Polycom MGC Administrator, Руководство администратора

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MGC Administrator’s Guide
3-63
b. Define the following fields:
Table 3-17: QoS of Ethernet Service Dialog Box Options
Field Description
Enable Select the Enable check box to implement QoS for
marking outgoing IP packets, either according to the
DiffServ standard or the IP Precedence mechanism.
If the
Enable check box is cleared, QoS is not
implemented.
DiffServ and
Precedence DiffServ and Precedence are two methods for
encoding the packet’s priority. The priority set here
for audio and video packets should match the priority
set in the router.
•
Select DiffServ when the network router uses
DiffServ for priority encoding. When the MCU
implements DiffServ, it prioritizes the IP packets
according to the
QOS PARAMS section flags, set
in the system configuration (system.cfg) file. (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.
Note : 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.