WITS: Local ISP A-II

Trace Format PCAP file captured using tcpdump.
Volume on Disk 3 GB
Number of Traces 4
Capture Start (Local) Fri Dec 10 16:09:05 1999
Capture End (Local) Fri Dec 17 14:51:48 1999
Total Duration 6 Days, 11 Hours, 16 Minutes and 0 Seconds
Packets Captured 75 million
Total Traffic 24 GB
Contiguity First three traces are contiguous - the last trace is standalone.
Snapping Method tcpdump snaplen set to 120 bytes.
Rotation Policy File is rotated every 2 million packets.
Anonymization None

This is a collection of traces taken at a New Zealand ISP using tcpdump on a Linux box located inside the ISP's internal network. Due to NDA requirements, we cannot disclose the name of the ISP, nor can we offer these traces for public download.

Each trace file is named using the following format: yyyymmdd-HHMMSS.tcpd.gz. The time and date refers to the local time when the capture was started. Both directions are contained within the single trace; however, the pcap format does not contain any information about a packet's direction so it is not possible to ascertain which direction a packet was travelling in the trace.

These traces were captured using a script that rotated the trace file after 20 million packets had been captured. When the file was rotated, the clock on the capture box was resynchronised. An interesting side-effect of this is that the end time of a trace and the start time of the next trace will overlap due to clock drift during the trace's capture. Because of the inaccurate timing, we can only assume that traces that overlap are contiguous but we cannot be 100% certain.

Timestamping within the traces themselves was taken using the system clock. As a result, the timing will be affected by clock drift and a lack of sub-microsecond accuracy, particularly considering that these traces were captured back in 1999. Timing accuracy that we take for granted now was not as readily available or widespread as when this traceset was captured.

The tcpdump snaplen for this traceset was set to 120 bytes, significantly smaller than that used in the previous traceset from this ISP. Obviously, there will be less layer 7 payload available in this traceset.

The recommended method for processing these traces is to use Libtrace, which we have developed. There are a number of tools included with libtrace such as a packet dumping utility, a trace format converter (for example, to convert to pcap), a trace splitting/filtering tool and a few statistic generators. We suggest you examine the Libtrace Wiki for more details on the Libtrace tools and the library itself.

Name Local Start Time Duration Total Packets Compressed Size
19991210-160905.tcpd Fri Dec 10 16:09:05 1999 45:05:31 20 million 887 MB
19991212-131342.tcpd Sun Dec 12 13:13:42 1999 43:09:04 20 million 883 MB
19991214-082158.tcpd Tue Dec 14 08:21:58 1999 38:11:43 20 million 917 MB
19991216-100023.tcpd Thu Dec 16 10:00:23 1999 28:51:26 15 million 682 MB