Chapter 5 – IP Addressing

IP Address Fundamentals

• Each host is assigned a unique IP address for each network connection (NIC)

• An IP address is a 32-bit address, written as four octets (bytes) separated by periods

• Example: 195.143.67.2• This notation is called dotted decimal notation• Each address has an associated subnet mask tha divides

the address into its network and host components• The network portion identifies where the host is

located and host portion identifies device

IP Address Coordination

• IP Address assignments must be carefully coordinated

• Internet Network Information Center (InterNIC) is responsible for coordinating IP addresses

• To get an address, you may contact :– InterNIC Registration Services– C/o Network Solutions, Inc.– 505 Huntmar Park Drive– Herndon, VA. 22070– Hostmaster@internic.net

IP Address Classes

• Five address classes are supported (A-E)

• Only Classes A, B, and C are assigned to the general user community

• Class D is reserved for multicasting

• Class E is reserved for experimental purposes

Class A IP Address

• Leading octet starts with 0

• Subnet mask of 255.0.0.0

• Network range 1-126

• Number of networks: 126

• Number of hosts per network: 16,777,214

• All Class A addresses have been allocated

Class B IP Address

• Leading octet starts with 10• Subnet mask of 255.255.0.0• Network range: 128.0 – 191.255• Number of networks: 16,384• Number of hosts per network: 65,534• Class B addresses are hard to obtain• Mercer has a Class B (owned by Peachnet) that is

sublet to Mercer, Macon State, and UGA

Class C IP Address

• Leading octet starts with 110

• Subnet Mask of 255.255.255.0

• Network range: 192.0.0 – 223.255.255

• Number of networks: 2,097,152

• Number of hosts per network: 254

Class D IP Address

• Leading octet starts with 1110

• Network range: 224 – 239

IP Classes

• Note that the first octet tells you what class the IP address is in

• A: 1-126

• B: 128-191

• C: 192 – 223

• D: 224 – 239

Special IP Addressing

Network Field Host Field Destination

All Zeroes Host ID Host on this net

All ones All ones Local broadcast

Network ID All ones Directed broadcast

127 Anything Loopback

Use Windows Calculator to Convert Between Dec and Bin

• Open Windows calculator from the Accessories program group

• Under View, select Scientific

• Select Dec option

• Enter a decimal number

• Select Bin option to convert to binary

Concept of Subnetting

• Through subnetting, you can improve network efficiency

• Keeps local traffic local by keeping systems that need to share information together on their own subnet

• Makes job of setting up and managing routers easier

• Makes good use of assigned addresses

Subnetting Example

• Assume you have been assigned a Class B address of 155.110.0.0

• Default subnet mask is 255.255.0.0• You have the potential for 65,534 host all on the

same physical network• What to do if you want some subnets in your

network?• See Handout with Table: Class B Subnetting