Windows Server® 2008 TCP/IP Protocols and Services

The IP Datagram

Figure 5-1 shows the structure of an IP datagram.

The IP datagram consists of the following:

• IP header. The IP header is of variable size, between 20 and 60 bytes, in 4-byte increments. It provides routing support, payload identification, IP header and datagram size indication, fragmentation support, and options.

  

  Figure 5-1. The structure of the IP datagram at the Network Interface layer

• IP payload. The IP payload is of variable size, ranging from 0 bytes (a 20-byte IP datagram with a 20-byte IP header) to 65,515 bytes (a 65,535-byte IP datagram with a 20byte header).

As sent on a link, the IP datagram is wrapped with a Network Interface ...