Packet Fragmentation And Reassembly; Arp - D-Link DES-3326 User Manual

DES-3326 Layer 3 Fast Ethernet Switch User's Guide

Packet Fragmentation and Reassembly

TCP/IP can be used with many different types of networks, but not
all network types can handle the same length packets.
When IP is transmitting large files, large packets are much more
efficient than small ones. It is preferable to use the largest
possible packet size, but still be able to cross networks that require
smaller packets.
To do this, IP can 'negotiate' packet size between the local and
remote ends of a connection. When an IP connection is first made,
the IPs at both ends of the connection state the largest packet they
can handle. The smaller of the two is selected.
When a IP connection crosses multiple networks, it is possible that
one of the intermediate networks has a smaller packet size limit
than the local or remote network. IP is not able to determine the
maximum packet size across all of the networks that may make up
the route for a connection. IP has, therefore, a method to divide
packets into multiple, smaller packets to cross such networks. This
division of large packets into smaller packets is referred to as
fragmentation.
A field in the TCP header indicates that a packet has been
fragmented, and other information aids in the reassembly of the
packets into the original data.
Gateways that connect networks of different packet size limits split
the large packets into smaller ones and forward the smaller
packets on their attached networks.

ARP

The Address Resolution Protocol (ARP) determines the MAC
address and IP address correspondence for a network device.
Switch Management and Operating Concepts
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