What are some of the basics regarding IP networking?
First, one must realize that the Internets IP address space is finite. This means that at the rate in which the Internet is growing there will not be enough IP’s for every device. For this reason a network administrator must learn how to properly manage their IP space. Before bringing up your network you should devise a plan for current and future needs. This plan should include breaking your address space into smaller chunks or blocks.
Think of your plan as building a house. Are there enough rooms, are they big enough, ect. Just like a house your well thought out IP schema will not change for a very long time.
Internet standards define five different classes of IP subnets. Class A - through Class E. The classes are broken down as follows:
- Class A ~ 0.1.0.0 - 126.0.0.0 | 16,777,216 addresses per network | Large enterprise networks
Class B ~ 128.0.0.0 - 191.255.0.0 | 65,536 addresses per network | Large networks
Class C ~ 192.0.1.0 - 223.255.255.0 | 256 addresses per network| Small networks
Class D ~ 224.0.0.0 - 239.255.255.255 | No addresses ** Multicast Only
Class E ~ 240.0.0.0 - 247.255.255.255 | No addresses ** Experimental use
Classful subnet masks are then applied to define the “network” and the “host”. For instance Class A has a subnet mask of 255.0.0.0, Class B 255.255.0.0 and Class C 255.255.255.0.
Classless addressing (RFC 1519) allows you go manipulate the IP schema any way you need. This is where your knowledge and planning comes in. You need to look at how many different subnets you will need on your network and the number of nodes for each subnet. Many people make the mistake of thinking they only need one subnet. Remember to think of possible future needs. Questions to ask are:
- Should I have a network management subnet (subnets for your routers)
Should I have a private subnet for databases that I only want certain nodes to access.
Should I have a backup subnet that keeps system backup traffic from degredating the public user traffic.
There are many reasons for having multiple subnets of different sizes. Take time to plan for any circumstance, both current and future. It is better to leave a good foundation to the person taking over for you than tossing them your problems.
Besides using Internet approved IP’s you may want to consider using addresses spaces that are not Internet approved. This means that you would use NAT to translate private addresses into Internet approved addresses. This will greatly decrease the number of IP’s you need to reserve which are Internet approved. RFC 1918 discusses how you can freely use private addresses in your internal network. Implementing NAT and private IP’s will allow you to grow your network to an extremely large scale.
For more indepth understanding of IP networking basics it is recommended that you search online articles and RFC’s for VLSM (Variable length subnet masking), Classful vs. classless routing, routing protocols, subnet masking, understanding binary.