IP Address Classes

In a networking infrastructure, the deployment of the correct and well managed IP addresses is very essential. With the unique IP address configured on each hosts, the hosts can communicate on a private TCP/IP network or on the public Internet. Being familiar with the IP Address Classes will help you manage the deployment of the IP address in the network.

Speaking about the IP Address Classes, IP addresses can be grouped into two categories: public IP addresses and private IP addresses. Public addresses are the globally unique addresses that are connected to the Internet. Private addresses are confined to specific ranges that can be used by any private network but that cannot be seen on the public Internet.

The IP Address Classes

Determining the IP Address Classes can start by identifying the value of the first octet, designates which of its 32 bits represent the default network ID, how many hosts that network can support. There are five IP address classes defined by the internet community but only Class A, B, and C addresses are used for assignment to TCP/IP nodes.

The following table uses x, w, y, z to designate the four octet values in any given IP address to show the following:

• The IP address classes can be identified by the value of the first octet (w) of any given IP address.
• The octets in an IP address are divided into network ID and host ID
• The number of possible networks and hosts per network available for each class

Network ID and Host ID

In an internetworking communication the routers that direct packets of data between TCP/IP networks do not usually need to know the exact host for which an IP packet is destined. The routers just need to read the destination network address of which the particular destination host is a member.

The routers that direct packets of data between TCP/IP networks do not usually need to know the exact host for which an IP packet is destined. Instead, routers need to read from an IP packet only the destination network address of which the particular destination host is a member. By examining the information stored in the routing tables, the routers then decide where to move the packets toward the network. Only after the packet is delivered to the destination’s network segment is the precise location of the destination host determined.

IP Address Classes

To assist in this routing process, an IP address is divided into two components:

• The first part of an IP address, the network ID, identifies a particular network within a larger TCP/IP internetwork (such as the Internet).
• The last part of an IP address, the host ID, identifies a TCP/IP host (a workstation, server, router, or other TCP/IP device) specific to the network defined by the network ID.

Using Private IP Addresses

The IANA has reserved a certain number of IP addresses that are never used on the global Internet. For your private network, you can use the private IP addresses defined by the IANA. This private address is not seen on the public network.

For example, a user connecting computers in a home TCP/IP network does not need to assign a public IP address to each host. The user instead can take advantage of the address ranges shown in the following private IP addresses table.

Hosts addressed with a private IP address can connect to the Internet through the use of a proxy server or a computer running Windows Server 2003 configured as a Network Address Translation (NAT) server. Windows Server 2003 also includes the Internet Connection Sharing (ICS) feature that provides simplified NAT services to clients in a private network

Related posts:

• IP address design – discussing the IP address design in a multi-network environment
• Calculate subnet mask – understanding the network sub-netting
• Change the IP address – guideline in changing the IP address
• Find the IP address – locating the IP address assigned to the hosts