Extreme Networks ExtremeWare 7.5, Command Reference Manual

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2142 ExtremeWare 7.5 Command Reference Guide
PoS Commands—BlackDiamond Switch Only
configure red
configure red [drop-probability | low-drop-probability |
high-drop-probability] <percent> {ports <portlist>}
Description
Configures the RED drop probability for a specified port.
Syntax Description
Default
For PoS ports, both the low and high drop-probabilities default to 10%.
Usage Guidelines
The optional
low-drop-probability
,
high-drop-probability
, and
ports
keywords have been added
to support the PoS module. Currently, these new keywords are only supported for SONET ports.
Omission of the
ports
keyword indicates that the setting is to be applied to all ports.
The drop probability is specified as a percentage, where the
percent
parameter is an integer in the
range [1–100]. The implementation provides weighted RED (WRED) functionality via support for two
different drop probabilities: a
low-drop-probability
and a
high-drop-probability
. The DSCPs of IP
packets indicate whether the packet should be dropped with low probability or high probability, and
the appropriate percentage is then applied if WRED is active. WRED is only applied to IP packets, and
the
configure diffserv examination code-point
command supports complete flexibility in
assigning DSCPs to the two different drop-probability levels. The configured mapping of DSCPs to
drop-probability levels is used by WRED even if
diffserv examination
is disabled on the port.
The
drop-probability
keyword indicates that the specified percentage should be used for both the
low and high drop-probabilities, which effectively disables WRED and reverts to standard RED
operation. RED is active when the average queue length is between the minimum and maximum
thresholds. In this region, the probability that a given packet is dropped increases linearly up to the
configured drop probability at the maximum threshold. All packets are dropped when the average
queue length exceeds the maximum threshold.
Example
The following command configure a RED high drop-probability of 20% on the SONET ports:
config red high-drop-probability 20 ports 2:1-2:2
drop-probability Specifies both the high and low drop probability rates.
low-drop-probability Sets the low drop probability rate.
high-drop-probability Sets the high drop probability rate.
percent Specifies the percentage for the drop probability.
portlist Specifies the port number(s).