Strict-Priority Queueing; Weighted Random Early Detection - Dell Force10 S4810P Configuration Manual

QoS Rate Adjustment is disabled by default, and no
Task
Include a specified number of bytes of packet overhead
to include in rate limiting, policing, and shaping
calculations. For example, to include the Preamble and
SFD, enter
qos-rate-adjust
overhead fields you must know the number of bytes you
want to include.

Strict-priority Queueing

You can assign strict-priority to one unicast queue, 1-7, using the command
CONFIGURATION mode. Strict-priority means that FTOS dequeues all packets from the assigned queue
before servicing any other queues.
• The
strict-priority
• A queue with strict-priority can starve other queues in the same port-pipe.
• On the E-Series, this configuration is applied to the queue on both ingress and egress.

Weighted Random Early Detection

Weighted Random Early Detection
Weighted Random Early Detection (WRED) congestion avoidance mechanism that drops packets to
prevent buffering resources from being consumed.
Traffic is a mixture of various kinds of packets. The rate at which some types of packets arrive might be
greater than others. In this case, the space on the BTM (ingress or egress) can be consumed by only one or
a few types of traffic, leaving no space for other types. A WRED profile can be applied to a policy-map so
that specified traffic can be prevented from consuming too much of the BTM resources.
WRED uses a profile to specify minimum and maximum threshold values. The minimum threshold is the
allotted buffer space for specified traffic, for example 1000KB on egress. If the 1000KB is consumed,
packets will be dropped randomly at an exponential rate until the maximum threshold is reached
(Figure 39-13); this is the "early detection" part of WRED. If the maximum threshold—2000KB, for
example—is reached, then all incoming packets are dropped until less than 2000KB of buffer space is
consumed by the specified traffic.
836
| Quality of Service (QoS)
8. For variable length
supersedes
bandwidth-percentage
is supported only on platform
is listed in the running-configuration.
qos-rate-adjust
Command Syntax
qos-rate-adjust overhead-bytes
Default: Disabled
C-Series and S-Series Range: 1-31
E-Series Range: 1-144
an
bandwidth-weight
e
Command Mode
CONFIGURATION
from
strict-priority
percentage configurations.