Content sharing not working on first attempt

[John Shur]

Hi All - having a strange problem - Company A and company B - both behind VCS-E's which are neighbored to each other.  In a new conference or pt-pt call, Company B cannot successfully share presentation with A - (black screen sent) UNTIL Company A shares presentation with B! Then presentations work in both directions!  Any one see anything like this? Any hints on where to look?

BTW - not endpoint related, tried with multiple devices on both sides....

BTW, Company A tested with other suites and presentation sharing works fine no matter who initiates....

Thanks!!

[John Shur · Accepted solution]

Solved - we have a ASA firewall creating a DMZ for the VCS_E and  under service policy rules, global_policy,  it was doing protocol inspections for H.323 H.2225, etc. I turned these off and now sharing works, first time from both directions.

[Martin Koch]

Thank you for giving your feedback.

Strange symptoms are often caused by firewalls, especially layer3 functionality.

Btw, if you use a NAT for the IP of the VCS-E in your DMZ, please remember that

you would need to have the "dual interface option" even with one interface as it

enables an option to specify an external NAT address which all voip traffic has to point to.

(there are a couple of postings regards this in the forum).