tcpdumprtcp

Understand tcpdump output for RTCP RR and SR


Can somebody explain the SR/RR parts of this tcpdump output?

Example: tcpdump -n udp -x port 5091 and less 129 -T rtcp

16:58:15.034159 IP 1.2.3.4.5091 > 10.2.3.4.45041:  sr @3665059093.56 3025985984 1003p 160480b 3l 1012s 12j @23811.54+1.80 sdes 12
16:58:23.753766 IP 1.2.3.4.5091 > 10.2.3.4.45041:  rr 5l 1446s 24j @23820.57+1.49 bye 8

Thanks!


Solution

  • I found the information here

    I believe the values (e.g. packet loss) will be seen as "missing" if 0.
    Adding -vvv for further verbose and you get something along the lines of:

    sr 608743728 @3665062971.29 3057007839 124p 19840b 458089647 2l 135s 7j @0.00+0.00 sdes 12 608743728

    Which will be

    rtcp_type;ssrc_sender;ntp_timestamp_reference;media_timestamp_reference;num_packets_sent;num_bytes_sent;ssrc_source;packet_loss;ext_last_seq_recieved;jitter;some_ts;no_bytes_of_source_desc;ssrc_sender