IP Addressing Higher Computing

TCP/IP TCP/IP is the communication protocol for the internet. TCP/IP is the communication protocol for the internet. TCP/IP defines the rules computers must follow to communicate with each other over the internet. TCP/IP defines the rules computers must follow to communicate with each other over the internet.

TCP/IP Allows computers on different networks to communicate with each other. Allows computers on different networks to communicate with each other. The computers could be on different LANs in the same building or on two LANs in different countries. The computers could be on different LANs in the same building or on two LANs in different countries.

Browsers and Servers Browsers and servers use TCP/IP to connect to the Internet. Browsers and servers use TCP/IP to connect to the Internet. A browser uses TCP/IP to access a server. A browser uses TCP/IP to access a server. A server uses TCP/IP to send HTML back to a browser. A server uses TCP/IP to send HTML back to a browser.

TCP/IP TCP/IP stands for Transmission Control Protocol / Internet Protocol. TCP/IP stands for Transmission Control Protocol / Internet Protocol. TCP/IP defines how electronic devices (like computers) should be connected to the Internet, and how data should be transmitted between them. TCP/IP defines how electronic devices (like computers) should be connected to the Internet, and how data should be transmitted between them.

TCP/IP TCP is responsible for breaking data down into IP packets, giving each packet a sequence number and for assembling the packets when they arrive. TCP is responsible for breaking data down into IP packets, giving each packet a sequence number and for assembling the packets when they arrive. IP is responsible for sending the packets to the correct destination. IP is responsible for sending the packets to the correct destination.

IP Addressing Each computer must have an IP address before it can connect to the Internet. Each computer must have an IP address before it can connect to the Internet. Each IP packet must have an address before it can be sent to another computer. Each IP packet must have an address before it can be sent to another computer.

Structure of IP addresses IP address is a 32-bit number made up of four parts called octets IP address is a 32-bit number made up of four parts called octets Usually displayed as four decimal numbers, e.g. Usually displayed as four decimal numbers, e.g Each octet must be in the range of 0 to 255. Each octet must be in the range of 0 to and 255 are set aside for special purposes 0 and 255 are set aside for special purposes

Possible number of IP addresses An IP address is 32 bits long. An IP address is 32 bits long. This means that there are 2 32 possible IP addresses, approx 4.3 billion. This means that there are 2 32 possible IP addresses, approx 4.3 billion. However… However…

Public/Private IP addressing Computers on private LANs do not need a public IP addresses, since they do not need to be accessed by the public. Computers on private LANs do not need a public IP addresses, since they do not need to be accessed by the public. Therefore, certain addresses that will never be registered publicly are reserved. These are known as private IP addresses, and are found in the following ranges: Therefore, certain addresses that will never be registered publicly are reserved. These are known as private IP addresses, and are found in the following ranges: From to From to From to From to From to From to

Public/Private IP addressing Devices with private IP addresses cannot connect directly to the Internet Devices with private IP addresses cannot connect directly to the Internet Computers outside the network cannot access devices with a private IP address. Computers outside the network cannot access devices with a private IP address. Access must be obtained through a router. Access must be obtained through a router.

Static IP addressing A static IP address is where the computers are given a fixed IP address that never changes. A static IP address is where the computers are given a fixed IP address that never changes. The computer always keeps the same address every time it connects to the Internet. The computer always keeps the same address every time it connects to the Internet.

Dynamic IP addressing There are only a limited number of IP addresses. ISPs use dynamic IP addressing to get around the problem. There are only a limited number of IP addresses. ISPs use dynamic IP addressing to get around the problem. A dynamic IP address is when computers on a network are given an IP address when they are connected to the network for that session. It can change each time they are connected. A dynamic IP address is when computers on a network are given an IP address when they are connected to the network for that session. It can change each time they are connected.

Benefits of Dynamic IP addressing Less security risk- computer is assigned a new IP address each time you connect to a network. Less security risk- computer is assigned a new IP address each time you connect to a network.

Classes of IP addresses There are 4 classes of IP addresses: There are 4 classes of IP addresses: Class A Class A Class B Class B Class C Class C Class D Class D

Classes of IP addresses Different classes of IP addresses are achieved by splitting the octets into two parts called the network identifier and the node identifier. Different classes of IP addresses are achieved by splitting the octets into two parts called the network identifier and the node identifier. Network identifier = n Network identifier = n Node identifier = h Node identifier = h

Classes of IP addresses The network identifier is used to route packets to the destination network. The network identifier is used to route packets to the destination network. On arrival at the network, the host identifier is used to route packets to the individual computer. On arrival at the network, the host identifier is used to route packets to the individual computer.nnn.nnn.hhh.hhh NetworkNode

Class A Class A addresses are structured as follows: Class A addresses are structured as follows: nnn.hhh.hhh.hhh nnn.hhh.hhh.hhh The first octet will be in the range of 1 to 126 and identifies the network The first octet will be in the range of 1 to 126 and identifies the network The remaining three octets will identify the nodes on that network. The remaining three octets will identify the nodes on that network. This allows for 16, 277, 214 addresses. ( ) This allows for 16, 277, 214 addresses. ( )

Class B Class B addresses are structured as follows: Class B addresses are structured as follows: nnn.nnn.hhh.hhh nnn.nnn.hhh.hhh The first octet will be in the range of 128 to 191. The first octet will be in the range of 128 to 191. The first two octets identify the network. The first two octets identify the network. The remaining octets identify the nodes on that network The remaining octets identify the nodes on that network This allows for 65,534 addresses. (2 16 – 2) This allows for 65,534 addresses. (2 16 – 2)

Class C Class C addresses: Class C addresses: nnn.nnn.nnn.hhh nnn.nnn.nnn.hhh The first octet is in the range of 192 to 223. The first octet is in the range of 192 to 223. The first three octets identify the network. The first three octets identify the network. The last octet identifies the nodes on that network. The last octet identifies the nodes on that network. This allows for 254 different addresses (2 8 – 2) This allows for 254 different addresses (2 8 – 2)

Class D These are not used for networks, but for multicast messaging. These are not used for networks, but for multicast messaging. The first octet will be in the range of 224 to 255. The first octet will be in the range of 224 to 255.