R3303-HP HSR6800 Routers ACL and QoS Configuration Guide

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Table 4 Congestion management technique comparison
T
yp
e Number of
q
ueues Advanta
g
es Disadvanta
g
es
FIFO 1
• No need to configure, easy
to use.
• Easy to operate, low delay.
• All packets are treated equally.
The available bandwidth, delay
and drop probability are
determined by the arrival order of
packets.
• No restriction on traffic from
connectionless protocols
(protocols without any flow control
mechanism, UDP, for example),
resulting in bandwidth loss for
traffic of connection-oriented
protocols (TCP, for example).
• No delay guarantee for
time-sensitive real-time
applications, such as VoIP.
PQ 4
Absolute bandwidth and delay
guarantees for real-time and
mission-critical applications,
such as VoIP.
• Need to configure, low
processing speed.
• If no restriction is imposed on
bandwidth assigned to
high-priority packets, low-priority
packets might fail to get
bandwidth.
CQ 16
• Bandwidth assignment in
percentages for different
applications.
• Bandwidth reassignment to
increase bandwidth for each
class when packets of certain
classes are not present.
Need to configure, low processing
speed.
WFQ Configurable
• Easy to configure.
• Bandwidth guarantee for
packets from cooperative
(interactive) sources (such as
TCP packets).
• Reduced jitter.
• Reduced delay for interactive
applications with a small
amount of data.
• Bandwidth assignment
based on traffic priority.
• Automatic bandwidth
reassignment to increase
bandwidth for each class
when the number of traffic
classes decreases.
The processing speed is faster than
PQ and CQ but slower than FIFO.