Polycom MGC-100 Getting Started Manual page 61

Table 3-9: QoS of Ethernet Service Dialog Box Options (Continued)
Field
DiffServ and
Precedence
Audio and Video
TOS
Chapter 3 - Initial System Configuration
Description
DiffServ and Precedence are two methods for
encoding the packet's priority.
If you are not sure which QoS policy your router
supports, select Precedence combined with None in
the TOS field. Precedence is the default mode as it
is capable of providing priority services to all types of
routers, as well as being currently the most common
mechanism.
•
Select DiffServ when the network router uses
DiffServ for priority encoding (The default priority
is 4 for audio and video packets).
Note: If you select DiffServ but your router does
not support this standard, IP packets queue on
the same communication links with data packets.
This non-prioritized queueing greatly increases
the latency and jitter in their delivery.
•
Select Precedence when the network router
uses Precedence for priority encoding, or when
you are not sure which method is used by the
router.
You can prioritize audio and video IP packets to
ensure that all participants in the conference hear
and see each other clearly.
Select the desired priority, where 0 is the lowest
priority and 5 is the highest.
The recommended priority for both audio and video
is 4 to ensure that the delay for both packets is the
same and audio and the video packets are
synchronized. Selecting 5 for video and 4 for video
will result in lip sync.
Type of Service (TOS) defines optimization tagging
for routing the conferences audio and video packets.
• Delay – The recommended default for video
conferencing.
•
None – No optimization definition is applied.
Select None if you do not know which standard your
router supports.
3-31