Stream Statistics

The Port Statistics Window displays interface or port level statistics and may include packets sent by other applications or the OS itself. This makes it difficult to compare whether received packet/byte count is same as sent count. Also there may be cases where you may be sending multiple streams and you would like to compare tx/rx counts for each stream.

For such cases, you can use Stream Statistics.

Stream names are available starting version 2.1

Configure Stream stats Tracking

1. Enable Stream Statistics tracking on both Tx and Rx ports - you can have multiple Tx/Rx ports
   
2. For all streams that you wish to track statistics for -
   1. Include the Special|Signature protocol on the Protocol Selection tab
   2. Configure a unique value as the Stream GUID (GUID stands for globally unique Id) in Protocol Data tab

Best Practice

For clear stream statistics and reports, use a unique GUID per stream and assign a descriptive stream name. Sharing a GUID across multiple streams or varying GUIDs via variables is supported, but makes stream-level identification and reporting harder

Run the test

1. Select Both Tx and Rx port(s)
2. Click on the Clear selected port stats button
3. Click on the Start Tx button
4. Click on the Stop Tx button

Fetch Stream Stats

1. Ensure Transmit is finished i.e. Transmit State is Off
2. Select all the Tx/Rx ports for which you wish to fetch and view stream statistics
3. Click on the Fetch selected port stream stats button
4. The stream statistics will open in a new tab in the Statistics Window
5. Expand the GUID row to see port-level details

Stream stats are available only for the last Tx run and cannot be aggregated across multiple Tx runs.

How does it work

The signature protocol is added to the end of the Ethernet frame just before the FCS. The last 4 bytes are a magic value indicating that the frame includes a special signature containing the Stream GUID. The transmitted frames will contain this special signature.

The duration is the largest Tx duration across all ports for the GUID; both Tx and Rx rates are calculated based on this duration value

Latency/Jitter is measured approximately every 5 seconds.

Limitations and Performance Impact

• Tx Stream Statistics is counted only after transmit is finished. Fetching stats before transmit is finished will return 0 values (v2.1 removes this limitation; fetching stats after transmit completes is still recommended)
• ICMP streams cannot be tracked
• The TX and RX ports should be on the same host and drone agent for latency/jitter measurement. The packet timestamps used for latency/jitter calculation are software timestamps provided by the OS and may not be precise (see man pcap-tstamp)