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Quantitative Finance · शब्दावली

Packet capture file, timestamp trailer क्या है?

अन्य नाम: packet capture file · timestamp trailer

Definition 5.2 Networks, Hardware and Trading Infrastructure · अध्याय 5 — Capturing and Monitoring the Network

A packet capture file stores a capture as a sequence of records, each a timestamp, a length and the frame’s bytes; the libpcap format and its successor pcapng are the common ones, with nanosecond timestamps in their newer variants. A timestamp trailer is a block of bytes that a tapping or switching device appends to the end of a copied frame, carrying the time at which the device saw the frame and where it saw it (device and port), so that the timestamp travels with the frame to wherever it is stored.

Watching a cage from outside. Taps on every handoff copy both directions; a timestamping device appends a trailer to each copy (time, device, port) against the grandmaster’s time and aggregates the copies; the capture appliance stores and analyses them. No program in the cage is involved.
Figure 5.1. Watching a cage from outside. Taps on every handoff copy both directions; a timestamping device appends a trailer to each copy (time, device, port) against the grandmaster’s time and aggregates the copies; the capture appliance stores and analyses them. No program in the cage is involved.
The timestamp trailer of firm.wirecap: the device and port that saw the frame and the full UTC time in seconds and nanoseconds, appended after the frame. Vendors’ trailers carry the same information in their own layouts.
Figure 5.2. The timestamp trailer of firm.wirecap: the device and port that saw the frame and the full UTC time in seconds and nanoseconds, appended after the frame. Vendors’ trailers carry the same information in their own layouts.
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