Capture the call with the above limitations in mind:
•
login as root
•
Enter the command: tcpdump –s0 –w /tmp/filename.pcap
•
place a call or perform the action you want recorded (e.g. phonebook lookup).
have a video issue please make an unencrypted call. This way support can decode the media.
•
replicate the issue.
•
Hang up the call (if you are in a call).
Ctrl + C to stop the capture.
•
•
Use WinSCp on windows or scp on linux/OS X to login as root and navigate to /tmp and
download the log.pcap file (e.g. scp root@<Ip-Address-System>:/tmp/*.pcap will copy all
.pcap files from system to the current directory).
•
To analyze the resulting file you can use Wireshark - see next section.
Wireshark call analysis usage
First download and install Wireshark for your system http://www.wireshark.org/download.html. There
are some requirements for OS X (x11 or Xquartz) that may require some additional downloads.
Once you have Wireshark installed and working and have captured a file (see packet capture above),
simply double clicking the file should open it in Wireshark.
You will now see all the packets sent and received by the system. This is useful, but you may want to
filter so that you can see the call setup.
D15029.01 Troubleshooting Guide TC6.0, April 2013.
H.323
There are various methods to create a filter to show only the appropriate packets from the capture. For
H.323 calls you can enter a filter just to see the call signalling of "h225 or h245".
NOTE
if you
•
Now you can see all the gatekeeper messages, call setup messages and the opening of the
media channels. You can investigate them further by opening the packets you are interested
in to see their Q.931 and H.225 information.
•
You can also see a graphic representation of the call by using
detected calls will be shown. You need the complete call for this to work: Capture started
before the call started and stopped after the call was terminated. Highlight the call you are
interested in and click on Flow. Clicking on the various messages you will be taken to that
packet in the capture.
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Troubleshooting Guide TC6.0
Telephony -> VOIP
Call. All
Copyright © 2013 Cisco Systems, Inc. All rights reserved.
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