Transcript IP Address
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: 2.32.126.78, 2.21.9.45 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: 138.92.74.211, 138.92.59.3 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: 217.168.1.4, 217.168.1.15 Comparison of three types of networks Class First octet Network address Host address Number of networks Number of addresses available for each network A 1~127 a b.c.d 27 = 128 224 = 16,777,216 B 128~191 a.b c.d 214 = 16,384 216 = 65536 C 192~223 a.b.c d 221 = 2,097,152 28 = 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: 2128 • 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). • • • • • 102.98.92.1 102.98.261.2 198.136.134 138.69.2.15 192.168.300.2 • 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). • • • • • 102.98.92.1 102.98.261.2 261>255 198.136.134 138.69.2.15 192.168.300.2 300>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). • • • • • 102.98.92.1class A 102 is among 0-127 102.98.261.2 198.136.134 class C 198 is among 192-223 138.69.2.15 class B 138 is among 128-191 192.168.300.2 • Practice 2 – Providing a Class B network address, assume that the network administrator has set a subnet with network addresses ranging from 181.46.12.* to 181.46.16.*. 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 181.46.12.* to 181.46.16.*. 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: 181.46.12.0~ 181.46.12.255 181.46.13.0~ 181.46.13.255 #= 256* (16-12+1)=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.