Configuring RTCP to Support Held Calls Using RR and RS Bandwidth Modifiers

Overview

This best practice provides guidance on configuring RTCP RR/RS Bandwidth modifiers from EMA to support held calls for a Multimedia Telephony Service for IMS (MTSI) environment as described on the page AMR and RTCP Enhancements.

SBC ERE Configuration

Configuring Packet Service Profile in ERE

Execute the following command to configure PSP:

set profiles media packetServiceProfile DEFAULT rtcpOptions rtcp enable

Enabling RTCP for HELD Calls

Execute the following command to configure the HELD calls:

set profiles media packetServiceProfile DEFAULT rtcpOptions rtcp enable enableRTCPForHeldCalls enable

Configuring RR and RS Bandwidth Values

Execute the following command to configure RR and RS bandwidth values:

set profiles media packetServiceProfile DEFAULT rtcpOptions rtcp enable enableRTCPForHeldCalls enable rrBandwidth 250 rsBandwidth 250

Configuring IP Signaling Profile

Execute the following command to send the RR and RS bandwidth information in the SDP offer:

set profiles signaling ipSignalingProfile DEFAULT_SIP commonIpAttributes flags sendRTCPBandwidthInfo enable

PSX Configuration

Configure Packet Service Profile on PSX

1. In the PSX Manager window, choose Packet Service Profile from the drop-down menu.
   Figure 1: PSX - Packet Service Profile

   
   

2. To create Packet Service Profile, right click on the Selection Area.
   Figure 2: Selection Area

   
   

    Select New from the resultant pop-up menu.

3. The Packet Service Profile window appears. Provide the Packet Service Profile name.
   Figure 3: Packet Service Profile

   
   

   
   Scroll down the display window to locate RTCP option.

   
   

4. Choose the RTCP option to enable it. This action enables the RTCP configurable flags.
   Figure 4: PSX RTCP - Fields

   
   

   
   The following parameters are displayed:

   All available parameters require RTCP to be enabled.

   Table 1: PSX RTCP - Fields parameters
   

   Parameter	Length/Range	Default	Description
   RTCP	NA	Disabled	When selected, this option enables Real-time Transport Control Protocol (RTCP) for the channel. RTCP is used to report traffic congestion data.
   Packet Loss Threshold (Packets Lost/100,000 Packets)	NA	0	The packet loss threshold, measured in number of packets lost per 100,000 packets.
   RR Bandwidth	100-4000	250	The RTCP bandwidth allocated to active data senders.
   RS Bandwidth	100-3000	250	The RTCP bandwidth allocated for receivers.
   Packet Loss Action	NA	None	The action to take when the packet loss threshold is exceeded on the channel. Possible actions are: None—No action. Trap—Generate an SNMP trap. Trap and Disconnect—Generate an SNMP trap and disconnect the call. Trap and Adapt—(applies to GSX only) Generate an SNMP trap and invoke an adaptation mechanism.
   Enable RTCP Only For HELD Calls	NA	Disabled	If this parameter is enabled, SBC ignores the configured RR/RS values in the Packet Service Profile and send RR/RS = 0 in the offer/answer and disables RTCP when the call is active. When the call is HELD, and a re-INVITE is sent,  the CPN (SBC) uses the configured values in the Packet Service Profile for RTCP bandwidth and enables RTCP. When the call is RESUMED, the CPN (SBC) again disables RTCP by sending RR/RS=0 in the re-INVITE. If disabled the older behavior of SBC is applicable.
   Termination For Pass-Through Calls	NA	NA	When enabled, RTCP is terminated and generated locally even for pass-through calls.

5. Make the desired changes to these parameters.

6. Click Save to save the configuration.

Configure IP Signaling Profile on PSX

1. In the PSX Manager window, choose IP Signaling Profile from the drop-down menu.
   Figure 5: PSX Codec - IP Signaling Profile

   
   

   
   

2. To create IP Signaling Profile, right click on the Selection Area.
   Figure 6: Selection Area

   
   

   
   A pop-up menu appears. Select New from the pop-up menu.
   
   

   
   

3. The IP Signaling Profile window appears. Provide the IP Signaling Profile name.
   Figure 7: IP Signaling Profile

   
   

   
   Scroll down the display window to locate Common IP Attributes - Communicating With The Peer Regardless Of Call Direction section.
   
   

   
   

4. Enable the "Send RTCP Bandwidth Info" flag identified in the screen capture below:
   Figure 8: PSX IP Signaling Profile - Fields

   
   

   
   The following flag is now enabled:
   Table 2: PSX IP Signaling Profile - Fields parameter

   Parameter	Length/Range	Default	Description
   Send RTCP Bandwidth Info	NA	NA	When this flag is enabled, the RR and RS bandwidth information, b=RR: and b=RS:, is sent in the SDP offer.

5. Click Save to save your changes.

Multiple Audio Streams Support and Send RTCP Bandwidth Info Flag Behavior

When the sendRTCPBandwidthInfo and the multipleAudioStreamsSupport flags are enabled, observe the following behaviors:

• The SBC sends the RR/RS attributes toward the Egress only if the RR/RS attributes are received in the SDP.
• The SBC does not send the RR/RS attributes towards the Egress if the RR/RS attributes are not received in the SDP.

The following behaviors are expected when the configuration is enabled:

Case 1:

Case 2: