Hello my name is Jay Campbell with The Fax Guys for RightFax University.
This video will demonstrate the basic use of the Wireshark application for troubleshooting and information gathering for Fax over IP issues.
This video was recorded at 1280 by 720 resolution for High Definition and is best viewed in full screen mode.
Wireshark is a network protocol analyzer for Unix and Windows and is free to download at www.wireshark.org.
Wireshark is de facto standard across many industries and educational institutions. The Fax Guys use Wireshark for troubleshooting fax over IP issues as this is the logging standard that both OpenText, the makers of RightFax, and Dialogic who produce and support the Brooktrout series of faxboards, the SR140 "boardless" faxing solution and the Dialogic media gateways.
Let's take a look at the tool, and what sort of logging we can gather and review with it.
Once the tool is installed and running on the RightFax server, we first want to select the
interface that represents the IP address of the network interface device that the fax server is using to communicate with your media gateway for faxing.
Select the interface from the Interface List, and select start.
What we are primarily concerned with for fax over IP is going to be under Telephony > VOIP calls. (Fax over IP uses Voice over IP functionality to communicate with the media gateway we are using in conjunction with the fax server to send and receive faxes.)
Once you have gathered the trace logging as needed, save the file, and then open the log and you will see all of the calls gathered during the logging period, in this example, we have 1 call listed.
Now let's take a look at the call in the trace, and what we would typically review. Once you open the call, you can see a few options along the bottom of the call applet. We see Prepare Filter, Flow, Player, Select All and Close. For the scope of this video, we are primarily concerned with Flow. With the call highlighted when we click on Flow, we actually see the call flow. The call flow shows the IP addresses of the interfaces connected to the server, the server IP, and the flow of the call. The flow is represented graphically by the arrows moving from one IP to another. In this example, we see an inbound call from the IP of 172.28.95.178 to the RightFax server's SR140 IP, 172.28.231.1. We also see that the fax server and SR140 are also communicating with another network segment at 172.28.231.13. This is typical flow with a call manager at the initiating side of the call at 126.96.36.199 and a media gateway or router of some sort at 172.28.231.13.
During the course of a call we can expect to see certain responses back and forth between the sender and recipient, and we need to see these items in a certain order if a fax is to be transmitted or received succesfully; we aren't going in to all of these details on the call flow in this particular video, look for another installment covering the phases of the call, and the responses we would expect to see in a good call while tracing. We also already have a very good video covering filtering search results in Wireshark, it's worth a view as well.
We can see all of the back and forth communication between the segments in this call, from the start of the call to the end. Keep in mind, we can only see the responses back and forth to the fax server directly, so there could be issues outside of this view if the problem you are experiencing is occuring further out on the network or even at the provider/carrier level.
Note as well that you can further investigate each specific item as the trace is very robust in what is gathered. Take a look here at the DCN (Disconnect signal) being sent from the call manager to the router. By selecting this item, we can actually drill all the way into this packet to further try and isolate our issue.
Let's go back to the call listing and take a look at one other useful and interesting feature. With a call selected, you can also use the Player option to view and listen to the audio stream of a call. Since faxing at it's core uses an audio stream, this can be helpful troubleshooting some issues.
That is all for the basics of Wireshark usage for troubleshooting although there are further in-depth features and functions of the tool this should give you a base understanding of what the tool does and why we call for Wireshark tracing on all fax over IP support issues along with the logging generated by the faxboard or boardless solution, and the logging available from the RightFax software.
This is Jay Campbell with The Fax Guys for RightFax University saying thank you for watching and Please visit us again. The RightFax University is a work under continual progress and we update often.