This doesnot make much sense but maybe someone else can help me understand more.
We have user complaining (more and more) about Lync desktop presentation doesnot work when inside office. We have ASA 5510 running v8.4.6. Not the greatest version of the OS but does the job.
I checked ASA log while user tried to connect or present desktop, ASA most of the time doesnot bark but I did capture some UDP traffic drops (screenshot attached).
I did some research online and seems like I need to open UDP port 50000 to 50059 on external interface. Okey, so I did that even I prefer not to.
But desktop sharing/presentation is still broken...and now I do not see ASA drop anything either...
Interesting add-on, if both the viewer and presenter are behind ASA or one is behine ASA and the other is on Cisco remote VPN, there is no issue...
Im confused. Your LAN (office based) users are having Desktop sharing issues and you have an internal ASA? Or are your users on a VPN? Do you have Edge Servers in your Lync topology?
Take a look this for call flows: