Amer Networks SS3GR24i - Manual (Page 43)

SS3GR24i/SS3GR48i Layer3 Stackable Gigabit Switch User’s Guide
IP
TCP sends its packets to IP with the source and destination IP
addresses. IP is only concerned with these IP addresses. It is not
concerned with the contents of the packet or the TCP header.
IP finds a route for the packet to get to the other end of the TCP
connection. IP adds its own header to the packet to accomplish
this.
The IP header contains the source and destination addresses, the
protocol number, and another checksum.
The protocol number tells the receiving IP which protocol to give
the packet to. Although most IP traffic uses TCP, other protocols
can be used (such as UDP).
The checksum is used by the receiving IP in the same way as the
TCP checksum.
Figure 5-2. IP Packet Header
The flags and fragment offset are used to keep track of packets
that must be divided among several smaller packets to cross
networks for which they are too large.
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