HP A6600 Configuration Manual page 51

Table 3 Congestion management technology comparison
Number of
Type
queues
FIFO 1
PQ 4
CQ 16
WFQ Configurable
Advantages

No need to configure, easy to use

Easy to operate, low delay
Absolute bandwidth and delay
guarantees for real-time and mission
critical applications such as VoIP

Bandwidth assignment in percentages
for different applications

Bandwidth reassignment to increase
bandwidth for each class when
packets of certain classes are not
present

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
45
Disadvantages

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.

Need to configure; low processing
speed.

If no restriction is imposed on
bandwidth assigned to high-priority
packets, low-priority packets may
fail to get bandwidth.
Need to configure; low processing
speed.
The processing speed is faster than PQ
and CQ but slower than FIFO.