3.3.5.3 Receiving a Bandwidth Admission Control Update Request Message

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If the Allocate Request message contains a Bandwidth Admission Control Message attribute with a value of "Reservation Update", the request is processed as follows:

  • The request MUST include a Bandwidth Reservation Identifier attribute, as specified in section 2.2.2. If the Reservation ID value does not match an active bandwidth reservation, the server MUST continue to process the Allocate Request message as specified in [MS-TURN] section 3.3.5.1 and ignore the Bandwidth Admission Control Message action.

  • The request SHOULD include a Bandwidth Reservation Amount attribute, as specified in section 2.2.3.

  • The request SHOULD include the SIP Dialog Identifier attribute, as specified in section 2.2.12.

If all of the required attributes are present and valid, the server MUST restart the Bandwidth Reservation Lifetime timer.

If the Bandwidth Reservation Amount attribute is present, the server MUST check the bandwidth values against the bandwidth values that were previously committed for this reservation. If the values are lower than the committed values, the server SHOULD update the reservation, returning unused bandwidth back to the bandwidth policies of the network paths involved in the reservation. If the values are higher than the committed values, the server MUST re-check the network paths involved in the reservation for the availability of additional bandwidth. If bandwidth is available, the server SHOULD reserve additional bandwidth for the reservation.

Once the server has finished restarting the timer and updating the bandwidth reservation, it responds with an Allocate Response message specified as follows:

  • The response MUST be formed as specified in [MS-TURN] section 3.3.5.1.

  • The response MUST include a Bandwidth Admission Control Message attribute with a value of "Reservation Update", as specified in section 2.2.1.

  • The response MUST include a Bandwidth Reservation Identifier attribute, as specified in section 2.2.2.

  • The response SHOULD include a Bandwidth Reservation Amount attribute, as specified in section 2.2.3.