User's Manual

Polycom® RealPresence Collaboration Server (RMX) 1500/2000/4000 Administrator’s Guide
H-36 Polycom, Inc.
• Setting an additional system flag may be required on the Collaboration Server when
running Video Switching conferences.
For more details, see "Collaboration Server Configuration for CAC Implementation” on
page H-64.
FEC Support
Microsoft RTV FEC (Forward Error Correction) is supported in the Collaboration Server to
control and correct packet loss when receiving and sending video streams using the
Microsoft Lync Server 2010 communications software. All RTV resolutions and options,
including B Frame, are supported.
Redundant video packets are sent over the network during video stream transmission.
When packet loss occurs, FEC is automatically activated and the redundant packet is used to
recover the lost packet.
When receiving video transmissions, packet loss automatically triggers FEC in the
Collaboration Server. When sending video transmissions, Collaboration Server sends FEC
packets when the RTCP RX report contains packet loss that is greater than or equal to 1
percent.
Media Over TCP
In previous Collaboration Server versions, media such as video, audio, content and FECC is
transmitted using the UDP transport protocol. In version 7.7, media is automatically
transmitted through TCP when UDP, the default transport protocol, is not available. Media
over TCP is supported using the Microsoft ICE environment.
The media transport protocol type (UDP/TCP) is displayed in the Participant Properties -
Channel Status - Advanced dialog box.
The media transport protocol type is displayed for the following IP addresses:
• Collaboration Server IP Address
• Participant IP Address
• ICE Collaboration Server IP Address - only when ICE is functional
• ICE Participant IP Address - only when ICE is functional
Network Error Recovery
When a short network error occurs, for example 5 seconds, Collaboration Server
automatically recovers, enabling calls in Microsoft Lync to continue the video or audio
conference without disconnecting. However, when a longer network error occurs, the call is
disconnected. The presence status mode is correctly updated from Busy to Available. There is
no configuration required for this procedure.
SIP Dialog Recovery
Collaboration Server has the ability to automatically recover from a SIP dialog failure, which
can occur in long duration calls in Meeting Rooms using the Microsoft Lync client. There is
no configuration required for this procedure.