Asus Router RX3141 User Manual

							RX3141 User’s Manual Chapter 11. System Management 
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11.7.2 Restore System Configuration 
Follow the steps below to backup system configuration: 
1. Open the 
System Configuration Backup/Restore configuration page by double clicking the 
Management Î Backup/Restore menu. 
2.  Enter the path and filename of the system configuration file that you want to restore in the text 
field.  
 
 
Figure 11.19. System Configuration Restore Page 
Alternatively, you may click on the 
 button to search for the system configuration file 
on your computer. A window similar to the one shown in Figure 11.20 will pop up for you to select 
the configuration file to restore. Select the desired configuration file, and then click on the 
 button to continue. 
 
Figure 11.20. System Configuration Restore Page – Choose File Dialog  
						

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3. Click on  button to restore the system configuration.  
4.  A message will pop up, as illustrated in Figure 11.21, to let you know whether the system 
configuration is successfully restored. Note that you must reboot the RX3141 to make the new 
system configuration in effect. 
 
Figure 11.21. System Configuration Restore Status 
  
						

							RX3141 User’s Manual  Chapter 12. IP Addresses, Network Masks, and Subnets 
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12 IP Addresses, Network Masks, and Subnets 
12.1 IP Addresses 
 Note 
This section pertains only to IP addresses for IPv4 (version 4 of 
the Internet Protocol). IPv6 addresses are not covered. 
This section assumes basic knowledge of binary numbers, bits, 
and bytes. For details on this subject, see Appendix 12. 
IP addresses, the Internets version of telephone numbers, are used to identify individual nodes (computers or 
devices) on the Internet. Every IP address contains four numbers, each from 0 to 255 and separated by dots 
(periods), e.g. 20.56.0.211. These numbers are called, from left to right, field1, field2, field3, and field4. 
This style of writing IP addresses as decimal numbers separated by dots is called dotted decimal notation. The 
IP address 20.56.0.211 is read twenty dot fifty-six dot zero dot two-eleven. 
12.1.1 Structure of an IP address 
IP addresses have a hierarchical design similar to that of telephone numbers. For example, a 7-digit telephone 
number starts with a 3-digit prefix that identifies a group of thousands of telephone lines, and ends with four 
digits that identify one specific line in that group.  
Similarly, IP addresses contain two kinds of information. 
f Network ID 
Identifies a particular network within the Internet or Intranet 
f Host ID 
Identifies a particular computer or device on the network 
The first part of every IP address contains the network ID, and the rest of the address contains the host ID. 
The length of the network ID depends on the networks class (see following section). Table 12.1 shows the 
structure of an IP address. 
Table 12.1. IP Address Structure 
 Field1 Field2 Field3 Field4 
Class A  Network ID  Host ID 
Class B  Network ID  Host ID 
Class C  Network ID  Host ID 
Here are some examples of valid IP addresses: 
Class A: 10.30.6.125 (network = 10, host = 30.6.125) 
Class B: 129.88.16.49 (network = 129.88, host = 16.49) 
Class C: 192.60.201.11 (network = 192.60.201, host = 11)  
						

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12.2 Network classes 
The three commonly used network classes are A, B, and C. (There is also a class D but it has a special use 
beyond the scope of this discussion.) These classes have different uses and characteristics.  
Class A networks are the Internets largest networks, each with room for over 16 million hosts. Up to 126 of 
these huge networks can exist, for a total of over 2 billion hosts. Because of their huge size, these networks 
are used for WANs and by organizations at the infrastructure level of the Internet, such as your ISP. 
Class B networks are smaller but still quite large, each able to hold over 65,000 hosts. There can be up to 
16,384 class B networks in existence. A class B network might be appropriate for a large organization such as 
a business or government agency. 
Class C networks are the smallest, only able to hold 254 hosts at most, but the total possible number of class 
C networks exceeds 2 million (2,097,152 to be exact). LANs connected to the Internet are usually class C 
networks. 
Some important notes regarding IP addresses: 
f  The class can be determined easily from field1: 
 field1 = 1-126:  Class A 
 field1 = 128-191:  Class B 
 field1 = 192-223:  Class C 
(field1 values not shown are reserved for special uses) 
f  A host ID can have any value except all fields set to 0 or all fields set to 255, as those values are 
reserved for special uses.  
						

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12.3 Subnet masks 
 
Definition 
mask 
A mask looks like a regular IP address, but contains a pattern of 
bits that tells what parts of an IP address are the network ID and 
what parts are the host ID: bits set to 1 mean this bit is part of the 
network ID and bits set to 0 mean this bit is part of the host ID. 
Subnet masks are used to define subnets (what you get after dividing a network into smaller pieces). A 
subnets network ID is created by borrowing one or more bits from the host ID portion of the address. The 
subnet mask identifies these host ID bits. 
For example, consider a class C network 192.168.1. To split this into two subnets, you would use the subnet 
mask: 
255.255.255.128 
Its easier to see whats happening if we write this in binary:  
11111111. 11111111. 11111111.10000000 
As with any class C address, all of the bits in field1 through field 3 are part of the network ID, but note how the 
mask specifies that the first bit in field 4 is also included. Since this extra bit has only two values (0 and 1), this 
means there are two subnets. Each subnet uses the remaining 7 bits in field4 for its host IDs, which range from 
0 to 127 (instead of the usual 0 to 255 for a class C address). 
Similarly, to split a class C network into four subnets, the mask is: 
255.255.255.192    or    11111111. 11111111. 11111111.11000000 
The two extra bits in field4 can have four values (00, 01, 10, 11), so there are four subnets. Each subnet uses 
the remaining six bits in field4 for its host IDs, ranging from 0 to 63. 
 Note 
Sometimes a subnet mask does not specify any additional 
network ID bits, and thus no subnets. Such a mask is called a 
default subnet mask. These masks are: 
Class A:  255.0.0.0 
Class B:  255.255.0.0 
Class C:  255.255.255.0 
These are called default because they are used when a network is 
initially configured, at which time it has no subnets. 
  
						

							RX3141 User’s Manual Appendix   
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13 Troubleshooting 
This appendix suggests solutions for problems you may encounter in installing or using the RX3141, and 
provides instructions for using several IP utilities to diagnose problems.  
Contact Customer Support if these suggestions do not resolve the problem. 
 
Problem Troubleshooting Suggestion 
Power LED does not 
illuminate after 
product is turned on. Verify that you are using the AC adapter provided with the 
device and that it is securely connected to the RX3141 and a 
wall socket/power strip. 
LINK WAN LED 
does not illuminate 
after Ethernet cable 
is attached. Verify that an Ethernet cable like the one provided is securely 
connected to the Ethernet port of your ADSL or cable modem 
and the WAN port of the RX3141. Make sure that your ADSL or 
cable modem is powered on. Wait 30 seconds to allow the 
RX3141 to negotiate a connection with your broadband modem. 
LINK LAN LED does 
not illuminate after 
Ethernet cable is 
attached. Verify that the Ethernet cable is securely connected to your LAN 
hub or PC and to the RX3141. Make sure the PC and/or hub is 
turned on. 
Verify that your cable is sufficient for your network requirements. 
A 100 Mbit/sec network (100BaseTx) should use cables labeled 
Cat 5. 10Mbit/sec cables may tolerate lower quality cables. 
Internet Access 
PC cannot access 
Internet Use the ping utility, discussed in the following section, to check 
whether your PC can communicate with the RX3141’s LAN IP 
address (by default 192.168.1.1). If it cannot, check the Ethernet 
cabling.  
If you statically assigned a private IP address to the computer, 
(not a registered public address), verify the following: 
•  Check that the gateway IP address on the computer is 
your public IP address (see the Quick Start Guide 
chapter, Part 2 for instructions on viewing the IP 
information.) If it is not, correct the address or configure 
the PC to receive IP information automatically. 
•  Verify with your ISP that the DNS server specified for the 
PC is valid. Correct the address or configure the PC to 
receive this information automatically. 
•  Verify that a Network Address Translation rule has been 
defined on the RX3141 to translate the private address 
to your public IP address. The assigned IP address must 
be within the range specified in the NAT rules. Or, 
configure the PC to accept an address assigned by 
another device (see section 3.2 Part 2 — Configuring 
Your Computers”). The default configuration includes a 
NAT rule for all dynamically assigned addresses within a 
predefined pool   
						

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Problem Troubleshooting Suggestion 
PCs cannot display 
web pages on the 
Internet. Verify that the DNS server specified on the PCs is correct for 
your ISP, as discussed in the item above. You can use the ping 
utility, discussed in the following section, to test connectivity with 
your ISP’s DNS server. 
Configuration Manager Program 
You forgot/lost your 
Configuration 
Manager user ID or 
password. If you have not changed the password from the default, try using 
“admin” as the user ID and “admin” for the password. Otherwise, 
you can reset the device to the default configuration by following 
the instructions provided in section 11.4 “Reset to Factory 
Default Settings”. 
WARNING: Resetting the device removes 
any custom settings and returns all settings to their default 
values. 
Cannot access the 
Configuration 
Manager program 
from your browser. Use the ping utility, discussed in the following section, to check 
whether your PC can communicate with the RX3141’s LAN IP 
address (by default 192.168.1.1). If it cannot, check the Ethernet 
cabling. 
Verify that you are using Internet Explorer 6.0 or newer. Support 
for Javascript® must be enabled in your browser. Support for 
Java® may also be required. 
Verify that the PC’s IP address is defined as being on the same 
subnet as the IP address assigned to the LAN port on the 
RX3141. 
Changes to 
Configuration 
Manager are not 
being retained. Be sure to click on  button to save any changes. 
13.1  Diagnosing Problem using IP Utilities 
13.1.1 ping 
Ping is a command you can use to check whether your PC can recognize other computers on your network 
and the Internet. A ping command sends a message to the computer you specify. If the computer receives the 
message, it sends messages in reply. To use it, you must know the IP address of the computer with which you 
are trying to communicate.  
On Windows-based computers, you can execute a ping command from the Start menu. Click the Start button, 
and then click Run. In the Open text box, type a statement such as the following: 
ping 192.168.1.1 
Click . You can substitute any private IP address on your LAN or a public IP address for an Internet 
site, if known.  
If the target computer receives the message, a Command Prompt window displays like that shown in Figure 
13.1.  
						

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Figure 13.1. Using the ping Utility 
If the target computer cannot be located, you will receive the message “Request timed out.” 
Using the ping command, you can test whether the path to the RX3141 is working (using the preconfigured 
default LAN IP address 192.168.1.1) or another address you assigned. 
You can also test whether access to the Internet is working by typing an external address, such as that for 
www.yahoo.com
 (216.115.108.243). If you do not know the IP address of a particular Internet location, you can 
use the nslookup command, as explained in the following section. 
From most other IP-enabled operating systems, you can execute the same command at a command prompt 
or through a system administration utility. 
13.1.2 nslookup 
You can use the nslookup command to determine the IP address associated with an Internet site name. You 
specify the common name, and the nslookup command looks up the name on your DNS server (usually 
located with your ISP). If that name is not an entry in your ISP’s DNS table, the request is then referred to 
another higher-level server, and so on, until the entry is found. The server then returns the associated IP 
address. 
On Windows-based computers, you can execute the nslookup command from the Start menu. Click the Start 
button, and then click Run. In the Open text box, type the following: 
nslookup 
Click . A Command Prompt window displays with a bracket prompt (>). At the prompt, type the 
name of the Internet address you are interested in, such as www.absnews.com
. 
The window will display the associate IP address, if known, as shown in Figure 13.2.  
						

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Figure 13.2. Using the nslookup Utility 
There may be several addresses associated with an Internet name. This is common for web sites that receive 
heavy traffic; they use multiple, redundant servers to carry the same information. 
To exit from the nslookup utility, type 
exit and press  at the command prompt.