Set Up UDP Latency Control

For UDP applications and non-IP protocols such as IPX and AppleTalk, you can use a delay bound in a rate policy to provide flow control. Since UDP does not rely on acknowledgments to signal successful receipt of data, there is no concept of a flow-control window. Packets are transmitted one after another without regard to whether or not the recipient can handle them. However, "well-behaved" UDP applications communicate packet loss to the sender so that it can slow down.

PacketWise uses a UDP latency control mechanism to rate-control individual UDP traffic flows and minimize packet loss. PacketWise accumulates incoming UDP packets on a flow-by-flow basis when they are not scheduled for immediate transfer. With the UDP latency control mechanism, you define a delay bound — how long the packets can remain buffered before they become too old to be useful. If UDP flows don't get sent immediately (because of link congestion, for example), they are placed in a buffer or queue. UDP flows stay in the queue until they are sent or until the delay bound time is exceeded, in which case the packets are dropped.

Note: Unless you have specific requirements for buffering non-TCP traffic, it is recommended that you do not change the delay bound value, as it has been optimized for most network environments.

Note: To perform this task from PolicyCenter, you must first select a unit or draft configuration in the Configurations window. Then select the Class Tree tab from the right pane of this window.

To set latency control for a UDP class:

1. If you haven't done so already, create a rate policy for the UDP class.

2. Click delay bound in the Policy window.  show screen

3. Define the maximum length of time that PacketWise will retain UDP packets (1 to 10,000 milliseconds).

4. Click OK.

5. Click apply changes in the Policy window.