RTP and RTCP Bandwidth Calculation and Reporting
The Oracle Communications Session Border Controller supports changing bandwidth requirements in an ad-hoc mult-party conference by tracking reduced bandwidth needs as parties are placed on hold during the initiation of a multi-party call. The combination of the 5 AVPs are considered by network elements for this functionality.
This section is applicable to the Oracle Communications Session Border Controller's Rx implementation when acting as a P-CSCF and connecting with a PCRF. The 5 AVPs considered in this section are created and sent in AAR messages.
Max-Requested-Bandwidth-UL & Max-Requested-Bandwidth-DL AVPs
These AVPs reflect RTP bandwidth requirements for a call. The default behavior (i.e., no options are configured) that dictates how these AVPs are created follows.
The average rate limit scenario is when no b=AS: parameter in the SDP and the media-profile, average-rate-limit parameter is configured to a value greater than 0. The Oracle Communications Session Border Controller inserts the media-profile, average-rate-limit parameter ×8 into both Max-Requested-Bandwidth-UL & Max-Requested-Bandwidth-DL AVPs.
The SDP bandwidth scenario is when there is a b=AS: parameter in the SDP and the media-profile configuration element has the following configurations:
- average-rate-limit = 0
- sdp-rate-limit-headroom > 0
- sdp-bandwidth = ENABLED
When these conditions are met, the Max-Requested-Bandwidth-UL & Max-Requested-Bandwidth-DL AVPs are populated with the value in the b=AS: parameter + sdp-rate-limit-headroom ACLI parameter.
Optional AVP Creation
When the get-bw-from-sdp option is configured in the sip-config, the following occurs:
When SDP contains the
b=AS:parameter with valid value, the Oracle Communications Session Border Controller multiplies that value ×1000 and inserts the result in the Max-Requested-Bandwidth-UL and Max-Requested-Bandwidth-DL AVPs in an AAR message.
If there is no b=AS: line in the SDP, the value is taken from the media-profile, average-rate-limit parameter multiplied ×8 to get a bps value then inserted into the Max-Requested-Bandwidth-UL and Max-Requested-Bandwidth-DL AVPs in an AAR message.
The Oracle Communications Session Border Controller uses the b=AS: line (or chosen codec via the media-profile) from the final answer SDP for the session as the value for creation of these two AVPs.
RR-Bandwidth & RS-Bandwidth AVPs
These AVPs reflect RTCP bandwidth requirements for a call. When SDP contains:
b=RR:
b=RS:parameters and values, the Oracle Communications Session Border Controller inserts the values (after the :) into the respective RR-Bandwidth (521) and RS-Bandwith (522) AVPs. When these parameters are not present in the SDP, the RR-Bandwidth and RS-Bandwidth AVPs are not created in AAR messages sent to the PCRF. The sip-config, get-bw-from-sdp option must be configured to enable creation of these AVPs.
Flow-status AVP
The Flow-status AVP (511) is based on SDP direction. Tests for SDP are performed in the following order:
| SDP State | Flow-Status AVP (511) Set to |
|---|---|
| port in the SDP m-line is 0 | REMOVED (4) |
| Transport in m-line is "TCP" or " TCP/MSRP" | ENABLED (2) |
| a=recvonly and <SDP direction> = UE originated | ENABLED-DOWNLINK (1) |
| a=recvonly and <SDP direction> = UE terminated | ENABLED-UPLINK (0) |
| a=sendonly and <SDP direction> = UE originated | ENABLED-UPLINK (0) |
| a=sendonly and <SDP direction> = UE terminated | ENABLED-DOWNLINK (1) |
| a=inactive | DISABLED (3) |
| a=sendrecv or no direction attribute | ENABLED (2) |
UE originated - Call originator creates the SDP being considered.
UE terminated - Call terminator creates the SDP being considered.
Flow-status AVP is always created according and requires no configuration.