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 Let me try to give you a short (it will not be very short) and simple introduction to TCP/IP. I will try to keep it as simple as possible (it may to be too simple for some of you, but if you need all the TCP/IP details, you need to go to your local bookstore and buy on of these books with 1000+ pages on TCP/IP). I will also not bother you with the history of TCP/IP and the Internet, unless required for the understanding of the setup.
IP-address:
Each Ethernet board worldwide has a unique Ethernet-address, it is a 48 bit number
(the first 24 bits indicate the manufacturer, the last 24 bits are a unique number for each
Ethernet board/controller-chip assigned by the manufacturer). This is also called the MAC-address.
When systems on a local area network ("LAN") are configured with NetBEUI or IPX/SPX protocol, they use these hardware-addresses to identify each other, so there is no need to define manually a network address.
But TCP/IP was designed as a Wide-area-network ("WAN"), able to continue to function, even if part of the network was not operating ( damaged or destroyed).
TCP/IP uses IP-addresses, which are 32-bit numbers. To make it easier to memorize such IP-addresses, they are usually expressed as 4 8-bit numbers (example: 192.168.10.1), where each of the 4 numbers is within the range of '0' to '255' (there are restriction on using '0' and '255', avoid using them.).
When setting up a small private network, you are free to use ANY IP-address, however, when you are connected to a company network, you need to ask the Network-administrator to assign you an IP-address. And if you are connected to the Internet, your ISP (Internet Service Provider) will assign an IP-address to you.
Even if a network is NOT connected to the Internet, it has become custom to use on private networks a range of IP-addresses, which are reserved for private networks (that makes it later possible to connect your private network to the Internet without having to re-configure everything). The reserved IP-address is: 192.168.x.y, where x=same number on all systems and y=different/unique number on all systems.
A small network of 3 systems would use:
You configure this IP-address in the properties of the TCP/IP-protocol:
(For now, simply enter as 'Subnet Mask" 255.255.255.0, it will be explained later in this document)
That's it, if you just like to connect systems on a small network, the network should work and you can test the Connection using the TCP/IP ping.
On a small network, you can still memorize the IP-addresses used, but if your network grows to 50+ systems, it becomes a serious management job. But TCP/IP offers some help by allowing to configure it to: "obtain an IP address automatically":
To be able to make this automatic assignment, there needs to be now on the network a database, keeping track of possible IP-addresses and to whom these addresses have been assigned:
DHCP (Dynamic Host Configuration Protocol)
On bootup, the system sends out a call on the network to find a DHCP-server, which assigns an IP-address to such a system. The IP-addresses are usually assigned NOT permanently, but for a specific time (could be days, weeks, months or on Internet-connections just for the ONE connection). If the system contacts the DHCP-server again during this time, the 'lease' on the IP-address is extended. But if you come back from a long vacation, your 'lease' of the IP-address may have expired, that IP-address may have been assigned now to somebody else, and you/your computer get now assigned a new IP-address.
Windows95 itself does NOT include any DHCP-server, you need to connect to a Windows NT (or similar class) server , which is configured as DHCP-server.
DHCP-server may also be buildin to some other products ( example : software Router for
Internet Connection Sharing ) .
If you are using/intend to use "obtain an IP address automatically", please do NOT reply
on it without verifying, that you did get an IP-address assigned. |
