Enhanced Red Support - Extreme Networks PoS Installation And User Manual

Configuring QoS Functions
config diffserv replacement priority <vpri> code_point <code_point>
ports [<portlist> | all]
By doing so, the hardware queue used to transmit a packet determines the DiffServ
value replaced in the IP packet.
To verify the DiffServ configuration, use the command:
show ports <portlist> info detail

Enhanced RED Support

Random Early Detection (RED) is a congestion avoidance mechanism. The basic idea
behind RED is that most data transports detect packet loss and will, therefore, restrain
transmission—if only temporarily—when they detect dropped packets. Consequently, if
the switch needs to signal another device to slow transmission due to congestion, RED
provides a way of intelligently dropping packets.
This section describes the changes and additions to ExtremeWare to support RED in
conjunction with PoS modules that have IP frames encapsulated in BCP or IPCP, not
MPLSCP. The Extreme implementation of RED combines the functions of the RED
algorithm with IP precedence to provide support for preferential traffic handling for
higher-priority packets. This implementation provides weighted RED (WRED)
functionality through two packet-drop probabilities (described below), so that a device
can selectively drop lower-priority traffic when an interface begins to show signs of
congestion. This capability is combined with DiffServ attributes to allow you to tailor
performance characteristics for different classes of service.
Configuring RED Drop Probability
To configure the RED drop probability for a specified PoS port, use the following
command:
config red [drop-probability | low-drop-probability | high-drop-probability]
<percent> {ports <portlist>}
The optional , , and keywords
low-drop-probability high-drop-probability ports
are supported only for SONET ports.
If you omit the keyword, the command applies the setting to all ports.
ports
Packet Over SONET Module Installation and User Guide 3-51