Netgear Router WGR614v7 User Manual

							54 Mbps Wireless Router WGR614v7 Reference Manual
Network, Routing, Firewall, and Basics B-9
April 2006
If a device sends data to another station on the network and the destination MAC address is not yet 
recorded, ARP is used. An ARP request is broadcast onto the network. All stations on the network 
receive and read the request. The destination IP address for the chosen station is included as part of 
the message so that only the station with this IP address responds to the ARP request. All other 
stations discard the request. 
Related Documents
The station with the correct IP address responds with its own MAC address directly to the sending 
device. The receiving station provides the transmitting station with the required destination MAC 
address. The IP address data and MAC address data for each station are held in an ARP table. The 
next time data is sent, the address can be obtained from the address information in the table.
For more information about address assignment, refer to the IETF documents RFC 1597, Address 
Allocation for Private Internets, and RFC 1466, Guidelines for Management of IP Address Space.
For more information about IP address translation, refer to RFC 1631, The IP Network Address 
Translator (NAT).
Domain Name Server
Many of the resources on the Internet can be addressed by simple descriptive names such as 
www.NETGEAR.com. This addressing is very helpful at the application level, but the descriptive 
name must be translated to an IP address in order for a user to actually contact the resource. Just as 
a telephone directory maps names to phone numbers, or as an ARP table maps IP addresses to 
MAC addresses, a domain name system (DNS) server maps descriptive names of network 
resources to IP addresses.
When a computer accesses a resource by its descriptive name, it first contacts a DNS server to 
obtain the IP address of the resource. The computer sends the desired message using the IP 
address. Many large organizations, such as ISPs, maintain their own DNS servers and allow their 
customers to use the servers to look up addresses. 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
B-10 Network, Routing, Firewall, and Basics
April 2006
IP Configuration by DHCP
When an IP-based local area network is installed, each computer must be configured with an 
IP address. If the computers need to access the Internet, they should also be configured with a 
gateway address and one or more DNS server addresses. As an alternative to manual 
configuration, there is a method by which each computer on the network can automatically obtain 
this configuration information. A device on the network may act as a Dynamic Host Configuration 
Protocol (DHCP) server. The DHCP server stores a list or pool of IP addresses, along with other 
information (such as gateway and DNS addresses) that it may assign to the other devices on the 
network. The wireless router has the capacity to act as a DHCP server.
The wireless router also functions as a DHCP client when connecting to the ISP. The firewall can 
automatically obtain an IP address, subnet mask, DNS server addresses, and a gateway address if 
the ISP provides this information by DHCP.
Internet Security and Firewalls
When your LAN connects to the Internet through a router, an opportunity is created for outsiders 
to access or disrupt your network. A NAT router provides some protection because by the very 
nature of the process, the network behind the router is shielded from access by outsiders on the 
Internet. However, there are methods by which a determined hacker can possibly obtain 
information about your network or at the least can disrupt your Internet access. A greater degree of 
protection is provided by a firewall router.
What is a Firewall?
A firewall is a device that protects one network from another, while allowing communication 
between the two. A firewall incorporates the functions of the NAT router, while adding features for 
dealing with a hacker intrusion or attack. Several known types of intrusion or attack can be 
recognized when they occur. When an incident is detected, the firewall can log details of the 
attempt, and can optionally send E-mail to an administrator notifying them of the incident. Using 
information from the log, the administrator can take action with the ISP of the hacker. In some 
types of intrusions, the firewall can fend off the hacker by discarding all further packets from the 
hacker’s IP address for a period of time. 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
Network, Routing, Firewall, and Basics B-11
April 2006
Stateful Packet Inspection
Unlike simple Internet sharing routers, a firewall uses a process called stateful packet inspection to 
ensure secure firewall filtering to protect your network from attacks and intrusions. Since 
user-level applications such as FTP and Web browsers can create complex patterns of network 
traffic, it is necessary for the firewall to analyze groups of network connection states. Using 
Stateful Packet Inspection, an incoming packet is intercepted at the network layer and then 
analyzed for state-related information associated with all network connections. A central cache 
within the firewall keeps track of the state information associated with all network connections. 
All traffic passing through the firewall is analyzed against the state of these connections in order to 
determine whether or not it will be allowed to pass through or rejected.
Denial of Service Attack
A hacker may be able to prevent your network from operating or communicating by launching a 
Denial of Service (DoS) attack. The method used for such an attack can be as simple as merely 
flooding your site with more requests than it can handle. A more sophisticated attack may attempt 
to exploit some weakness in the operating system used by your router or gateway. Some operating 
systems can be disrupted by simply sending a packet with incorrect length information.
Ethernet Cabling
Although Ethernet networks originally used thick or thin coaxial cable, most installations currently 
use unshielded twisted pair (UTP) cabling. The UTP cable contains eight conductors, arranged in 
four twisted pairs, and terminated with an RJ45 type connector. A normal straight-through UTP 
Ethernet cable follows the EIA568B standard wiring as described below in Ta b l e  B - 1.
Table B-1. UTP Ethernet cable wiring, straight-through  
Pin Wire color Signal
1 Orange/White Transmit (Tx) +
2 Orange Transmit (Tx) -
3 Green/White Receive (Rx) +
4Blue
5 Blue/White
6 Green Receive (Rx) - 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
B-12 Network, Routing, Firewall, and Basics
April 2006
Category 5 Cable Quality
Category 5 distributed cable that meets ANSI/EIA/TIA-568-A building wiring standards can be a 
maximum of 328 feet (ft.) or 100 meters (m) in length, divided as follows:
20 ft. (6 m) between the hub and the patch panel (if used)
295 ft. (90 m) from the wiring closet to the wall outlet
10 ft. (3 m) from the wall outlet to the desktop device
The patch panel and other connecting hardware must meet the requirements for 100 Mbps 
operation (Category 5). Only 0.5 inch (1.5 cm) of untwist in the wire pair is allowed at any 
termination point.
A twisted pair Ethernet network operating at 10 Mbits/second (10BASE-T) will often tolerate low 
quality cables, but at 100 Mbits/second (10BASE-Tx) the cable must be rated as Category 5, or 
Cat 5, by the Electronic Industry Association (EIA). This rating will be printed on the cable jacket. 
A Category 5 cable will meet specified requirements regarding loss and crosstalk. In addition, 
there are restrictions on maximum cable length for both 10 and 100 Mbits/second networks.
Inside Twisted Pair Cables
For two devices to communicate, the transmitter of each device must be connected to the receiver 
of the other device. The crossover function is usually implemented internally as part of the 
circuitry in the device. Computers and workstation adapter cards are usually media-dependent 
interface ports, called MDI or uplink ports. Most repeaters and switch ports are configured as 
media-dependent interfaces with built-in crossover ports, called MDI-X or normal ports. Auto 
Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes 
the right connection.
Figure B-4 illustrates straight-through twisted pair cable.
7 Brown/White
8Brown
Table B-1. UTP Ethernet cable wiring, straight-through  (continued)
Pin Wire color Signal 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
Network, Routing, Firewall, and Basics B-13
April 2006 Figure B-4:   Straight-Through Twisted-Pair Cable
Figure B-5 illustrates crossover twisted pair cable.
Figure B-5:   Crossover Twisted-Pair Cable 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
B-14 Network, Routing, Firewall, and Basics
April 2006 Figure B-6:   Category 5 UTP Cable with Male RJ-45 Plug at Each End
Note: Flat “silver satin” telephone cable may have the same RJ-45 plug. However, using telephone 
cable results in excessive collisions, causing the attached port to be partitioned or disconnected 
from the network.
Uplink Switches, Crossover Cables, and MDI/MDIX Switching
In the wiring table above, the concept of transmit and receive are from the perspective of the 
computer, which is wired as Media Dependant Interface (MDI). In this wiring, the computer 
transmits on pins 1 and 2. At the hub, the perspective is reversed, and the hub receives on pins 1 
and 2. This wiring is referred to as Media Dependant Interface - Crossover (MDI-X). 
When connecting a computer to a computer, or a hub port to another hub port, the transmit pair 
must be exchanged with the receive pair. This exchange is done by one of two mechanisms. Most 
hubs provide an Uplink switch which will exchange the pairs on one port, allowing that port to be 
connected to another hub using a normal Ethernet cable. The second method is to use a crossover 
cable, which is a special cable in which the transmit and receive pairs are exchanged at one of the 
two cable connectors. Crossover cables are often unmarked as such, and must be identified by 
comparing the two connectors. Since the cable connectors are clear plastic, it is easy to place them 
side by side and view the order of the wire colors on each. On a straight-through cable, the color 
order will be the same on both connectors. On a crossover cable, the orange and green pairs will be 
exchanged from one connector to the other. 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
Network, Routing, Firewall, and Basics B-15
April 2006
The wireless router incorporates Auto UplinkTM technology (also called MDI/MDIX). Each 
LOCAL Ethernet port will automatically sense whether the Ethernet cable plugged into the port 
should have a normal connection (e.g. connecting to a computer) or an uplink connection (e.g. 
connecting to a router, switch, or hub). That port will then configure itself to the correct 
configuration. This feature also eliminates the need to worry about crossover cables, as Auto 
Uplink
TM will accommodate either type of cable to make the right connection. 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
B-16 Network, Routing, Firewall, and Basics
April 2006 
						

							Preparing Your Network C-1
April 2006
Appendix C
Preparing Your Network
This appendix describes how to prepare your network to connect to the Internet through the 54 
Mbps Wireless Router WGR614v7 and how to verify the readiness of broadband Internet service 
from an Internet service provider (ISP).
What You Need To Use a Router with a Broadband Modem
You need to prepare these three things before you begin:
Cabling and Computer Hardware
To use the wireless router on your network, each computer must have an 802.11g or 802.11b 
wireless adapter or an installed Ethernet Network Interface Card (NIC) and an Ethernet cable. If 
the computer will connect to your network using an Ethernet NIC at 100 Mbps, you must use a 
Category 5 (Cat 5) cable such as the one provided with your router. For an explanation of Ethernet 
cabling, see “Ethernet Cabling“ on page B-11. The cable or DSL broadband modem must provide 
a standard 10 Mbps (10BASE-T) or 100 Mbps (100BASE-Tx) Ethernet interface. 
Computer Network Configuration Requirements
The WGR614v7 includes a built-in Web Configuration Manager. To access the configuration 
menus on the WGR614v7, your must use a Java-enabled Web browser program which supports 
HTTP uploads such as Microsoft Internet Explorer or Netscape Navigator. Use Internet Explorer 
5.0 and above and Netscape Navigator 4.7 and above. 
Note: If an ISP technician configured your computer during the installation of a 
broadband modem, or if you configured it using instructions provided by your ISP, you 
may need to copy the current configuration information for use in the configuration of 
your router. Write down this information before reconfiguring your computers. Refer to 
“Obtaining ISP Configuration Information for Windows Computers” on page C-21 or 
“Obtaining ISP Configuration Information for Macintosh Computers” on page C-22 for 
further information. 
						

							54 Mbps Wireless Router WGR614v7 Reference Manual
C-2 Preparing Your Network
April 2006
For the initial setup of your router, you will need to connect a computer to the router. This 
computer has to be set to automatically get its TCP/IP configuration from the router via DHCP.
Note: For help with DHCP configuration, please use the Windows TCP/IP Configuration 
Tutorials on the Resource CD, or in this appendix.
Internet Configuration Requirements
Depending on how your Internet service set up your account, you may need one or more of these 
configuration parameters to connect your router to the Internet: 
• Host and Domain Names
• ISP Login Name and Password
• ISP Domain Name Server (DNS) Addresses
• Fixed IP Address which is also known as Static IP Address
Where Do I Get the Internet Configuration Parameters?
There are several ways you can gather the required Internet connection information.
• Your Internet service provides all the information needed to connect to the Internet. If you 
cannot locate this information, you can ask your Internet service to provide it or you can try 
one of the options below.
• If you have a computer already connected using the Internet, you can gather the configuration 
information from that computer.
— For Windows 95/98/ME, open the Network control panel, select the TCP/IP entry for the 
Ethernet adapter, and click Properties. Record all the settings for each tab page.
— For Windows 2000/XP, open the Local Area Network Connection, select the TCP/IP entry 
for the Ethernet adapter, and click Properties. Record all the settings for each tab page.
— For Macintosh computers, record the settings in the TCP/IP or Network control panel. 
• You may also refer to the Resource CD for the NETGEAR Router ISP Guide which provides 
Internet connection information for many ISPs.
Once you locate your Internet configuration parameters, you may want to record them on the page 
below.