RealPresence Collaboration Server (RMX) 1500/1800/2000/4000 Administrator’s Guide
Polycom®, Inc. 834
Enabling Precedence
Precedence is disabled by default. It is enabled by using the Setup > Precedence Settings menu to
display the Precedence Settings dialog box. Precedence is enabled by selecting the Use Precedence
check box.
See Configuring and Modifying Precedence Domains and DSCP Values .
When Precedence is enabled, all other QoS system settings are overridden by the parameters sent in the
SIP Message. For more information about QoS, see the RealPresence Collaboration Server (RMX)
1500/1800/2000/4000 Administrator’s Guide Modifying the Default IP Network Service .
SIP Message
A SIP Message is a request or a response between network entities that communicate using the SIP
protocol. The SIP Message header contains Precedence and Resource Priority (r-value) information and
an optional Require tag for each call.
For a full description of SIP Messages see IETF RFC 3261.
For a full description of Resource Priority (DSCP) see IETF RFC 2474.
For a full description of SIP r-priority see IETF RFC 4412.

Dial-in calls

If the Use Precedence check box in Precedence Settings is selected:
The RMX uses the information in the SIP Message header to match the call to a Precedence
Domain and a Precedence Level. Table5-45 summarizes of the default values.
Precedence Domain and Resource Priority - DSCP Default Values
Resource
Priority Precedence Level
DSCP Value
Audio Video
9 FLASH-OVERRIDE-OVERRIDE 33 (0x21) 33 (0x21)