Diameter Latency determination

The purpose of latency determination is to estimate how much time takes for a message to be processed by a Diameter application.

The xml_tcp module computes average application processing latency by handling timestamps from messages exchanged on that connection.

• Each message sent by the module can be timestamped with the server's current time
• Application copies the timestamp from the received XML to the one it responds with
• If the module receives a timestamp it will compute the difference from the current time and adjust average latency

The timestamps need to be enabled in the xml_tcp.conf module. This can be done per Diameter listener

   [listener s6a]
   type=diameter
   ...
   add-timestamp=yes

If enabled the timestamps are added in their own XML element named timestamp-send:

   <m>
       <timestamp-send>1377071763411706</timestamp-send>
       ...
   </m>

The application is supposed to copy the received timestamp to the response in a timestamp-recv element:

   <m>
       <timestamp-recv>1377071763411706</timestamp-recv>
       ...
   </m>

These are exposed through the status of the xml_tcp module.