Packet Loss... A Sign of Trouble for Videoconferencing

The default LifeSize dialing speed is "auto" where the system will attempt to make a call just over 1 mbps. If there is significant packet loss at 1 mbps the LifeSize codec is smart enough to asymmetrically throttle down until packet loss is minimized, the result will be lower resolution but a stable call (a great selling feature BTW).

NOTE: It could take a few minutes for the call to settle down, so hit the blue button and keep an eye on packet loss (a snapshot) and not cumulative (the entire call). Also, consider making future calls at this adjusted speed.

Here are a few things to check if packet loss persists:

1. Ample Bandwidth - Plain and simple the site might not have ample bandwidth (contrary to the network admin's claims) If your laptop is on the same network a speed test of upload and download can be performed at sites such as this: http://speedtest.net

2. PING with Advanced Options - This is a basic networking test that can give you a good idea on what kind of quality is between two network points for a videoconferencing call . Also network problems can be identified and isolated with this simple tool. Open a command prompt window on a PC and enter the following command with an IP address of the remote location C:\>Ping <IP Address> -t -f -l 1024 (Note : Ctrl-C  will stop the ping) 

     t = Time (Pings the address until stopped)
     f = Fragment (Sets don’t fragment flag in packets)
     l = Length (Sets the size of the packet to simulate videoconferencing)

  4 A variance of more than 20% is not good – video will be watery, audio will warble
  4A spike of 100% is very bad – Audio could be lost video will freeze
  4Request timed out is a sign of a problem – It’s like going through bad cell phone coverage
  4Consistent times under 100 are very good, under 150 are good and under 200 are just ok
     - Run the test during different times of the day and days of the week
     - Run the test before, then during a conference call. If the times start to become inconsistent and jump
      around or time out, reduce the call connection speed. Try increasing the call connection to see when
      the network connection floods and times become inconsistent and jump around or time out

3. A Bad Network Cable - How many times has the network cable of that demo system been connected, disconnected and coiled up? It is a standard Ethernet cable so swapping it out is easy.

4. Duplex Mismatch - The default setting of the Lifesize network card is auto, if the switch that you are connecting to is set for anything other than auto it will create a mismatch that will cause packet loss every time. There are also instances where even if the switch and codec are set to auto they will not agree on a common setting. Ask the network admin to set the switch port to 100 mbps and full duplex and do the same to the Lifesize system under administrator preferences - network - general -network speed.

5. Packet Size Too Large For The Network To Handle - This is typically encountered when calling across the customer's private network, not out to the public internet. Certain network technologies such as MPLS add information to the video packets, the result is a packet size that certain network devices may not be able to handle properly. You can decrease the size of the packets leaving the codec to compensate user administrator preferences - video - video quality - video MTU. Start with 1300 but you may need to experiment.

6. QOS Setting - This is typically encountered when calling across the customer's private network, not out to the public Internet. There is a default QOS setting on the LifeSize codec that may not match the network you are on. Ask the network admin to provide the QOS method (diff serv or IP precedence) and values and populate the menu at: admin preferences - network - QOS - network QOS and values. If you are not sure or can't obtain the values try setting the QOS setting to none.

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