IP Address

Internet Structure – Larger networks Subnetwork: » Hosts IP address -What information should an IP address provide?

Mailing address: – State – City – Street address IP address: – Network address – Subnet address – Host address

IPv4 Example: 4 octets Total # of addresses available 256*256*256* 256= 4,294,967,296! Problem: 1.Only 256 networks? 2.What if the network only contains several subnets and less than 10 hosts in each subnet?

IPv4 Example: 4 octets Total # of addresses available 256*256*256* 256= 4,294,967,296! Problem: 1.Only 256 networks? 2.What if the network only contains several subnets and less than 10 hosts in each subnet?

Solution: classify networks into 3categories: Class A. Network address : first octet 1~127 examples: , Network administrator can assign addresses to their subnets and hosts using remaining three octets. Class B. Network address: first octet 128~191 and second octet examples: , Network administrator can assign addresses to their subnets and hosts using remaining two octets. Class C. Network address: first octet 192~223 and second, third examples: ,

Comparison of three types of networks ClassFirst octet Network address Host address Number of networks Number of addresses available for each network A1~127ab.c.d2 7 = = 16,777,216 B128~191a.bc.d2 14 = 16, = C192~223a.b.cd2 21 = 2,097, = 256

Are Billions of ip addresses enough for computers all over the world? – IPv4 addresses have already been exhausted in 2011! IPv6 – 128 bits in length IPv4 : 4 octets, each octet has 8 binary bits, total 32 bits IPv6: 8 components, each component has 16 binary bits, total 128 bits. – Capability: 2 128

Practice 1 – Consider you are a network administrator and you are monitoring the network communications. You captured packets from 5 different ip addresses, identify the faked addresses among them and classify the rest addresses into three categories( Class A, Class B,and Class C)

Practice 1 – Consider you are a network administrator and you are monitoring the network communications. You captured packets from 5 different ip addresses, identify the faked addresses among them and classify the rest addresses into three categories( Class A, Class B,and Class C) > >255

Practice 1 – Consider you are a network administrator and you are monitoring the network communications. You captured packets from 5 different ip addresses, identify the faked addresses among them and classify the rest addresses into three categories( Class A, Class B,and Class C)  class A 102 is among  class C 198 is among  class B 138 is among

Practice 2 – Providing a Class B network address, assume that the network administrator has set a subnet with network addresses ranging from * to *. Calculate number of addresses available in this subnet.

Practice 2 – Providing a Class B network address, assume that the network administrator has set a subnet with network addresses ranging from * to *. Calculate number of addresses available in this subnet. According to class B ip address format, the first two octets are fixed in this network, In each of the subnet segments specified by the third octet, there are 256 possible addresses, Example: ~ ~ #= 256* ( )=1280 addresses

Practice 3 – Assuming that you are arranging ip addresses for a company, the company has 3000 computers. Choose 1 class from the 3 classes (A, B and C ) for addressing; based on your choice, give a subnet range that can guarantee that every computer will have a valid and unique ip address.

Practice 3 – Assuming that you are arranging ip addresses for a company, the company has 3000 computers. Choose 1 class from the 3 classes (A, B and C ) for addressing; based on your choice, give a subnet range that can guarantee that every computer will have a valid and unique ip address. Class B network address: 0~2^16 different addresses # of subnet segments required= 3000/256=11.7~=12 The subnet segments (third octet) can be 0~11 or 9~20 or 210~221 or any 12 numbers with the values between 0~255.