3Com S330 manual Configuring Ports, Setting Congestion Thresholds

88CHAPTER 4: CONFIGURING PATHBUILDER S330/S310 MODULES, PORTS, AND APPLICATIONS

When you select one of these options, a prompt appears at the bottom of the screen, allowing you to enter a new threshold in the range 0% to 100%. When the buffer reaches the Congestion On threshold, the congestion filter is on. When the buffer falls below the Congestion Off threshold, the congestion filter is off.

For example, if you set Congestion On to 75% and Congestion Off to 50%, the congestion filter is on when the buffer is 75% full and is off when the buffer drops below 50% full.

See “Setting Congestion Thresholds” below for further details about congestion thresholds.

CAUTION: You should enable early packet discard for AAL5 traffic only.

8Select [4] Previous Menu to return to the CTX Buffers menu.

9Press [Esc] to return to the CTX menu.

10Select [3] Apply CTX Buffer Changes to apply your settings.

CAUTION: This operation will affect traffic.

	Setting Congestion Thresholds
	For every connection where early packet discard is enabled, a status is kept when
	there is a partial packet for that connection in the queue. Once the queue cell level
	exceeds the Congestion On thresholds, only connections with partial packets
	already existing in the queue are allowed in. Cells from other connections are
	dropped. Once the congestion has subsided to the Congestion Off level, then all
	remaining connections are allowed.
	Set the Congestion On threshold based on the maximum packet size expected and
	the number of active connections sending packets at a particular instant based on
	a probability model.
	Set the Congestion On level to allow some hysteresis in the operation.
Configuring Ports	The PathBuilder S330/S310 ports each have an administrative and an operational
	status. To set up a virtual circuit, you must first set the administrative status of the
	port which will carry the circuit online to In Service. You can also configure other
	parameters, depending on the type of port.
	When you set the administrative status to Out of Service, the operational status is
	set to Out of Service whether or not the port is actually operational or not. Once
	you set the administrative status to In Service (online), the operational status will
	indicate the true port status (Out of Service if there is a port failure, or In Service if
	not).
	The following sections tell you how to configure specific ports on the PathBuilder
	S330/S310.