The SBC Core supports the following Real Time Control Protocol (RTCP) modes for media:
Table : RTCP Modes for Media
RTCP Relay for pass-through calls with RTCP enabled on both legs
RTCP is relayed between two end users. The SBC will not terminate the RTCP sessions; however, it will set up the media-path to forward RTCP packets from one party to the other. This is the default and recommended approach for handling RTCP for pass-through calls.
RTCP termination for a pass-through call with RTCP enabled on only one leg
If RTCP is enabled on only one leg of a pass-through call and "
terminationForPassThrough" flag is also enabled, the SBC generates RTCP for that leg.
RTCP for transcoded calls legs
If RTCP is enabled on the leg, the SBC will terminate RTCP.
In either pass-through or termination modes, the SBC collects packet RTCP statistics and reports them for output to CDRs. Configurable parameters include:
- Media peer inactivity—Configure media peer inactivity time out value. When using this feature, you must also set the flag,
peerAbsenceAction, from the Packet Service Profile.
- Media port range—Use this control to set the UDP media port range for RTP and RTCP.
- Media RTCP control—Configure sender report interval.
% set system media
inactivityTimeout <20-1260, in multiples of 10>
sendBYEPacket <disabled | enabled>
Use this control to specify (reserve) an amount, as a percentage, of bandwidth usage to limit across all physical interfaces for non-RTP media (default = 0).
This feature only applies to TCP media traffic such as MSRP.
Use this control to set detection of media peer inactivity (
inactivityTimeout) which can be used in conjunction with packet loss rate parameter (
packetLossThreshold) of Packet Service Profile.
inactivityTimeout – (range: 20-1260 / default = 60) Set RTP/RTCP inactivity timeout value (in seconds, in multiples of 10) to guard against loss of media connection. The timer is restarted whenever an RTP or RTCP packet is received from the peer.
When both RTP and RTCP are enabled, timeout will only occur if both packet types remain undetected for the configured
inactivityTimeout duration. If RTCP is not enabled, then only the absence of RTP causes the timer to expire. .
mediaPeerInactivity is enabled (configured with an
inactivityTimeout value), SBC detects media inactivity within the configured inactivity timeout value + X, and then executes the configured action (where the X is from 0 - 10 seconds).
Use this control to set the UDP media port range for RTP and RTCP.
baseUdpPort – Base UDP port number (inclusive) for RTP/RTCP media. (range: 1024-65534 / default = 1024).
maxUdpPort – Maximum UDP port number (inclusive) for RTP/RTCP media. (range: 1024-65534 / default = 65148).
Ensure that SIP Signaling Port
portNumber value is outside the configured
transportProtocolsAllowed = "
mediaPortRange is configured, user is prompted to continue with the configuration.
Use this control to configure the RTCP session.
sendBYEPacket – Use this flag to choose whether or not to send RTCP BYE packet.
disabled – Use this setting to suppress RTCP BYE packet in a pass-through scenario when RTCP
terminationForPassthrough option is enabled and the call is not established. This setting is useful to avoid one-way audio when Dynamic LRBT and RTCP are in use at the same time.
enabled – When this flag is enabled, the SBC sends the RTCP BYE packet when a call is terminated. This command affects all calls configured with RTCP termination.
enderReportInterval – Use this value as the initial interval (in seconds) for SBC to generate sender/receiver report when RTCP is terminated on the SBC. (range: 5-120 / default = 5).
This port range is used by the SBC to advertise its TCP port on which it can accept connections. A unique unused port from this range will be included in the SDP media line in the offer or answer towards the MSRP UAs. SBC uses a port from this range per MSRP call leg if it takes up a TCP server role.
To create a TCP port range, use the
maxServerPort to specify the minimum and maximum values as described below.
baseServerPort – Base port number (inclusive) for TCP media server (range: 1-65534 / default = 1024).
maxServerPort – Maximum port number (inclusive) for TCP media server (range: 1-65534 / default = 65534).
The following example sets
inactivityTimeout value to 90, the
baseUdpPort to 6000, the
maxUdpPort number to 65200 and the
senderReportInterval to 6 seconds and
sendBYEPacket to enabled, plus sets the
peerAbsenceAction parameter from
packetServiceProfile object to send a trap if inactivity is detected.
set system media mediaPeerInactivity inactivityTimeout 90
set system media mediaPortRange baseUdpPort 6000 maxUdpPort 65100
set system media mediaRtcpControl senderReportInterval 6
set system media mediaRtcpControl sendBYEPacket enabled
set profiles media packetServiceProfile DEFAULT peerAbsenceAction peerAbsenceTrap
show system media