1. IP ADDRESSING, SUBNETTING & VLSM 1

2. Decimal vs. Binary Numbers – Decimal numbers are represented by the numbers 0 through 9. – Binary numbers are represented by a series of 1s and 0s.

3. Binary Numbers Chart MSBLSB Base exponent 2727 2626 2525 2424 23232 2121 2020 Column Value11101001 Decimal Weight1286432168421 Column Value128643208001 Base-2 Binary Conversion—1110100 (233) 128 + 64 + 32 + 0 + 8 + 0 + 0 + 1 = 233

4. Powers of 2

5. Decimal-to-Binary Conversion 35=2 5 +2 1 +2 0 35= (32 * 1) + (2 * 1) + (1 * 1) 35 =0+0+1+0+0+0+1+1 35 = 00100011

6. Binary-to-Decimal Conversion 1 0 1 1 1 0 0 1 = ( 128 * 1 ) + ( 64 * 0 ) + ( 32 * 1 ) + ( 16 * 1 ) + ( 8 * 1 ) + ( 4 * 0 ) + ( 2 * 0 ) + ( 1 * 1 ) 1 0 1 1 1 0 0 1 = 128 + 0 + 32 + 16 + 8 + 0 + 0 + 1 1 0 1 1 1 0 0 1 = 185

7. Decimal and Binary Conversion

8. IP Addressing An IP address is a 32-bit sequence of 1s and 0s. To make the IP address easier to use, the address is usually written as four decimal numbers separated by periods. This way of writing the address is called the dotted decimal format.

9. IPv4 Addressing

10. Class A, B, C, D, and E IP Addresses

11. Reserved IP Addresses Certain host addresses are reserved and cannot be assigned to devices on a network. An IP address that has binary 0s in all host bit positions is reserved for the network address. An IP address that has binary 1s in all host bit positions is reserved for the broadcast.

12. Public and Private IP Addresses No two machines that connect to a public network can have the same IP address because public IP addresses are global and standardized. However, private networks that are not connected to the Internet may use any host addresses, as long as each host within the private network is unique. RFC 1918 sets aside three blocks of IP addresses for private, internal use. Connecting a network using private addresses to the Internet requires translation of the private addresses to public addresses using Network Address Translation (NAT).

13. IPv4 versus IPv6 IP version 6 (IPv6) has been defined and developed. IPv6 uses 128 bits rather than the 32 bits currently used in IPv4. IPv6 uses hexadecimal numbers to represent the 128 bits. IPv4

14. Mechanics of Subnetting

15. Classes of Network IP Addresses

16. Introduction to Subnetting Host bits must are reassigned (or “borrowed”) as network bits. The starting point is always the leftmost host bit. 3 bits borrowed allows 2 3 -2 or 6 subnets 5 bits borrowed allows 2 5 -2 or 30 subnets 12 bits borrowed allows 2 12 -2 or 4094 subnets Router(config)#ip subnet zero

17. Reasons for Subnetting High traffic volume can slow throughput time on a single segment network. Because each incoming and outgoing data packet is forced to search the entire range of IP addresses to find its assigned destination, there is a high collision rate when large volumes of traffic are competing for space across every node on the network. Higher collision rates create lost packets, higher latency and reduce overall transmission rates. Breaking down the network into smaller segments reduces the number of nodes any single packet contacts in its search for the proper destination. If, for example, the computers in the marketing department don't need to communicate directly with the computers on the manufacturing floor, both can be placed on separate segments. The result is an increase in throughput for both departments. Placing individual departments on individual subnets incidentally improves security as well. Because computers on one segment don't connect directly with other segments. One of the most common and compelling reasons to segment a network is when you are routing traffic for wide area network for a remote location(s). Setting up office communications for a single network in multiple locations requires subnets for effective operation. Minimizing unnecessary traffic between remote routers is a primary requirement for maintaining adequate transmission speed between locations

18. Establishing the Subnet Mask Address Determines which part of an IP address is the network field and which part is the host field. Follow these steps to determine the subnet mask: – 1. Express the subnetwork IP address in binary form. – 2. Replace the network and subnet portion of the address with all 1s. – 3. Replace the host portion of the address with all 0s. – 4. Convert the binary expression back to dotted- decimal notation.

19. Establishing the Subnet Mask Address To determine the number of bits to be used, the network designer needs to calculate how many hosts the largest subnetwork requires and the number of subnetworks needed. The “slash format” is a shorter way of representing the subnet mask: – /25 represents the 25 one bits in the subnet mask 255.255.255.128

20. Establishing the Subnet Mask Address Creating 8 Subnetwork

21. Subnetting Class A and B Networks The available bits for assignment to the subnet field in a Class A address is 22 bits while a Class B address has 14 bits.

22. Calculating the Subnetwork With ANDing ANDing is a binary process by which the router calculates the subnetwork ID for an incoming packet. – 1 AND 1 = 1; 1 AND 0 = 0; 0 AND 0 = 0 The router then uses that information to forward the packet across the correct interface. Packet Address192.168.10.6511000000.10101000.00001010.01000001 Subnet Mask255.255.255.22411111111.11111111.11111111.11100000 Subnetwork Address192.168.10.6411000000.10101000.00001010.01000000

23. Subnetting Review To identify subnets, you will “borrow” bits from the host ID portion of the IP address: – The number of subnets available depends on the number of bits borrowed. The available number of subnets = 2 s, I which s is the number of bits borrowed. – The number of hosts per subnet available depends upon the number of host ID bits not borrowed. The available number of hosts per subnet = 2 h -2, in which h is the number of host bits not borrowed. One address is reserved as the network address. One address is reserved as the broadcast address.

24. Possible Subnets and Hosts for a Class C Network

25. Possible Subnets and Hosts for a Class B Network

26. Possible Subnets and Hosts for a Class A Network

27. Subnetting Review Exercise Subnet a network with a private network address of 172.16.0.0./16 so that it provides 100 subnets and maximizes the number of host addresses for each subnet. – How many bits will need to be borrowed? – What is the new subnet mask? – What are the first four subnets? – What are the range of host addresses for the four subnets?

28. VLSM

29. What Is VLSM and Why Is It Used?

30. What Is a Variable-Length Subnet Mask? Subnet 172.16.14.0/24 is divided into smaller subnets. –Subnet with one mask (/27). –Then further subnet one of the unused /27 subnets into multiple /30 subnets.

31. A Waste of Space

32. When to Use VLSM?

33. Calculating Subnets with VLSM Allows up to 62 hosts per subnet Allows further 64 subnets

34. A Working VLSM Example (Cont.)