TS Supplement (Includes RFC-1006 Support)

Introduction to the Tandem TCP/IP Subsystem

Introduction to RFC-1006

107751 Tandem Computers Incorporated 1–13

Figure 1-9. Internet Address Formats

045

Network

Address

Local Address

Class A Address

Note: Bit 0 is the most significant bit.

Bit

1 0

Network Address Local Address

Class B Address

Bit

1 1 0

Local Address

Class C Address

Bit

Network Address

0 8 16 24 31

To address subnets within a LAN, the LAN administrator can further divide the local

address into a subnet number that identifies a particular subnet and a host number

that identifies a host system within the subnet. The subnet number is always in the

most significant n bits of the local address (n varies depending on the address class).

Figure 1-10 shows an example of a class B address in which the first 5 bits of the local

address (bits 16 through 20) are designated as the subnet address, leaving the last 11

bits to identify the host (bits 21 through 31).

Figure 1-10. Internet Class B Address Format With a Subnet Address

050

Network Address

Internet

Address

Host Number

01516202131

Subnet

Number

Bit