Wireshark

I've been having some issues with Voice Over IP (VOIP) at work.  We went with a proprietary system since we have an existing analog Nortel phones and PBX system we wanted to keep a bit longer.  So, our phone guy suggested MCK / Citel model PBX Gateway II and Extender 7000 devices which interface with the analog system and convert the voice to IP Packets using standard compression codecs.  The system requires QoS (Quality of Service) to be implemented (as I'm sure any VOIP system would) to perform properly.  Our phone guy suggested a Q1300 QoS box by Kentrox to manage the traffic.

I've been through a few reconfigurations with this hardware and some changes in ISP's along the way.  However I've never really gotten the system to work satisfactorily to date.  Several discussions with the support from both Citel and Kentrox, both of which have been very helpful every time I've called.  Currently we have a dedicated 5MB fiber EtherMAN between offices.  So, I've put the extender's IP on the same LAN as the main office and the rest of the remote office is behind a firewall device that I have set to limit the Egress and Ingress bandwidth to 3Mbps and tag it as BE.  I have the rest of the main office behind a firewall that also limits the bandwidth to 3Mbps and tags it as BE too.  The QoS box limits all traffic that isn't coming from or bound for either the Extender of the Gateway to 3Mbps as well.  All traffic between those two devices is tagged as high priority and put in the high priority queue.  All other traffic is tagged as BE (Best Effort) witch is lowest or next to lowest priority and put into the associated queue.  I've statically fixed all the ports to a fixed rate to eliminate any issues with auto detection.

With all that the sound quality is good, while the connection stays up.  The problem I'm trying to solve now is the Extender will loose connection suddenly 3-4 times a day, dropping all active calls.  There are no detected errors on the Ethernet line it's self, and no errors that I can see with the packets between the Extender and the QoS.  However I do see some transmission errors between the QoS and the Gateway device.

This brings me to the title of this post.  I have a laptop setup with Wireshark, previously known as ethereal.  To sniff all traffic for analysis.  I can't seem to find a hub though, which I would need to see all the traffic.  So, I'm looking for a simple hub, but I might need to buy a managed switch so I can tell it to mirror the traffic from other designated ports to a monitoring port where I can have the laptop plugged in.  Not the least expensive way to go.  I've done some test captures on our LAN, using the latter method, just to see how the analysis would go.