Allow hosts to participate on IP based networks

  Allow hosts to participate on IP based networks 

IP Address

 

·         allow hosts to participate on IP based networks and it is a 32-bit binary number represented as four octets (four 8-bit numbers). Each octet is separated by a period.

 

IP Address

 

·         can be represented in one of two ways: Decimal or Binary

 

Decimal

 

·         (for example 131.107.2.200). In decimal notation, each octet must be between 0 and 255

 

Binary

 

·         (for example 10000011.01101011.00000010.11001000). In binary notation, each octet is an 8-character number

 

Converting

 

·         To convert from binary to decimal, memorize the decimal equivalent to the binary numbers:
10000000=128
01000000=64
00100000=32
00010000=16
00001000=08
00000100=04
00000010=02
00000001-01
For each bit position with a 1 value, add the decimal values for that bit together. For example, the decimal equivalent of 10010101 is:
128 + 16 + 4 + 1 = 149

 

 

The IP address

 

·         includes both the network and the host address

 

The subnet mask

 

·         is a 32-bit number that is associated with each IP address that identifies the network portion of the address. In binary form, the subnet mask is always a series of 1's followed by a series of 0's (1's and 0's are never mixed in sequence in the mask). A simple mask might be 255.255.255.0.

 

IP addresses

 

·         have a default class. The address class identifies the range of IP addresses and a default subnet mask used for the range

 

Class A

 

·         Address Range 1.0.0.0 to 126.255.255.255, First Octet Range 1-126 (00000001-01111110 binary), Default Subnet Mask 255.0.0.0 When using the default subnet mask for an IP address, you have the following number of subnet addresses and hosts per subnet:

There are only 126 Class A network IDs (most of these addresses are already assigned).
Each class A address gives you 16,777,214 hosts per network.

 

 

Class B

 

·         Address Range 128.0.0.0 to 191.255.255.255, First Octet Range 128-191 (10000000--10111111 binary), Default Subnet Mask 255.255.0.0
There are 16,384 Class B network IDs. Each class B address gives you 65,534 hosts per network.

 

Class C

 

·         Address Range 192.0.0.0 to 223.255.255.255, First Octet Range 192-223
(11000000--11011111 binary)Default Subnet Mask 255.255.255.0
There are 2,097,152 Class C network IDs. Each class C address gives you 254 hosts per network.

 

Class D

 

·         Address Range 224.0.0.0 to 239.255.255.255, First Octet Range 224-239
(11100000--11101111 binary), Default Subnet Mask n/a
Class D addresses are used for multicast groups rather than network and host IDs.

 

Class E

 

·         Address Range 240.0.0.0 to 255.255.255.255, First Octet Range 240-255
(11110000--11111111 binary)Default Subnet Mask n/a
Class E addresses are reserved for experimental use.

 

Network

 

·         The first address in an address range is used to identify the network itself. For the network address, the host portion of the address contains all 0's. For example:

Class A network address: 115.0.0.0
Class B network address: 154.90.0.0
Class C network address: 221.65.244.0

 

Broadcast

 

·         The last address in the range is used as the broadcast address and is used to send messages to all hosts on the network. In binary form, the broadcast address has all 1's in the host portion of the address. For example, assuming the default subnet masks are used:

115.255.255.255 is the broadcast address for network 115.0.0.0
154.90.255.255 is the broadcast address for network 154.90.0.0
221.65.244.255 is the broadcast address for network 221.65.244.0

The broadcast address might also be designated by setting each of the network address bits to 0. For example, 0.0.255.255 is the broadcast address of a Class B address. This designation means "the broadcast address for this network."

 

Host Addresses

 

·         When you are assigning IP addresses to hosts, be aware of the following:

Each host must have a unique IP address.
Each host on the same network must have an IP address with a common network portion of the address. This means that you must use the same subnet mask when configuring addresses for hosts on the same network.

The range of IP addresses available to be assigned to network hosts is identified by the subnet mask and/or the address class. When assigning IP addresses to hosts, be aware that you cannot use the first or last addresses in the range (these are reserved for the network and broadcast addresses respectively). For example:

For the class A network address 115.0.0.0, the host range is 115.0.0.1 to 115.255.255.254.
For the class B network address 154.90.0.0, the host range is 154.90.0.1 to 154.90.255.254.
For the class C network address 221.65.244.0, the host range is 221.65.244.1 to 221.65.244.254.

A special way to identify a host on a network is by setting the network portion of the address to all 0's. For example, the address 0.0.64.128 means "host 64.128 on this network."

 

Local Host

 

·         Addresses in the 127.0.0.0 range are reserved to refer to the local host (in other words "this" host or the host you're currently working at). The most commonly-used address is 127.0.0.1 which is the loopback address.