How to set up TCP/IP

How to set up TCP/IP
(The really technical stuff)
This is the part that can be lengthy and confusing to explain about TCP/IP and how it works. You have to choose an IP address on your own, which can be difficult, but I will tell you how to do it. As you may know, an IP address is a grouping of four numbers that are each three or less numbers long, such as x.x.x.x where x is a number that is less than or equal to 255 down to 0 but not blank. The IP address that you see is a shorter way of writing a binary number that is 32 digits (bits) long.

Similar to a telephone number, an IP address is a way of finding something (for a phone, that something is a house, for IP, that is a computer). The more similar two numbers are from left to right, the more the two things have in common. As a phone number of 555-5555 is fairly similar to 555-4444; an IP address of 100.100.100.10 is fairly similar to an IP address of 100.100.100.20. As 444-5555 is not so similar to 222-2222; an IP address of 100.100.100.10 is not so similar to one of 200.200.200.10. To an even larger degree, as IP of 200.200.200.200 is not very similar at all to 100.100.100.100.

The differentiating factor between the slew of examples of IP addresses is the subnet that each would be on. On the simplest level, two IP addresses would be on the same subnet if both looked like 100.200.250.x. The x number can be anything, but if the 100, the 200, or the 250 are not in the same place on both numbers, then they are not on the same subnet.

As far as DCC is concerned, you should probably be sure that both IP addresses are on the same subnet.

On a slightly higher level, two addresses could share a subnet that look like 100.200.x.x. In this example, to IP's share a subnet as long as both IP's have the 100 and the 200 in common and in the same place.

The differentiating factor between these two examples (the ones with x or x.x on the same subnet) is the subnet mask. A subnet mask tells TCP/IP how much of two IP's must be similar in order to be within "shouting" distance. To be on the same subnet is to be withing shouting distance of another computer. If two computers are not on the same subnet, then a message has to be routed in order to get to its destination. A router would be a computer that is located between two subnets and gives a message from one subnet to the other subnet. The two subnets are not able to communicate directly. For DCC, you don't want routing.

Rembering that an IP address is really a 32 bit string of zero's and ones, let's look at what a subnet mask does.
I will make that statement that the two IP's of 100.100.100.100 and 100.100.100.50 are on the same subnet if the subnet mask is 255.255.255.0. Now I will explain how that is true.

First we need to look at IP addresses as a computer does.
100 in binary is 1100100 and
50 in binary is 110010. Therefore,

100.100.100.100=1100100.1100100.1100100.1100100
and
100.100.100.50= 1100100.1100100.1100100.110010.

If you count those digits you may get less than 32. That is just that 0100 is the same as 100.

Looking at these again with the subnet mask of 255.255.255.0,

01100100.01100100.01100100.01100100
01100100.01100100.01100100.00110010

11111111.11111111.11111111.00000000

then we see a relationship between where the 1's are in the mask and where it was important for the IP to have like numbers. Where there is a one in the subnet mask is where the parts of the IP numbers are checked to see if they are identical. Where the zero's lie is where the numbers do not matter.

Like an IP address, a subnet mask is a group of four numbers smaller than or equal to 255 Although any numbers can be used, it is most common that 255's or 0's are used. If you are doing it at home, use a simple mask like 255.255.255.0.

Hopefully that is enough that you can figure out anything else you need to know. That is the basic idea and if you want to know more, find a good book about it.

How to do it in Windows 95
(The simpler stuff)

After you have installed TCP/IP as a protocol, go to the Network Neighborhood and select the properties of "TCP/IP-> Dial-Up Adapter." From there, select the "IP Adress" tab. On this window you need to select the field for "Specify an IP address."

Fill in an address such as 100.100.100.100 on one computer and one such as 100.100.100.50 on the other computer. Be sure both have a subnet mask such as 255.255.255.0. (I guess 255.0.0.0 would work too.) Click OK and exit out of the Network Neighborhood and then restart the computers.

Both computers should now be ready to connect. (Provided you set up all the other stuff on the referring page.)

Notes about TCP/IP and DCC
When you assign an address to your Dial-up adapter, you are really assigning a static IP address to your modem. Generally you don't want to do this because your modem is assigned an address by your internet server every time you dial up. Usually a user doesn't always have the same IP address each time they dial up. This should create a problem for you and your ISP, but not having IP's is a problem for DCC. As a result, you can set up TCP/IP as you need for DCC, then reset them when you are finished DCC-ing.

When I tried dialing up with a static IP, I still got on and was assigned an IP address from my server, however, I was not able to connect to anything because Netscape was never able to find the DNS server to resolve host names. So I had one IP when not dialed up, and another when I did, then back to the original when I disconnected. *Strange*

By the way, if you make up IP addresses, keep in mind that you have to keep them at home. If you are on the net with a computer in which this would make a difference you would probably know this, but IP addresses that go public must be leased from the InterNIC. You can't make up any old number. (Judging from my experience, you can hard IP your dial-up adpater and still connect to the internet and recieve a server assigned IP.)

Along these lines, there are certain IP addresses that are "special" and shouldn't be used for DCC purposes. Some of those would be 255.255.255.255 and 0.0.0.0. The example of 100.100.100.100 would be ok.

When you network with ethernet cards, you set the IP address for them and you know it is for them. When setting up IP addressing for your dial-up adapter, on the other hand, you don't know exactly what that is. It is your modem, apparently, but it is also DCC, which has no modem. I am sure Windows uses some wierd feature with dial-up adapter that fools networking so that you can have an IP address, but it would be nice if you could set it up independent of the modem. Oh well.