Ethereal/Wireshark Analysis

Voice only analysis

The following screenshot shows network-traffic (in Bytes/s) for the following connections:

• Black: traffic from and to Trixbox #1
• Red: traffic between the 2 Windows machines running X-lite
• Green: traffic between laptop #1 and its Asterisk
• Blue: traffic between the two Asterisk PBX's
• Pink: traffic between Windows machine #1 and its Asterisk

From the graph shown above there can be concluded that indeed the two X-Lite machines are only connected to their own Trixbox, i.e. there is no direct traffic between the two X-Lite machines.

Voice and video analysis

Schematic sketch of the situation:

In the screenshot below, the following events were measured:

• @4 sec: Video was turned on
• @14 sec: Video was set to black (connection lost with DVdriver)
• @20 sec: Video showed moving pictures again.

Legenda:

• Black: traffic from and to Trixbox #1
• Red: traffic between the 2 Windows machines running X-lite
• Green: traffic between laptop #1 and its Asterisk
• Blue: traffic between the two Asterisk PBX's
• Pink: traffic between Windows machine #1 and its Asterisk

The following graph shows the traffic is almost constant. Till 35sec the conversation included audio and video. The rest is audio-only.

This measurement shows there is no traffic between both SIP-phones, only via (both) Asterisk PBX.

Differences between voice and video

For this test, we connected 2 SIP phones to the same Asterisk PBX. We meassured the bandwitdh used between the following 3 points:

1. SIP-phone #1 with camera
2. SIP-phone #2 without camera
3. Asterisk PBX

Legenda:

• Black shows audio & video from SIP-phone #1 to the PBX (video starting at the 10^th second)
• Blue shows audio-only from SIP-phone #2 to the PBX
• Pink shows all traffic between SIP-phone #1 and the PBX (both directions)