1. Configuration Guide
  2. IMS Support
  3. RTP and RTCP Bandwidth Calculation and Reporting
  4. Flow-status AVP

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.

The P-Early-Media Header and the Rx Interface

As defined in 3GPP TS 24.229, IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 both the P-CSCF and IBCF may add, remove, or modify, the P-Early-Media header field within forwarded SIP requests and responses according to procedures in RFC 5009.

The P-CSCF can use the P-Early-Media header field for the gate control procedures, as described in 3GPP TS 29.214. In the current implementation, if you set the configuration option early-media-allow to none, the SBC sends the Flow-Status AVP (511) in any AAR request set to disable until there is a final response.

Although you can configure the SBC to provide PEM header information within the Flow-Status AVP (511) to provide early media status over the Rx interface, there are two conditions that must be in place before it can populate this AVP with PEM header flags.

The SBC does not include PEM header feature status in the Rx Flow-Status AVP unless:

  1. You enable the get-flow-status-from-sdp option in the sip-config.
    ORACLEACMEPACKET#(media-manager) options +get-flow-status-from-sdp
  2. There has been an SDP exchange. Note that provisional responses without SDP, which occur prior any SDP exchange, do not generate update data within the Rx flow-status AVP even if they include PEM status.