Справочник Пользователя для Polycom 1800

RealPresence Collaboration Server (RMX) 1500/1800/2000/4000 Administrator’s Guide 

Polycom®, Inc. 

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● Content – frozen images, blurring, distortion, slow screen refresh rate

The Lost Packet Recovery (LPR) algorithm uses Forward Error Correction (FEC) to create additional 
packets that contain recovery information. These additional packets are used to reconstruct packets that are 
lost, for whatever reason, during transmission. Dynamic Bandwidth Allocation (DBA) is used to allocate the 
bandwidth needed to transmit the additional packets.

● If packet loss is detected in the packet transmissions of either the video or Content streams:



LPR is applied to both the video and Content streams.



DBA allocates bandwidth from the video stream for the insertion of additional packets containing 

recovery information.

● LPR is supported in H.323 and SIP networking environments only.
● In LPR-enabled Continuous Presence conferences:



Both LPR-enabled and non-LPR-enabled endpoints are supported. 



The LPR process is not applied to packet transmissions from non-LPR-enabled IP (H.323 and 

SIP) and ISDN (Collaboration Server 1500/2000/4000) endpoints.



Non-LPR-enabled endpoints can be moved to LPR-enabled conferences.



LPR-enabled endpoints cannot be moved to non-LPR-enabled conferences.

● In LPR-enabled Video Switched conferences (Collaboration Server 1500/2000/4000):



H.323 and SIP endpoints are supported.



When cascading between conferences running on Collaboration Server and MGC (Polycom 

legacy MCU), LPR is not supported over the link between the two conferences.



Non-H.323 participants cannot be created, added or moved to LPR-enabled Video Switched 

conferences.

● When connecting via an Entry Queue:



A participant using an LPR-enabled endpoint can be moved to a non-LPR-enabled conference. 

The participant is connected with LPR enabled.



SIP and ISDN/PSTN (Collaboration Server 1500/2000/4000) participants cannot be moved to 

LPR-enabled Video Switched conferences.

LPR is enabled or disabled in the Conference Profile dialog box.

● CP Conferences – LPR is enabled by default in the New Profile – Advanced dialog box.
● VSW Conferences – If Video Switching is selected, the LPR check box is automatically cleared and 

LPR is disabled. LPR can be enabled for VSW conferences but H.320 and SIP participants will not 

be able to connect.
For more information, see