Microsoft KB Archive/896341

= A video session stops responding when an ISA Server 2000 Firewall client connects to a Web site that supports the H.323 protocol =

Article ID: 896341

Article Last Modified on 12/13/2005

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APPLIES TO


 * Microsoft Internet Security and Acceleration Server 2000 Service Pack 1
 * Microsoft Internet Security and Acceleration Server 2000 Standard Edition

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SYMPTOMS
Consider the following scenario. A client computer that resides behind a Microsoft Internet Security and Acceleration (ISA) Server 2000 server connects to a Web site that supports the H.323 protocol. Additionally, the ISA Server 2000 server is configured as an H.323 gatekeeper. In this scenario, the video session may stop responding. Additionally, you may be able to chat with online meeting participants only by using standard text messages.

Notes
 * The H.323 protocol is an International Telecommunications Union (ITU) standard that provides specifications for computers, for equipment, and for services that enable multimedia communication over networks. Users can connect with other users over the Internet and then use various products that support the H.323 protocol.
 * Sites that offer video relay service, for example, typically support the H.323 protocol.



CAUSE
This problem occurs if the ISA Server 2000 server does not use the port that was negotiated with the ISA Server Firewall client for RTP transmission but instead uses a different port.

Note This issue occurs if the ISA Server 2000 server does not use the port that was negotiated with the ISA Firewall client for Real-Time Protocol (RTP) and instead uses a different port.



WORKAROUND
To work around this issue, upgrade to Microsoft ISA Server 2004.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For more information about ISA Server 2004, visit the following Microsoft Web site:

http://www.microsoft.com/isaserver/default.mspx

Keywords: kbtshoot kbprb KB896341

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