Hi Mark,
Yes, you likely can use wireshark to figure out what is going wrong with your calls. No you don’t need a PhD.
Start off by reading these 3 links
http://wiki.wireshark.org/CaptureSetup
http://wiki.wireshark.org/CaptureSetup/WLAN
http://wiki.wireshark.org/CaptureSetup/Ethernet
when you capture from eth0 you are capturing anything that goes to that port on the switch (the 4 ports you are using on the back of your device is a small switch) but not everything that’s on the network. You can see the DHCP traffic because it is broadcast to everyone but when your phone makes a connection it will go from the wireless directly to the router and out to the internet with out showing up on any other ports.
Getting a hub (careful what you buy some ‘hubs’ on the market today are switches) or tap would be the cheap way to go but you may want to (or need to) invest in a wireless adapter that will let you do true captures.
Hope that helps get you started
tim
From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Mark Phillips
Sent: Friday, January 28, 2011 1:07 PM
To: Wireshark user Group
Subject: [Wireshark-users] Newbie Questions for a Specific Problem
I am new to wireshark and network monitoring, so please bear with me. I am looking for some guidance on how to solve a specific network problem...
The problem
My T-Mobile MYTouch 4G is supposed to be able to make calls over wifi. It connects to some wifi hot spots, but not others. In particular, it connects at a local Stabucks for wifi calls, but now my office wifi network. I need to find a way to make it work over my office network. The kicker is the phone says I am connected to wifi at both locations, but just can't make a phone call using wifi over my office network. Basically, one enables Wifi, and the phone scans and connects to a network. This process succeeds in both locations. There is a second button to enable wifi calling, which fails on my office network, but not at Starbucks. The error I message when it does not connect is "Connection Error - ISP or T-Mobile Network Error." T-Mobile technical support says it is a problem with my network, so I am SOL. But, they cannot tell me what my network has to do to be compatible with wifi calling.
I thought I might be able to use wireshark see what happens when the phone connects at Starbucks and not on my office network, to see if I can change my network to work with wifi calling. My network setup - Linksys WRT54G Wireless Router configured as an access point connected to a BEFSX-41 Linksys router, which is connected to my cable modem. I use MAC filtering and WPA and AES with a pre-shared key for wireless security.
Questions...
1. Is my initial assumption that I can use wireshark to figure out what is not working with my network and what is working at Starbucks for wifi calls even feasible? Do I have a chance of figuring out what needs to be changed on my network to make wifi calling work?
2. Do I need a PhD in LAN Diagnostics to figure out what is happening on my network versus Starbucks and fix my network?
3. I fired up wireshark on my work network and starting capturing packets on eth0. I looked at the DHCP routing table in the router and found the phone was assigned 192.168.25.203. I set a filter for that address (ip == 192.168.25.203 or eth.addr == f8:db:7f:42:db:75), hit a web page on the phone and no packets were captured, even though the phone says it was connected to the wireless network. The page loaded on the phone. Tried sending/receiving an email. I also tried hitting the "enable wifi calling" button, and no packets. What am I doing wrong?
Thanks,
Mark
