This MIB object is used to configure the QoS preconditions for the end point. The QoS precondition procedures are defined in RFC 3312. When using QoS preconditions procedures during session establishment, the E-DVA MUST assume that the local upstream and downstream QoS resources for the session are already allocated. When the E-DVA is configured as 'required' the E-DVA MUST establish media sessions using the QoS preconditions procedures. If the remote endpoint does not support QoS preconditions, the session establishment fails. Otherwise the communication is established using preconditions. When the E-DVA is configured as 'supported' the E-DVA MUST establish media sessions using the QoS preconditions procedures only when interworking with a remote endpoint that requires QoS preconditions to be used in order to complete session establishment. If the remote endpoint does not require the use of QoS preconditions (e.g., remote endpoint does not support QoS preconditions or indicates them as optional), then the E-DVA MUST establish the communication without using QoS preconditions. When the E-DVA is configured as 'disabled' the E-DVA MUST NOT use the QoS preconditions procedures during session establishment (i.e., acting as if QoS preconditions were not supported). If the remote endpoint requires the use of QoS preconditions, then session establishment fails. Below are the E-DVA application of the preconditions procedures. Precondition E-DVA Preconditions Other endpoint Call MIB Object strength-tag Preconditions Result value strength-tag =========================================================== 'required' mandatory mandatory P 'required' mandatory optional P 'required' mandatory none CF 'supported' optional mandatory P 'supported' optional optional NP 'supported' optional none NP 'disabled'* no strength-tag mandatory CF 'disabled'* no strength-tag optional NP 'disabled'* no strength-tag none NP (*) or E-DVA does not implement preconditions P Call is established with preconditions NP Call is established without preconditions CF Call Fails When the E-DVA does not support QoS preconditions, the E-DVA MUST reject SNMP SET operations for this MIB object indicating the SNMP error code 'wrongValue' in the SNMP SET response. When a SET operation is caused by the E-DVA configuration file, the E-DVA MUST ignore the SET operation, report 'passWithWarnings' error code, and register an attempt for SET operation in the ErrorOidTable.