User manual NETGEAR WGR826V

[. . . ] Reference Manual for the 54 Mbps Wireless Router with Phone Adapter WGR826V NETGEAR, Inc. 4500 Great America Parkway Santa Clara, CA 95054 USA 202-10051-01 March 2005 202-10051-01, March 2005 © 2005 by NETGEAR, Inc. Microsoft, Windows, and Windows NT are registered trademarks of Microsoft Corporation. Other brand and product names are registered trademarks or trademarks of their respective holders. [. . . ] The dividing point may vary depending on the address range and the application. B-2 Network, Routing, and Firewall Basics 202-10051-01, March 2005 Reference Manual for the 54 Mbps Wireless Router with Phone Adapter WGR826V There are five standard classes of IP addresses. These address classes have different ways of determining the network and host sections of the address, allowing for different numbers of hosts on a network. Each address type begins with a unique bit pattern, which is used by the TCP/IP software to identify the address class. After the address class has been determined, the software can correctly identify the host section of the address. The follow figure shows the three main address classes, including network and host sections of the address for each address type. Class A Network Class B Node Network Node Class C Network Node 7261 Figure B-1: Three Main Address Classes The five address classes are: · Class A Class A addresses can have up to 16, 777, 214 hosts on a single network. Class A addresses are in this range: 1. x. x. x to 126. x. x. x. · Class B Class B addresses can have up to 65, 354 hosts on a network. A Class B address uses a 16-bit network number and a 16-bit node number. Class B addresses are in this range: 128. 1. x. x to 191. 254. x. x. · Class C Class C addresses can have 254 hosts on a network. Class C addresses use 24 bits for the network address and eight bits for the node. They are in this range: 192. 0. 1. x to 223. 255. 254. x. Network, Routing, and Firewall Basics 202-10051-01, March 2005 B-3 Reference Manual for the 54 Mbps Wireless Router with Phone Adapter WGR826V · Class D Class D addresses are used for multicasts (messages sent to many hosts). Class D addresses are in this range: 224. 0. 0. 0 to 239. 255. 255. 255. · Class E Class E addresses are for experimental use. This addressing structure allows IP addresses to uniquely identify each physical network and each node on each physical network. For each unique value of the network portion of the address, the base address of the range (host address of all zeros) is known as the network address and is not usually assigned to a host. Also, the top address of the range (host address of all ones) is not assigned, but is used as the broadcast address for simultaneously sending a packet to all hosts with the same network address. Netmask In each of the address classes previously described, the size of the two parts (network address and host address) is implied by the class. This partitioning scheme can also be expressed by a netmask associated with the IP address. A netmask is a 32-bit quantity that, when logically combined (using an AND operator) with an IP address, yields the network address. For instance, the netmasks for Class A, B, and C addresses are 255. 0. 0. 0, 255. 255. 0. 0, and 255. 255. 255. 0, respectively. For example, the address 192. 168. 170. 237 is a Class C IP address whose network portion is the upper 24 bits. When combined (using an AND operator) with the Class C netmask, as shown here, only the network portion of the address remains: 11000000 10101000 10101010 11101101 (192. 168. 170. 237) combined with: 11111111 11111111 11111111 00000000 (255. 255. 255. 0) Equals: 11000000 10101000 10101010 00000000 (192. 168. 170. 0) As a shorter alternative to dotted-decimal notation, the netmask may also be expressed in terms of the number of ones from the left. This number is appended to the IP address, following a backward slash (/), as "/n. " In the example, the address could be written as 192. 168. 170. 237/24, indicating that the netmask is 24 ones followed by 8 zeros. B-4 Network, Routing, and Firewall Basics 202-10051-01, March 2005 Reference Manual for the 54 Mbps Wireless Router with Phone Adapter WGR826V Subnet Addressing By looking at the addressing structures, you can see that even with a Class C address, there are a large number of hosts per network. Such a structure is an inefficient use of addresses if each end of a routed link requires a different network number. It is unlikely that the smaller office LANs would have that many devices. You can resolve this problem by using a technique known as subnet addressing. [. . . ] To use WPA-PSK, a person sets a static key or "passphrase" as with WEP. But, using TKIP, WPA-PSK automatically changes the keys at a preset time interval, making it much more difficult for hackers to find and exploit them. The Wi-Fi Alliance will call this, 'WPA-Personal. ' Wi-Fi Protected Access and IEEE 802. 11i Comparison Wi-Fi Protected Access will be forward-compatible with the IEEE 802. 11i security specification currently under development by the IEEE. Wi-Fi Protected Access is a subset of the current 802. 11i draft, taking certain pieces of the 802. 11i draft that are ready to bring to market today, such as its implementation of 802. 1x and TKIP. [. . . ]