Application Performance Engineering Blog – Shunra Software

Packet Loss:

• When networks get congested over a long period of time the router buffers get saturated which at some point leads to a situation where there is no room to store more pakets in the buffers, so new arriving packets get dropped
• Some routers implement a mechanism called random early detection, since IP doesn’t provide any explicit way to indicate that the network is congested, routers use loss for that purpose. Such loss is a way of communicating back to the users the need to scale back the offered load on the network. RED is becoming less common as new QoS techniques are used to implement rate control.
• Communications across wireless and cellular networks may encounter packet loss due to interference or a weak signal
• Hardware and cable errors are a common cause of packet loss

From the network perspective, loss can be categorized as random loss or loss due to congestion. The average packet loss rate for a network connection gives an overall sense of the quality of the connection. A connection with less than 1 percent average packet loss is considered a decent connection. But average loss doesn’t tell the whole story. There is importance to the type, or pattern, of packet loss. There are at least two kinds of packet loss that should be considered: ‘Random’ loss and ‘Burst’ loss. To explain the difference between them, let’s suppose we are trying to run 2 Voice over IP conversation over 2 links that have an average of 1 percent packet loss. Call A loses one packet in every 100 packets over the entire call (random loss) while Call B loses 100 packets in two incidents – at the beginning and the end of the call (burst loss). Which call would you rather have? That’s why it is important to consider not just the average packet loss but also the type of loss and information on any bursts of packet loss over time.