At 11:54 AM 12/8/00 -1000, Uyeshiro, Robin wrote:
I am evaluating an IP in IP encapsulation technology and would like to know
the average size or size range of an IP Packet, including the 20 byte header.
Can you tell me this or where to find it?
various studies in various places have come up with different answers. It
depends on who is using what part of the net for what purpose, what
applications he is using, and what sized files he's moving around.
The general observation is that:
- TCP represents 90-95% of the traffic on the net
- TCP Acknowledges are among the most common packets in the net: 40 bytes
- TCP SYN and SYN-ACK happens for each TCP session: 44 bytes
- Once a transmission occupies two segments, one of them will be MSS-sized;
that will be either 512 data bytes plus TCP and IP headers (552), or
it will approximate the MTU on one of the links en route (usually
~1500)
- The last packet in the train will be random sized. There will be at
least one such per direction per session established.
So in general, you get one Ack for each two data segments somebody sends,
and a lot of web sessions will have only one data packet each way. TCP
control messages are variously reported, but seem to be around 30-40% of
total traffic. Random sized packets are perhaps a quarter of traffic to a
third, and MSS/MTU sized packets are the rest.
The average of the above is generally in the 200-250 bytes per packet
neighborhood, largely due to the predominance of 552 byte segments. If Path
MTU were more widely used - something one would expect to happen as systems
are upgraded over time - this likely would grow to upper hundreds.
That is an over-the-thumb summary of a lot of different traffic captures
(including but not limited to CAIDA captures) I have looked at or read
about, and should be treated as appropriately fuzzy.