Introduction

The total transmission time of the original packet is the time between the monitoring of the first packet belonging to the fragment series and the monitoring of the last packet belonging to the fragment series. This is usually, but no tinvariably, the last packet in the series. Some fragment series are monitored out of order, for reasons including the fragments being routed along different paths up until they cross the link we monitor.

Analysis

The link we monitor at the Ames Internet Exchange is load-balanced -- our monitor captures only a fraction of the traffic through AIX. Since individual packets can be routed through any of the links at AIX, and not necessarily the link our monitor can "see", we see far fewer complete fragment series. 93.0 percent of the fragments monitored on the UCSD-CERF link are members of a complete series, compared to between 9.6 and 10.8 percent of the fragments at AIX. The time it takes to transmit the original packet is independent of the number of packets in the series. It is influenced by the line rate of the router that performed the fragmentation, the length of time the packets were queued in intermediate routers, and fragments ending up in different priority queues in an intermediate router. The magnitude and nature of these influences has yet to be quantified.

frag_cerf_2000-05-17_12-11

This trace was taken on the UCSD-CERF link from Wed May 17 14:40:39 PDT 2000 to Fri Jun 2 20:42:48 PDT 2000. 50,375,114 packets containing 50,945,519,628 bytes of data composing 19,054,937 fragment series were captured in this interval. Of those, 17,718,285 (93.0%) were complete series.

aix_frag_958848611

This trace was taken from the Ames Internet Exchange from Sat May 20 11:50:42 PDT 2000 to Tue May 23 23:04:01 PDT 2000. 9,781,240 packets containing 11,406,413,861 bytes of data composing 7,183,794 series fragment series were captured in this interval. Of those, 692,184 (9.6%) were complete series.

aix_frag_959148226

This trace was taken from the Ames Internet Exchange from Tue May 23 23:04:17 PDT 2000 to Fri May 26 11:00:28 PDT 2000. 8,599,458 packets containing 9,327,540,025 bytes of data composing 6,922,673 fragment series were captured in this interval. Of those, 747,401 (10.7%) were complete series.

aix_frag_959364017

This trace was taken from the Ames Internet Exchange from Fri May 26 11:00:48 PDT 2000 to Wed May 31 00:27:38 PDT 2000. 12,273,208 packets containing 13,645,419,937 bytes of data composing 9,832,899 fragment series were captured in this interval. Of those, 1,069,074 (10.8%) were complete series.