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About Packet Fragmentation...
Packet fragmentation occurs when a packet too large for the subsequent link reaches a network interface and is broken up into a series of fragments the size of the MTU of the ensuing link. Packet fragmentation has a negative impact on network performance for several reasons. First, a router has to perform the fragmentation - an expensive operation. Second, all the routers in the path between the router performing the fragmentation and the destination have to carry additional packets with the requisite additional headers.
Glossary
- Packet:
- A discrete unit consisting of data that needs to be transported across a network and information necessary to direct that data to its destination.
- Payload:
- The data that needs to be transported across a network.
- IP header:
- Information prepended to the payload that allows the payload to reach its destination, including the source and destination and a checksum for error detection.
- MTU:
- Maximum Transmission Unit -- the largest size of packet that can be transported across a given link.
- Path MTU:
- The smallest MTU of all the links in a path.
- Fragment:
- When a fragment is larger then the next link, it is broken up into pieces called 'fragments' that are no larger than the MTU of the next link.
- Fragment Series:
- The set of fragments that composed a single original packet.
The following pages contain graphs and analysis of fragmented packet traffic on several links:
Analysis by Trace
- UCSD-CERF
- The Poster I presented at the SDSC Student Intern Poster Session. (contains data from several traces)
- May 17-June2, 2000
- Ames Internet Exchange
- Coming Soon!
- Analysis by Data Type
- Fragments per Fragment Series
- Sizes of Fragment Series
- First Fragment Sizes
- Last Fragment Sizes
- Original Packet Transmission Time