4.6. Statistics Summary Report Block

This block reports statistics beyond the information carried in the standard RTCP packet format, but is not as finely grained as that carried in the report blocks previously described. Information is recorded about lost packets, duplicate packets, jitter measurements, and TTL or Hop Limit values. Such information can be useful for network management.

The report block contents are dependent upon a series of flag bits carried in the first part of the header. Not all parameters need to be reported in each block. Flags indicate which are and which are not reported. The fields corresponding to unreported parameters MUST be present, but are set to zero. The receiver MUST ignore any Statistics Summary Report Block with a non-zero value in any field flagged as unreported.

The Statistics Summary Report Block has the following format:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     BT=6      |L|D|J|ToH|rsvd.|       block length = 9        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        SSRC of source                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          begin_seq            |             end_seq           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        lost_packets                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        dup_packets                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         min_jitter                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         max_jitter                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         mean_jitter                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         dev_jitter                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| min_ttl_or_hl | max_ttl_or_hl |mean_ttl_or_hl | dev_ttl_or_hl |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

block type (BT): 8 bits A Statistics Summary Report Block is identified by the constant 6.

loss report flag (L): 1 bit Bit set to 1 if the lost_packets field contains a report, 0 otherwise.

duplicate report flag (D): 1 bit Bit set to 1 if the dup_packets field contains a report, 0 otherwise.

jitter flag (J): 1 bit Bit set to 1 if the min_jitter, max_jitter, mean_jitter, and dev_jitter fields all contain reports, 0 if none of them do.

TTL or Hop Limit flag (ToH): 2 bits This field is set to 0 if none of the fields min_ttl_or_hl, max_ttl_or_hl, mean_ttl_or_hl, or dev_ttl_or_hl contain reports. If the field is non-zero, then all of these fields contain reports. The value 1 signifies that they report on IPv4 TTL values. The value 2 signifies that they report on IPv6 Hop Limit values. The value 3 is undefined and MUST NOT be used.

rsvd.: 3 bits This field is reserved for future definition. In the absence of such a definition, the bits in this field MUST be set to zero and MUST be ignored by the receiver.

block length: 16 bits The constant 9, in accordance with the definition of this field in Section 3.

SSRC of source: 32 bits As defined in Section 4.1.

begin_seq: 16 bits As defined in Section 4.1.

end_seq: 16 bits As defined in Section 4.1.

lost_packets: 32 bits Number of lost packets in the above sequence number interval.

dup_packets: 32 bits Number of duplicate packets in the above sequence number interval.

min_jitter: 32 bits The minimum relative transit time between two packets in the above sequence number interval. All jitter values are measured as the difference between a packet's RTP timestamp and the reporter's clock at the time of arrival, measured in the same units.

max_jitter: 32 bits The maximum relative transit time between two packets in the above sequence number interval.

mean_jitter: 32 bits The mean relative transit time between each two packet series in the above sequence number interval, rounded to the nearest value expressible as an RTP timestamp.

dev_jitter: 32 bits The standard deviation of the relative transit time between each two packet series in the above sequence number interval.

min_ttl_or_hl: 8 bits The minimum TTL or Hop Limit value of data packets in the sequence number range.

max_ttl_or_hl: 8 bits The maximum TTL or Hop Limit value of data packets in the sequence number range.

mean_ttl_or_hl: 8 bits The mean TTL or Hop Limit value of data packets in the sequence number range, rounded to the nearest integer.

dev_ttl_or_hl: 8 bits The standard deviation of TTL or Hop Limit values of data packets in the sequence number range.

4.6. Statistics Summary Report Block​

4.6. Statistics Summary Report Block