2.2.11.11 RTCP Profile Specific Extension for Network Congestion Notification

The format of the RTCP profile-specific extension for Network Congestion Notification is as follows<33>:

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
Type																Length
NTP Timestamp Integer
NTP Timestamp Fraction
Congestion Info								Reserved

Type (2 bytes): The extension type. Set to 0x000D (13).

Length (2 bytes): The extension length in bytes, including this header. Set to 0x0010(16).

NTP Timestamp Integer (4 bytes): The NTP timestamp integer part. The full resolution NTP timestamp is a 64-bit unsigned fix-pointer number. This field has the integer part of the NTP timestamp.

NTP Timestamp Fraction (4 bytes): The NTP timestamp fraction part.

Congestion Info (1 byte): The bitmask of congestion state,

            Bit 0: Uncongested according to relative one way delay;

            Bit 1: Congested according to relative one way delay;

            Bit 2: Uncongested according to packet loss rate;

            Bit 3: Congested according to packet loss rate;

            Bit 4-7: Reserved, The sender SHOULD set it to 0. The receiver MUST ignore it.

Reserved (3 bytes): Reserved. The sender SHOULD set it to 0. The receiver MUST ignore it.