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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)                 9  Internet Protocol Version 4 (IP, IPv4)                      9  IP Addressing                           9  IP Subnetting: Practical Subnet Design and Address Determination Example

IP Subnetting Step #4: Determining Subnet Identifiers and Subnet Addresses 1 2 3 IP Classless Addressing: Classless Inter-Domain Routing (CIDR) / "Supernetting"

Class B Host Address Determination Example

We can do the same thing for our Class B network, naturally. The address of that network is 166.113.0.0. Now, say we want to define the hosts that go in subnet #13. We substitute 13 in binary (01101) for the subnet ID bits, to get the following subnet address, shown with the subnet ID bits highlighted and the host ID bits highlighted and underlined:

10100110 01110001 01101000 00000000

This is the subnet address 166.113.104.0. Now, we have 11 bits of host ID, so we can have a maximum of 2,046 hosts. The first is found by substituting “000 00000001” for the host ID bits”, to give an address of 166.113.104.1. The second host is 166.113.104.2, and so on. The last is found by substituting “111 11111110”, to give an address of 166.113.111.254. Note that since the host ID bits extend over two octets, two octets change as we increment the host ID, unlike our Class C example. The broadcast address is 166.113.111.255.

IP Subnetting Step #4: Determining Subnet Identifiers and Subnet Addresses 1 2 3 IP Classless Addressing: Classless Inter-Domain Routing (CIDR) / "Supernetting"