Introduction to networking ( Yarnfield )

1. Introduction to networking(Yarnfield) IP addresses

2. Objectives • Define an IP address • Describe IP address classes • Describe network and host portions of an address • Describe what a broadcast address is used for • Describe what private IP addresses are used for

3. The Internet Protocol • Every machine MUST have a unique address • This is referred to as the IP address • This address is used to route packets of information using TCP/IP to a specific machine • The address is made up of two parts a network address and a host address • To find your IP address type ‘ipconfig’ into a command line window

4. The network part of the address • Is used to route the packet to the correct network • i.e. 194.66.170 would direct the packet to one part of the Staffordshire university network • Once the packet is within the network • The host part of the IP address is important to direct the packet to actual machine within that network • The network address size changes depending on the size of network in which the host is connected. • Class A, B, and C • All network addresses are issued by InterNIC (http://www.internic.net/) to ensure that all address attached to the Internet are unique

5. Host addresses

6. Address representation (IP v4) • An IP address is a 32 bit value • In theory this gives over 4 billion possible addresses • In reality the actual number of available addresses is a lot less than this • An IP address is represented by dotted decimal numbers • In reality within the network the values are represented by binary • As humans we do not use binary, as these are difficult for us to remember • Also it is very easy with a large number sequence to make mistakes when setting the IP address

7. Address classes • Address 127.*.*.* is a reserved address to indicate loop back • i.e. communicate with the device sending the request

8. Address classes

9. Address classes

10. Broadcast address • Is an IP address which is used when communications are required with ALL of the devices with a certain network address • This value is 255 in the host part of the address

11. Private IP addresses • A number of IP addresses have been reserved for private use on local LANS • If you setup a Microsoft windows network it will default to a class C private network IP address

12. Subnets • Subnets allow for a host part of a host address to indicate a subnet • These are smaller local networks within the major network • The advantage is that this allows a packet to be more tightly direct to a host • The disadvantage is valuable host addresses are used to create a subnet • More details about subnets will be given during the course

13. Subnet address • Also 32 bits in length • Indicates which part of the IP address is the network, and which part is the host • Each class has a default subnet mask • Class A - 255.0.0.0 • Class B - 255.255.0.0 • Class C - 255.255.255.0 • Example • 192.5.5.35 255.255.255.224 • 192.5.5.35/27 • You cannot skip bits!

14. Exercise • What are the two parts that make up an IP address? • What are the five classes of IP address, and which ones can be commercially used? • For an IPv4 IP address, how many bits are used and what is the total amount of addresses that can be derived? • What is the purpose of a subnet? • What will a broadcast IP address actually do?

15. Summary • IP addresses are used to route packets of data throughout a network • IPv4 uses 32 bits • Hierarchical in nature • Classes are A, B, C, D and E • Classes A, B and C are used commercially • Broadcast addresses reach all host machines on a network

16. Questions... • ...are there any?