3Com MSR 50 Series, Руководство по настройке

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1654 C
HAPTER
86: C
ONGESTION
M
ANAGEMENT
delay and jitter and ensuring the quality of audio or video service which is sensitive
to delay.
Figure 468 RTP queuing diagram
As shown in the above figure, an RTP packet is sent into a high priority queue. RTP
packet is the UDP packet whose port number is even. The range of the port
number is configurable. RTP priority queue can be used along with any queue
(e.g., FIFO, PQ, CQ, WFQ and CBQ), while it has the highest priority. Since LLQ of
CBQ can also be used to solve real-time service, it is recommended not to use RTP
together with CBQ.
Comparison of
Congestion
Management
Technologies
The above-mentioned congestion management technologies are available on the
device. Breaking through the single congestion management policy of FIFO for
traditional IP equipment, they provide strong QoS ability, which meets the
demands of different service quality required by different applications. For efficient
use of congestion management technologies, the following table compares the
available queuing technologies.
Congestion management technologies
Type Queue No. Advantages Disadvantages
FIFO 1
■
No need for
configuration, easy to
use
■
Easy operation, low
delay
■
All packets are treated
equally. The available
bandwidth, delay and drop
probability are decided by the
arrival order of the packets.
■
No restriction on the
unmatched data sources (that
is, flows without flow control
mechanism, UDP for
example), resulting bandwidth
loss of matched data sources
such as TCP.
■
No guarantee to the delay of
time-sensitive real-time
application, such as VoIP.