall rule.
TCP port 80 defines web traffic.
port 80 defines web traffic.
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11.1 Overview
This chapter provides information on the Maintenance screens.
11.2 What You Can Do
• Use the General screen to set the timeout period of the management session (Section 11.3 on page
98).
• Use the Password screen to change your EMG2881-T20A’s system password (Section 11.4 on page
99).
• Use the Time screen to change your EMG2881-T20A’s time and date (Section 11.5 on page 100).
• Use the Firmware Upgrade screen to upload firmware to your EMG2881-T20A (Section 11.6 on page
101).
• Use the Backup/Restore screen to view information related to factory defaults, backup configuration,
and restoring configuration (Section 11.8 on page 104).
• Use the Restart screen to reboot the EMG2881-T20A without turning the power off (Section 11.8 on
page 104).
• Use the Log screen to see the logs for the activity on the EMG2881-T20A (Section 11.9 on page 104).
• Use the ROMD screen to save and/or clean the configuration to/from the ROMD file which can store
customized default settings.
CHAPTER 11
Maintenance
11.3 General Screen
Use this screen to set the management session timeout period. Click Maintenance > General. The
following screen displays.
Figure 59 Maintenance > General
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The following table describes the labels in this screen.
Table 42 Maintenance > General
LABEL DESCRIPTION
System Name System Name is a unique name to identify the EMG2881-T20A in an Ethernet network.
Domain Name Enter the domain name you want to give to the EMG2881-T20A.
Administrator
Inactivity Timer
Apply Click Apply to save your changes back to the EMG2881-T20A.
Cancel Click Cancel to exit this screen without saving.
Type how many minutes a management session can be left idle before the session times out. The
default is 5 minutes. After it times out you have to log in with your password again. Very long idle
timeouts may have security risks. A value of "0" means a management session never times out,
no matter how long it has been left idle (not recommended).
11.4 Password Screen
It is strongly recommended that you change your EMG2881-T20A's password.
If you forget your EMG2881-T20A's password (or IP address), you will need to reset the device. See
Section 11.8 on page 104 for details.
Chapter 11 Maintenance
Click Maintenance > Password. The screen appears as shown.
Figure 60 Maintenance > Password
The following table describes the labels in this screen.
Table 43 Maintenance > Password
LABEL DESCRIPTION
User This field displays the name of the admin account.
Old Password Type the default password or the existing password you use to access the system in this
field.
New Password Type your new system password (up to 30 characters). Note that as you type a password,
the screen displays an asterisk (*) for each character you type.
Retype to Confirm Type the new password again in this field.
Apply Click Apply to save your changes back to the EMG2881-T20A.
Cancel Click Cancel to begin configuring this screen afresh.
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11.5 Time Screen
Use this screen to configure the EMG2881-T20A’s time based on your local time zone. To change your
EMG2881-T20A’s time and date, click Maintenance > Time. The screen appears as shown.
Figure 61 Maintenance > Time
Chapter 11 Maintenance
The following table describes the labels in this screen.
Table 44 Maintenance > Time
LABEL DESCRIPTION
Current Time and Date
Current Time This field displays the time of your EMG2881-T20A.
Each time you reload this page, the EMG2881-T20A synchronizes the time with the time server.
Current Date This field displays the date of your EMG2881-T20A.
Each time you reload this page, the EMG2881-T20A synchronizes the date with the time server.
Time and Date Setup
Manual Select this radio button to enter the time and date manually. If you configure a new time and
date, Time Zone and Daylight Saving at the same time, the new time and date you entered has
priority and the Time Zone and Daylight Saving settings do not affect it.
New Time
(hh:mm:ss)
New Date
(yyyy/mm/dd)
Get from Time
Server
User Defined
Time Server
Address
Time Zone Setup
Time Zone Choose the time zone of your location. This will set the time difference between your time zone
This field displays the last updated time from the time server or the last time configured manually.
When you select Manual, enter the new time in this field and then click Apply.
This field displays the last updated date from the time server or the last date configured
manually.
When you select Manual, enter the new date in this field and then click Apply.
Select this radio button to have the EMG2881-T20A get the time and date from the time server
you specified below.
Enter the IP address or URL (up to 20 extended ASCII characters in length) of your time server.
Check with your ISP/network administrator if you are unsure of this information.
and Greenwich Mean Time (GMT).
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Table 44 Maintenance > Time (continued)
LABEL DESCRIPTION
Daylight Savings Daylight saving is a period from late spring to early fall when many countries set their clocks
ahead of normal local time by one hour to give more daytime light in the evening.
Select this option if you use Daylight Saving Time.
Start Date Configure the day and time when Daylight Saving Time starts if you selected Daylight Savings.
The o’clock field uses the 24 hour format. Here are a couple of examples.
Daylight Saving Time starts in most parts of the United States on the first Sunday of April. Each
time zone in the United States starts using Daylight Saving Time at 2 A.M local time. So in the
United States you would select First, Sunday, April and type 2 in the o’clock field.
Daylight Saving Time starts in the European Union on the last Sunday of March. All of the time
zones in the European Union start using Daylight Saving Time at the same moment (1 A.m. GMT
or UTC). So in the European Union you would select Last, Sunday, March. The time you type in the
o’clock field depends on your time zone. In Germany for instance, you would type 2 because
Germany’s time zone is one hour ahead of GMT or UTC (GMT+1).
End Date Configure the day and time when Daylight Saving Time ends if you selected Daylight Savings.
The o’clock field uses the 24 hour format. Here are a couple of examples.
Daylight Saving Time ends in the United States on the last Sunday of October. Each time zone in
the United States stops using Daylight Saving Time at 2 A.M. local time. So in the United States
you would select Last, Sunday, October and type 2 in the o’clock field.
Daylight Saving Time ends in the European Union on the last Sunday of October. All of the time
zones in the European Union stop using Daylight Saving Time at the same moment (1 A.M. GMT
or UTC). So in the European Union you would select Last, Sunday, October. The time you type in
the o’clock field depends on your time zone. In Germany for instance, you would type 2
because Germany’s time zone is one hour ahead of GMT or UTC (GMT + 1).
Apply Click Apply to save your changes back to the EMG2881-T20A.
Cancel Click Cancel to exit this screen without saving.
11.6 Firmware Upgrade Screen
Find firmware at www.zyxel.com in a file that (usually) uses the system model name with a “*.bin”
extension, e.g., “EMG2881-T20A.bin”. The upload process uses HTTP (Hypertext Transfer Protocol) and
may take up to two minutes. After a successful upload, the system will reboot.
Click Maintenance > Firmware Upgrade. Follow the instructions in this screen to upload firmware to your
EMG2881-T20A.
Figure 62 Maintenance > Firmware Upgrade
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The following table describes the labels in this screen.
Table 45 Maintenance > Firmware Upgrade
LABEL DESCRIPTION
Firmware Upgrade
File Path Type in the location of the file you want to upload in this field or click Choose File to find it.
Choose File Click Choose File to find the .bin file you want to upload. Remember that you must decompress
compressed (.zip) files before you can upload them.
Upload Click Upload to begin the upload process. This process may take up to two minutes.
Do not turn off the EMG2881-T20A while firmware upload is in progress!
After you see the Firmware Upload In Process screen, wait two minutes before logging into the
EMG2881-T20A again.
The EMG2881-T20A automatically restarts in this time causing a temporary network disconnect. In some
operating systems, you may see the following icon on your desktop.
Figure 63 Network Temporarily Disconnected
After two minutes, log in again and check your new firmware version in the Status screen.
If the upload was not successful, an error message appears.
11.7 Configuration Backup/Restore Screen
Backup configuration allows you to back up (save) the EMG2881-T20A’s current configuration to a file
on your computer. Once your EMG2881-T20A is configured and functioning properly, it is highly
recommended that you back up your configuration file before making configuration changes. The
backup configuration file will be useful in case you need to return to your previous settings.
Restore configuration allows you to upload a new or previously saved configuration file from your
computer to your EMG2881-T20A.
Click Maintenance > Backup/Restore. Information related to factory defaults, backup configuration,
and restoring configuration appears as shown next.
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Figure 64 Maintenance > Backup/Restore
The following table describes the labels in this screen.
Table 46 Maintenance > Backup/Restore
LABEL DESCRIPTION
Backup Configuration
Backup Click Backup to save the EMG2881-T20A’s current configuration to your computer.
Restore Configuration
File Path Click Choose File to browse to the location of the configuration file in your computer.
Upload Click Upload to begin the upload process.
Note: Do not turn off the EMG2881-T20A while configuration file upload is in progress.
After you see a “configuration upload successful” screen, you must then wait one minute before
logging into the EMG2881-T20A again. The EMG2881-T20A automatically restarts in this time
causing a temporary network disconnect.
If you see an error screen, click Back to return to the Backup/Restore screen.
Reset Pressing the Reset button in this section clears all user-entered configuration information and
returns the EMG2881-T20A to its factory defaults.
You can also press the RESET button on the rear panel to reset the factory defaults of your
EMG2881-T20A. Refer to the chapter about introducing the Web Configurator for more
information on the RESET button.
Note: If you uploaded the default configuration file you may need to change the IP address
of your computer to be in the same subnet as that of the default EMG2881-T20A IP
address (192.168.1.1). See Appendix B on page 121 for details on how to set up your
computer’s IP address.
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11.8 Restart Screen
System restart allows you to reboot the EMG2881-T20A without turning the power off.
Click Maintenance > Restart to open the following screen.
Figure 65 Maintenance > Restart
Click Restart to have the EMG2881-T20A reboot. This does not affect the EMG2881-T20A's configuration.
11.9 Log Screen
Chapter 11 Maintenance
The Web Configurator allows you to look at all of the EMG2881-T20A’s logs in one location.
You can configure which logs to display in the Log screen. Select the logs you wish to display. Click
Apply to save your settings. Click Cancel to start the screen afresh.
Use this screen to see the logged messages for the EMG2881-T20A. The log wraps around and deletes
the old entries after it fills. Select what logs you want to see from the Display drop list. The log choices
depend on your settings above this screen. Click Refresh to renew the log screen. Click Clear Log to
delete all the logs.
Figure 66 Maintenance > Log
11.10 The ROMD Screen
Click Maintenance > ROMD to open the following screen.
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Figure 67 Maintenance > ROMD
Click Save to save the EMG2881-T20A’s current configuration to the ROM-D file. Click Clear to reset the
customized settings in the ROM-D file to factory defaults.
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12.1 Overview
This chapter offers some suggestions to solve problems you might encounter. The potential problems are
divided into the following categories.
• Power, Hardware Connections, and LEDs
• EMG2881-T20A Access and Login
• Internet Access
• Resetting the EMG2881-T20A to Its Factory Defaults
• Wireless Connections
CHAPTER 12
Troubleshooting
12.2 Power, Hardware Connections, and LEDs
The EMG2881-T20A does not turn on. None of the LEDs turn on.
1 Make sure you are using the power adaptor or cord included with the EMG2881-T20A.
2 Make sure the power adaptor or cord is connected to the EMG2881-T20A and plugged in to an
appropriate power source. Make sure the power source is turned on.
3 Disconnect and re-connect the power adaptor or cord to the EMG2881-T20A.
4 If the problem continues, contact the vendor.
One of the LEDs does not behave as expected.
1 Make sure you understand the normal behavior of the LED. See Section 1.5 on page 12.
2 Check the hardware connections. See the Quick Start Guide.
3 Inspect your cables for damage. Contact the vendor to replace any damaged cables.
4 Disconnect and re-connect the power adaptor to the EMG2881-T20A.
5 If the problem continues, contact the vendor.
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12.3 EMG2881-T20A Access and Login
I don’t know the IP address of my EMG2881-T20A.
1 The default IP address of the EMG2881-T20A in Router Mode is 192.168.1.1.
2 If you changed the IP address and have forgotten it, you might get the IP address of the EMG2881-T20A
in Router Mode by looking up the IP address of the default gateway for your computer. To do this in most
Windows computers, click Start > Run, enter cmd, and then enter ipconfig. The IP address of the Default
Gateway might be the IP address of the EMG2881-T20A (it depends on the network), so enter this IP
address in your Internet browser.
3 Reset your EMG2881-T20A to change all settings back to their default. This means your current settings
are lost. See Section 12.5 on page 109 in the Troubleshooting for information on resetting your EMG2881T20A.
I forgot the password.
1 The default password is the factory default (see the device label).
2 If this does not work, you have to reset the device to its factory defaults. See Section 12.5 on page 109.
I cannot see or access the Login screen in the Web Configurator.
1 Make sure you are using the correct IP address.
• The default IP address of the EMG2881-T20A in Router Mode is 192.168.1.1.
• If you changed the IP address (Section 8.4 on page 71), use the new IP address.
• If you changed the IP address and have forgotten it, see the troubleshooting suggestions for I don’t
know the IP address of my EMG2881-T20A.
2 Check the hardware connections, and make sure the LEDs are behaving as expected. See the Quick
Start Guide.
3 Make sure your Internet browser does not block pop-up windows and has JavaScript and Java
enabled. See Appendix A on page 112.
4 Make sure your computer is in the same subnet as the EMG2881-T20A. (If you know that there are routers
between your computer and the EMG2881-T20A, skip this step.)
• If there is a DHCP server on your network, make sure your computer is using a dynamic IP address.
See Section 8.4 on page 71.
• If there is no DHCP server on your network, make sure your computer’s IP address is in the same
subnet as the EMG2881-T20A. See Section 8.4 on page 71.
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5 Reset the device to its factory defaults, and try to access the EMG2881-T20A with the default IP address.
See Section 1.5.6 on page 14.
6 If the problem continues, contact the network administrator or vendor, or try one of the advanced
suggestions.
Advanced Suggestions
• Try to access the EMG2881-T20A using another service, such as Telnet. If you can access the
EMG2881-T20A, check the remote management settings and firewall rules to find out why the
EMG2881-T20A does not respond to HTTP.
• If your computer is connected to the WAN port or is connected wirelessly, use a computer that is
connected to a LAN/ETHERNET port.
I can see the Login screen, but I cannot log in to the EMG2881-T20A.
1 Make sure you have entered the password correctly. The default password is the factory default (see
the device label). This field is case-sensitive, so make sure [Caps Lock] is not on.
2 This can happen when you fail to log out properly from your last session. Try logging in again after 10
minutes.
3 Disconnect and re-connect the power adaptor or cord to the EMG2881-T20A.
4 If this does not work, you have to reset the device to its factory defaults. See Section 12.5 on page 109.
12.4 Internet Access
I cannot access the Internet.
1 Check the hardware connections, and make sure the LEDs are behaving as expected. See the Quick
Start Guide.
2 Make sure the WAN port is connected to a broadband modem or router with Internet access. Your
computer and the EMG2881-T20A should be in the same subnet.
3 Make sure you entered your ISP account information correctly in the wizard or the WAN screen. These
fields are case-sensitive, so make sure [Caps Lock] is not on.
4 If you are trying to access the Internet wirelessly, make sure the wireless settings in the wireless client are
the same as the settings in the AP.
5 Disconnect all the cables from your device, and follow the directions in the Quick Start Guide again.
6 If the problem continues, contact your ISP.
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