The address space of IPv4 is 2 32 or 4,294,967,296. Binary notation:

Transcription

1 The address space of IPv4 is 2 32 or 4,294,967,296. Binary notation: Dotted-decimal notation: Hexadecimal Notation: D EA 0x75951DEA

2 Occupation of the address space In classful addressing, the address space is divided into five classes: A, B, C, D, and E.

3 Finding the class in binary notation

4 Finding the class in decimal notation For example, class B has min address (first byte) B = 128 D max address (first byte) B = 191 D

5 Netid and Hostid For example, class B has x 2 8 = 16,384 networks, Each network has (256 x 256) 2 = 65,534 hosts (addresses with host ID = all zeroes, or all 1s are not used for hosts)

6 Blocks in class A Net addresses 0, 10 and 127 are special and can t be given to organizations. 2 24

7 16 blocks are used for private addresses; only 2 6 x 2 8 = 16, = 16,368 netids can be assigned to networks Blocks in class B

8 Blocks in class C Class C has ( ) x 256 x 256 = 2,097,152 netids. However, 256 of these blocks are used for private addresses so only 2,097, = 2,096,896 (routable) netids can be assigned to networks. Each block can have = 254 hostids

9 Network Addresses The network address is the first address. For example the network address of is The network address defines the network to the rest of the Internet. Given the network address, we can find the class of the address, the block, and the range of the addresses in the block

10 Examples of network addresses

11 Question: Given the network address , find the class, the block, and the range of the addresses. Answer: The class is A because the first byte is between 0 and 127. The block has a netid of 17. The addresses range from to

12 Question: Given the network address , find the class, the block, and the range of addresses. Answer: The class is B because the first byte is between 128 and 191. The block has a netid of The addresses range from to

13 Question: Given the network address , find the class, the block, and the range of addresses. Answer: The class is C because the first byte is between 192 and 223. The block has a netid of The addresses range from to

14 Mask A mask is a 32-bit binary number that gives the first address in the block (the network address) when bitwise ANDed with an address in the block.

15 Multihomed devices Class A Class B Multihomed hosts or routers have more than one interface and more than one IP address (which are not necessarily of the same class)

16 Private Addresses A number of blocks in each class are assigned for private use. They are not recognized globally (not routable). Class Netids Blocks A B to C to Look familiar?

17 Special Addresses Type Netid Hostid Source/Dest Network address xxxxx Direct b/c address xxxxx Destination Limited b/c address Destination This host on this net Source Specific host on this net xxxxx Destination Loopback address 127 xxxxx Destination (b/c broadcast)

18 Example of direct broadcast address Destination

19 Example of limited broadcast address Destination

20 This host on this network Source Used by a host at boot time when it doesn t know its IP address

21 Specific host on this network Destination

22 Example of loopback address Doesn t propagate to data link layer.

23 Unicast, Multicast, and Broadcast Addresses Unicast communication is one-to-one. Multicast communication is one-to-many. Broadcast communication is one-to-all.

24 Example Network Token Ring IEEE 802.5; Class C Class B Ethernet IEEE 802.3; Class A

25 Problems 4(a) and 5(a): convert IP address from dotted decimal to binary and hexadecimal.

26 Problems 6(a): convert the IP address 0x1347FEAB in hexadecimal to binary notation.

27 Problems 12: Host sends a message to Does the message travel through a router?

28 Problems 14: Host sends a message to Does the message travel through a router?

29 Problems 15: Draw a diagram of a network with address that is connected through a router to a network with address Choose IP addresses for each interface of the router. Also show some hosts on each network with their IP addresses and address class.

30 Problems 20: A host in class C that does not know its IP address wants to send a packet to a bootstrap server to find its IP address. What are the source and destination addresses in the transmitted IP packet?

31 Problems 21: Can we have an address such as x.y.z.t/32?

32 Problems 22: In class A, the first address in a network (i.e. the network address) is What is the th address?

33 Problems 23: How many addresses are between and ?