Metric: contribution of packets of a given size to total packet and byte volumes
The following two graphs show the packet size distributions for a trace that was collected at FIX West on March 12, 1998 starting at 15:32 UTC and running for 7 minutes. The trace captured 5.7 million packets and over 2.6 GB of data.
Note that these results are directly comparable to the CAIDA paper presented at Inet 98[Claffy98a]. The results are quite similar to figures 3a and 3b in that paper despite the fact that the data came from a public exchange point rather than inside a private backbone.
figure 1: Packet size distribution for FIX west trace
figure 2: Cumulative packet size distrubtion for FIX west trace
Almost half of the packets are less than 44 bytes, another 18% are either 552 or 576 bytes. Almost 18% are 1500 bytes, with only a negligible number of packets larger than 1500 bytes. Note this difference in packet and byte distribution: while there are many teeny packets, they do not account for much of the overall payload: less than 5% of the bytes come in packets that could fit into a single 53 byte cell. Indeed, while over half of the packets are 44 bytes are less, over half of the byte volume is carried by 1500 byte packets.
Older data, collected in December 97 from the same measurement point, reflects similar statistics, although we seem to have more teeny packets now than before (HTTP has brought with it a lot of SYNs/ACKs, increased congestion has brought with it many retransmissions of same), but also more 1500 byte packets as links with larger MTU sizes become more prevalent in the network. In combination, the result is a growth in mean packet size.