1. IP ADDRESSES History Classes and relation to first octet Subnetting Subnet mask Reserved Octets Special Classes IP address and Vlan

2. History Early computers were standalone devices. In the 1960s, the first interactive access to computers was brought about by time sharing. This was a conglomeration of data transmission technology and a teletypewriter.

3. History Cont. During the 1970s, an increased need for communications from computer to computer was apparent. Network design was geared toward the individual jobs that made up each working environment.

4. History Cont. When IP was first standardized in September 1981, the specification required that each system attached to an IP-based internet be assigned a unique, 32-bit Internet address value.

5. History Cont. 1983- The TCP/IP suite of networking protocols, or rules, becomes the only set of protocols used on the ARPANET. This decision sets a standard for other networks, and generates the use of the term "Internet" as the network of networks which either use the TCP/IP protocols or are able to interact with TCP/IP networks.

6. History Cont. 1989 - The backbone network is upgraded to "T1" which means that it is able to transmit data at speeds of 1.5 million bits of data per second, or about 50 pages of text per second.

7. Introduction to Classes In order to provide the flexibility required to support different sized networks, the designers decided that the IP address space should be divided into three different address classes – Class A, Class B, and Class C.

8. Introduction to Classes Each class fixes the boundary between the network-prefix and the host-number at a different point within the 32-bit address.

9. Class A Each Class A network address has an 8-bit network-prefix with the highest order bit set to 0 and a seven-bit network number, followed by a 24-bit host number. Example: 18.12.245.10

10. Class B Each Class B network address has a 16-bit network-prefix with the two highest order bits set to 1-0 and a 14-bit network number, followed by a 16-bit host number. Example: 144.26.108.15

11. Class C Each Class C network address has a 24-bit network-prefix with the three highest order bits set to 1-1-0 and a 21- bit network number, followed by an 8-bit host number. Example: 220.91.144.222

12. IP Class Summary

13. Subnetting Subnet Network segmented by network admin to provide a multilevel, hierarchical routing structure while shielding the subnet from the addressing complexity of attached networks. Subnets include network number, subnetwork number within the network, and a host number within the subnet. This 3 rd level of addressing provides extra flexibility. To create a subnet address A network administrator “borrows” bits from the host field and designates them as the subnet field. Any number of bits can be borrowed as long as two bits remain. Computers see subnetwork address in 3 parts Net.subnet.host

14. #Hosts to #Subnets

15. Formulas for finding #subnets and #hosts Amount of subnets 2 x – 2 = # of useable subnets Hosts per Subnet 2 (8 – x) – 2 = # of usable hosts per subnet X is the number of bits borrowed

16. Subnet mask Used to conceal subnet address from outside networks. A subnet mask is a 32 bit address mask used in IP addresses to indicate the number of the bits of an IP address that are being used for the subnet address. It’s function is to tell devices which part of an IP address is the subnet, and which part is the host. Subnet masks are found by adding up the total bits borrowed. Subnet masks for Class C addresses 2 bits – 255.255.255.192 3 bits – 255.255.255.224 4 bits – 255.255.255.240 5 bits – 255.255.255.248 6 bits – 255.255.255.252

17. Reserved Octets In Class A, the first octet must be saved for the network part. This class also always begins with 0-1 for the first two bits. In Class B, the first two must be used for the network portion of the address. The first two bits in this class are 1-0. Finally, in a Class C address, all but the last octet must be used for the network portion of the address. The first two bits in this class are 1-1.

18. Special Classes In addition to the three more commonly used classes. Class D is reserved for multicasting along all networks. The leading four bits are set to 1-1-1-0. Class E is used for experiments. The leading four bits are set to 1-1-1-1.

19. VLAN (Virtual Local Area Network) A virtual (or logical) LAN is a local area network with a definition that maps workstations on some other basis than geographic location (for example, by department, type of user, or primary application). The virtual LAN controller can change or add workstations and manage loadbalancing and bandwidth allocation more easily than with a physical picture of the LAN. Network management software keeps track of relating the virtual picture of the local area network with the actual physical picture. There are several approaches to implementing a VLAN. One of these is described in an official standard, IEEE 802.1Q.IEEE