Cisco Systems ATA 186 manual Example of rtpcatch, Output Files, Options, 6-13

Chapter 6 Configuring and Debugging Fax Services

Debugging the Cisco ATA 186/188 Fax Services

Step 3 At the DOS prompt of this directory, enter the following command:

:>rtpcatch <cap_file> [<prefix>] [options]

–<cap_file> is the NAI Sniffer capture file.

–<prefix> is the prefix prepended to the output filenames.

Output Files

The output files of rtpcatch include a summary file and audio stream files.

The summary file is <prefix>.sum if <prefix> is specified, otherwise it is file.sum.

Stream files are labeled with an integer tag beginning with 00. Stream files are also tagged with the extension pcm for G.711A/G.711µ-law, 723 for G723.1, 729 for G729, t38 for T.38, and cfr for Cisco Fax Relay.

Options

rtpcatch options include:

•-fax—to output the fax events for a connection.

The output includes "FAX summary 1" as the interleaved event list for all directions, and "FAX summary 2" as the event list for each direction. The reported events include voice codec change, NSE signalling, and fax relay events.

•-port <port0> <port1>—to discard any packets sent from/to this port.

If the NAI Sniffer capture file includes Cisco ATA prserv packets, these packets can interfere with rtpcatch analysis. Some prserv packets might be interpreted as NTE or NSE events. To prevent such interference, you can either disable debugging output on the Cisco ATA (do this by setting the Nprintf configuration parameter to 0), configure your NAI Sniffer to filter out the prserv packets, or run rtpcatch with the -port options.

Note rtpcatch works best for analyzing a single VoIP session. Command-line options can be entered in any order.

Example of rtpcatch

The section contains an example of using rtpcatch and includes an explanation of its output:

Output

C:\>rtpcatch faxpassthru -fax
[	25]open file: 00.723, (G723) 2.213:10000 =>						2.116:10002
[	26]open file: 01.723, (G723) 2.116:10002 =>						2.213:10000
[	29]	<00>	1	silence pkts from	TS 1760 (seq#		3)
[	42]	<00>	2	silence pkts from	TS 4400	(seq#	9)
[	47]	<00>	2	silence pkts from	TS 5600	(seq#	11)
[	55]	<00>	2	silence pkts from	TS 7760	(seq#	15)
[	101]open file: 02.pcm, (G711u)				2.116:10002 => 2.213:10000
[	106]	<02>	2	lost pkts from	seq# 39
[	107]open file: 03.pcm, (G711u)				2.213:10000 => 2.116:10002
[	110]	<03>	1	silence pkts from	TS 19440 (seq# 41)

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide for MGCP (version 3.0)

OL-4803-01 6-13