Netgear WGR614v3 WGR614v3 Reference Manual - Page 90

Netmask, associated with the IP address. A netmask is a 32-bit quantity

Page 90 highlights

Reference Manual for Cable/DSL Wireless Router WGR614 • 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. • 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) B-4 Network, Routing, Firewall, and Basics

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Reference Manual for Cable/DSL Wireless Router WGR614
B-4
Network, Routing, Firewall, and Basics
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.
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)