5-1

Chapter 5

Viewing IP Group Statistics

The IP Group window; using the Time To Live option

The Internet Protocol (IP) is the protocol used in the Internet layer. Each IP
datagram contains identifying information such as the datagram’s originator, the
datagram’s length, the format used (version), and the quality of service.
Each medium has a maximum size data field used to encapsulate an IP datagram
(Maximum Transmit Unit or MTU). When a local IP entity (the device) wishes to
send a datagram larger than the allowable maximum size, it must first fragment
the datagram prior to transmission. The IP entity checks to see if the flags field in
the datagram permits fragmentation. (If it does not, the datagram is discarded.) It
then generates two or more fragments that contain a portion of the user -data f rom
the original datagram.
These fragments are reassembled at the destination IP address. If they arrive out
of order (since they may be routed over different paths), they are held (buffered)
until all fragments of the original datagram have arrived. Should the fragments
become lost or corrupted during transmission, then they are discarded.
The IP Group window provides a statistical breakdown of the number of
datagrams received by, and transmitted from the device. Also included are the
various types of fragmented and reassembled datagrams.
To open the IP Group window from the System Group window:
1. Click on the Other Groups button. The Other Groups drop-down menu
displays.
2. Click on IP Group. The IP Group window, Figure5-1, opens.