Learn Windows XP Professional in 15 Minutes a Week: TCP/IP Addressing in Windows XP Professional

By ServerWatch Staff (Send Email)
Posted Aug 5, 2002


by Jason Zandri
www.2000trainers.com

Welcome to this week's installment of Learn Windows XP Professional in 15 minutes a week, the 13th in this series. This article will continue covering the TCP/IP Protocol within Windows XP Professional with a specific focus on administration and management of the network protocol under Windows XP Professional.


Jason Zandri's latest article in the Learning Windows XP Professional in 15 Minutes a Week series covers the TCP/IP Protocol with a specific focus on administration and management of the network protocol under Windows XP Professional.

Internet Protocol Addressing Overview

The Transmission Control Protocol/Internet Protocol is a network communication protocol. It can be used as a communications protocol on private networks and is the default protocol in use on the internet. When you set up any system to have direct access to the Internet, whether it is via dial-up or one of the high speed technologies in use today, your system will need to utilize the TCP/IP protocol (whether it is a Windows-based system or not).

Also, if the given system needs to communicate with other TCP/IP systems on the local LAN or WAN, it will need to utilize the TCP/IP protocol as well.

[NOTES FROM THE FIELD] - This is just a basic overview of TCP/IP, and I didn't want to get too involved with it within this article. There is bountiful information on TCP/IP all over the internet and before pouring through the RFCs I would first suggest you try these two resources -- TCP/IP Frequently Asked Questions or TCP/IP Protocol Suite - Questions & Answers.

I have gone into a more detailed overview of the TCP/IP Protocol in last week's article, which covered the four-layer conceptual model of TCP/IP and how the model stacks up against the seven layer Open System Interconnection (OSI) protocol model.


TCP/IP version 4 (IPv4) addresses are made of up four 8-bit fields (octets) and are 32-bits in size total. Microsoft TCP/IP version 4 supports the standard classes of address, which defines which bits are used for the network ID and which bits are used for the host ID. There are five TCP/IP version 4 (IPv4) addresses, although for the most part, only the A, B, and C classes are used. The system of IP address classes described here form the basis for IP address assignment. Classless Inter-Domain Routing (CIDR) addressing is now being used more often, and I will cover that later in the article. Classless Inter-Domain Routing is making the IP address classes in their current form "less defined", for lack of a better term. Still, the classes form the base of any addressing scheme.

TCP/IP version 4 addresses are made of both a network ID and a host ID. The network ID address identifies the physical network where the hosts exist. The host ID address identifies the individual TCP/IP host on a network. The host ID must be unique on the internal network; that is, no two nodes on a given network can have the same network ID AND host ID.

[NOTES FROM THE FIELD] - You can have two hosts with the IP host name of 112.12.44 if one is on network 10 and another is on network 11. (The full IP addresses of these hosts would be 10.112.12.44& and 11.112.12.44. The subnet mask would be 255.0.0.0.) You cannot assign both of these nodes the host address of 112.12.44 if they are both on network 10 or both on network 11.

The "division" point between the network ID and the host ID is called the subnet mask. The subnet mask is used to determine where the network number in an IP address ends and the node number in an IP address begins.

The bits in a subnet mask are set consecutively from left to right and there can be no "skips" in the setting structure. The subnet mask of 255.255.128.0 is valid because all eight bits are set in the first two octets and the first bit of the next octet is also set. (11111111.11111111.10000000.00000000). The subnet mask of 255.255.64.0 is not valid because there is a "missing" bit that is not allowed. (11111111.11111111.01000000.00000000).

[NOTES FROM THE FIELD] - The left most bit in a TCP/IP version 4 address is called the Most Significant Bit (MSB) and has the highest value. The right most bit in a TCP/IP version 4 address is called the Least Significant Bit (LSB) and has the lowest value.

I have detailed subnet masks in a little more detail in the following section.

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