Chapter 4 IP Addressing Classful Addressing Kyung Hee

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Chapter 4 IP Addressing : Classful Addressing Kyung Hee University 1

Chapter 4 IP Addressing : Classful Addressing Kyung Hee University 1

4. 1 Introduction o. For a host to communicate with any other host Need

4. 1 Introduction o. For a host to communicate with any other host Need a universal identification system Need to name each host o. Internet address or IP address is a 32 -bit address that uniquely defines a host or a router on the internet o. The IP addresses are unique in the sense that two devices can never have the same address. However, a device can have more than one address. Kyung Hee University 2

Notation o Binary notation 01110101 10010101 00011101010 32 bit address, or a 4 octet

Notation o Binary notation 01110101 10010101 00011101010 32 bit address, or a 4 octet address or a 4 -byte address o Decimal point notation Kyung Hee University 3

Notation (cont’d) o Hexadecimal Notation 0111 0101 1001 0101 0001 1110 1010 75 95

Notation (cont’d) o Hexadecimal Notation 0111 0101 1001 0101 0001 1110 1010 75 95 1 D EA 0 x 75951 DEA - 8 hexadecimal digits - Used in network programming Kyung Hee University 4

4. 2 Classful Addressing o Occupation of address space In classful addressing, the address

4. 2 Classful Addressing o Occupation of address space In classful addressing, the address space is divided into five classes: A, B, C, D, and E. Finding the class in binary notation Kyung Hee University 5

Classful Addressing (cont’d) Finding the address class Kyung Hee University 6

Classful Addressing (cont’d) Finding the address class Kyung Hee University 6

Classful Addressing (cont’d) l Finding the class in decimal notation Kyung Hee University 7

Classful Addressing (cont’d) l Finding the class in decimal notation Kyung Hee University 7

Netid and Hostid o. Each IP address is made of two parts; netid and

Netid and Hostid o. Each IP address is made of two parts; netid and hostid. o. Netid defines a network; hostid identifies a host on that network. Kyung Hee University 8

Netid and Hostid (cont’d) o IP addresses are divided into five different classes: A,

Netid and Hostid (cont’d) o IP addresses are divided into five different classes: A, B, C, D, and E Kyung Hee University 9

Classes and Blocks o Blocks in class A Class A is divided into 128

Classes and Blocks o Blocks in class A Class A is divided into 128 blocks with each block having a different netid. Millions of class A addresses are wasted. Kyung Hee University 10

Classes and Blocks (cont’d) o Class B is divided into 16, 384 blocks with

Classes and Blocks (cont’d) o Class B is divided into 16, 384 blocks with each block having a different netid Many class B addresses are wasted. Kyung Hee University 11

Classes and Blocks (cont’d) o Class C is divided into 2, 097, 152 blocks

Classes and Blocks (cont’d) o Class C is divided into 2, 097, 152 blocks with each block having a different netid The number of addresses in a class C block is smaller than the needs of most organizations Kyung Hee University 12

Classes and Blocks (cont’d) o Class D addresses are used for multicasting; there is

Classes and Blocks (cont’d) o Class D addresses are used for multicasting; there is only one block in this class. o Class E addresses are reserved for special purposes; most of the block is wasted. Kyung Hee University 13

Network Address o The network address is the first address. o. The network address

Network Address o The network address is the first address. o. The network address defines the network to the rest of the Internet. o Given the network address, we can find the class of the address, the block, and the range of the addresses in the block o In classful addressing, the network address (the first address in the block) is the one that is assigned to the organization. Kyung Hee University 14

Mask o A mask is a 32 -bit binary number that gives the first

Mask o 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. o Masking concept Kyung Hee University 15

Mask (cont’d) o AND Operation o The network address is the beginning address of

Mask (cont’d) o AND Operation o The network address is the beginning address of each block. It can be found by applying the default mask to any of the addresses in the block (including itself). It retains the netid of the block and sets the hostid to zero. (refer table 4. 2) Kyung Hee University 16

Default Masks Table 4. 2 Default masks Kyung Hee University 17

Default Masks Table 4. 2 Default masks Kyung Hee University 17

4. 3 Others Issues o Multihomed devices (computers, or routers) A computer that is

4. 3 Others Issues o Multihomed devices (computers, or routers) A computer that is connected to different networks Having more than one address Kyung Hee University 18

Special Addresses o Some parts of the address space in class A, B, C

Special Addresses o Some parts of the address space in class A, B, C for special addresses Table 4. 3 Special addresses Kyung Hee University 19

Special Addresses o Network address : an address with the hostid all set to

Special Addresses o Network address : an address with the hostid all set to 0 s Kyung Hee University 20

Special Addresses (cont’d) o Direct Broadcast Address : Used by a router to send

Special Addresses (cont’d) o Direct Broadcast Address : Used by a router to send a packet to all hosts in a specific network Kyung Hee University 21

Special Addresses (cont’d) o Limited Broadcast Address : all 1 s for the netid

Special Addresses (cont’d) o Limited Broadcast Address : all 1 s for the netid and hostid (32 bits) Kyung Hee University 22

Special Addresses (cont’d) o This Host on This Network : used by a host

Special Addresses (cont’d) o This Host on This Network : used by a host at bootstrap time when it does not know its IP address Kyung Hee University 23

Special Addresses (cont’d) o Specific Host on This Network : used by a host

Special Addresses (cont’d) o Specific Host on This Network : used by a host to send a message to another on the same network Kyung Hee University 24

Special Addresses (cont’d) o Loopback Address : IP address of the first byte :

Special Addresses (cont’d) o Loopback Address : IP address of the first byte : 127 Used to test the software on a machine Used by a client process to send a message to a server process on the same machine “Ping” Kyung Hee University 25

Private Addresses o A number of blocks in each class are assigned for private

Private Addresses o A number of blocks in each class are assigned for private use. They are not recognized globally. Class Netid Total Class A 10. 0. 0 1 Class B 172. 16 to 172. 31 16 Class C 192. 68. 0 to 192. 68. 255 256 Kyung Hee University 26

Unicast, Multicast, and Broadcast Addresses o Unicast communication is one-to-one. o Multicast communication is

Unicast, Multicast, and Broadcast Addresses o Unicast communication is one-to-one. o Multicast communication is one-to-many. o Broadcast communication is one-to-all. Kyung Hee University 27

Unicast, Multicast, and Broadcast Addresses (cont’d) o Assigned Multicast addresses : starting with a

Unicast, Multicast, and Broadcast Addresses (cont’d) o Assigned Multicast addresses : starting with a 224. 0. 0 prefix http: //www. iana. org/assignments/multicast-addresses Table 4. 5 Category addresses Kyung Hee University 28

Unicast, Multicast, and Broadcast Addresses (cont’d) o. Unicast Addresses : one-to-one o. Multicast addresses

Unicast, Multicast, and Broadcast Addresses (cont’d) o. Unicast Addresses : one-to-one o. Multicast addresses : one-to-many; class D address Used as a destination address Kyung Hee University 29

Unicast, Multicast, and Broadcast Addresses (cont’d) o Multicast address for conferencing : starting with

Unicast, Multicast, and Broadcast Addresses (cont’d) o Multicast address for conferencing : starting with a 224. 0. 1 prefix Table 4. 6 Addresses for conferencing Kyung Hee University 30

Unicast, Multicast, and Broadcast Addresses (cont’d) o. Broadcast addresses : one-to-all Allowed only at

Unicast, Multicast, and Broadcast Addresses (cont’d) o. Broadcast addresses : one-to-all Allowed only at the local level l Limited broadcast address (all 1 s) l Direct broadcast address (netid: specific, hostid: all 0 s) No broadcasting is allowed at the global level Kyung Hee University 31

A Sample Internet with Classful Address o Token Ring LAN (Class C), Ethernet LAN

A Sample Internet with Classful Address o Token Ring LAN (Class C), Ethernet LAN (Class B), Ethernet LAN (Class A) , Point-to-point WAN, A Switched WAN Kyung Hee University 32

4. 4 Subnetting and Supernetting o. Subnetting A network is divided into several smaller

4. 4 Subnetting and Supernetting o. Subnetting A network is divided into several smaller networks with each subnetwork (or subnet) having its subnetwork address o. Supernetting Combining several class C addresses to create a larger range of addresses o IP Addresses are designed with two levels of hierarchy Kyung Hee University 33

Subnetting o Classes A, B, C in IP addressing are designed with two levels

Subnetting o Classes A, B, C in IP addressing are designed with two levels of hierarchy (not subnetted) Netid and Hostid Kyung Hee University 34

Subnetting (cont’d) o Further division of a network into smaller networks called subnetworks o

Subnetting (cont’d) o Further division of a network into smaller networks called subnetworks o R 1 differentiating subnets Kyung Hee University 35

Subnetting (cont’d) o Three levels of hierarchy : netid, subnetid, and hostid Kyung Hee

Subnetting (cont’d) o Three levels of hierarchy : netid, subnetid, and hostid Kyung Hee University 36

Subnetting (cont’d) o. Three steps of the routing for an IP datagram Delivery to

Subnetting (cont’d) o. Three steps of the routing for an IP datagram Delivery to the site, delivery to the subnetwork, and delivery to the host o. Hierarchy concept in a telephone number 031 Kyung Hee University 37

Subnet Mask o A process that extracts the address of the physical network (network/subnetwork

Subnet Mask o A process that extracts the address of the physical network (network/subnetwork portion) from an IP address Kyung Hee University 38

Finding the Subnet Mask Address o Given an IP address, we can find the

Finding the Subnet Mask Address o Given an IP address, we can find the subnet address the same way we found the network address in the previous chapter. We apply the mask to the address. we use binary notation for both the address and the mask and then apply the AND operation to find the subnet address. o Example 15 What is the subnetwork address if the destination address is 200. 45. 34. 56 and the subnet mask is 255. 240. 0? Kyung Hee University 39

Finding the Subnet Mask Address (cont’d) o. Solution 11001000 00101101 0010 00111000 111111110000 11001000

Finding the Subnet Mask Address (cont’d) o. Solution 11001000 00101101 0010 00111000 111111110000 11001000 00101101 00100000 The subnetwork address is 200. 45. 32. 0. Kyung Hee University 40

Comparison of a default mask and a subnet mask o Kyung Hee University 41

Comparison of a default mask and a subnet mask o Kyung Hee University 41

Supernetting o. A block of class x addresses o. For example, An organization that

Supernetting o. A block of class x addresses o. For example, An organization that needs 1, 000 addresses can be granted four class C addresses Kyung Hee University 42

Supernetting (cont’d) o 4 class C addresses combine to make one supernetwork Kyung Hee

Supernetting (cont’d) o 4 class C addresses combine to make one supernetwork Kyung Hee University 43

Supernet Mask o. In subnetting, we need the first address of the subnet and

Supernet Mask o. In subnetting, we need the first address of the subnet and the subnet mask to define the range of addresses. o In supernetting, we need the first address of the supernet and the supernet mask to define the range of addresses. Kyung Hee University 44

Supernet Mask (cont’d) o Comparison of subnet, default, and supernet masks Kyung Hee University

Supernet Mask (cont’d) o Comparison of subnet, default, and supernet masks Kyung Hee University 45

Summary o At the Network layer, a global identification system that uniquely identifies every

Summary o At the Network layer, a global identification system that uniquely identifies every host and router is necessary for delivery of packet from host to host. o An IPv 4 address is 32 bits long and uniquely and universally defines a host or router on the Internet. o The portion of the IP address that identifies the net o The portion of the IP address that identifies the host or router on the network is called the hosted work is called the netid. o An IP address defines a device’s connection to a network. o There are five classes in IPv 4 addresses. Classes A, B, and C differ in the number of hosts allowed per network. Class D is for multicasting and Class E is reserved. Kyung Hee University 46

Summary o The class of an address is easily determined by examination of the

Summary o The class of an address is easily determined by examination of the first byte. o Addresses in classes A, B, or C are mostly used for unicast communication. o Address in class D are used for multicast communication. o Subnetting devides on large network into several smaller ones, adding an intermediate level of hierarchy in IP addressing. o Classes A, B and C addresses can be subnetted. o Supernetting combines several networks into one large one. Kyung Hee University 47

Q and A Kyung Hee University 48

Q and A Kyung Hee University 48