Daily Archives: September 20, 2005

LCS ports used for communication

Gary wondered if there was a kb article that detailed the ports that LCS used to communicate between client and server.  Well Gary, all I could find is a list of the basic ports used when LCS 2005 talks to Windows messenger.  here you go Gary:

Client:The client listens on a dynamic port for SIP traffic. The client sends data to the default port of the server. The default port of the server is 5060.
Server:The server listens on the default port 5060 (TCP). The server sends notifications to a dynamic port of the client. The dynamic port range can be controlled by using Group Policy. However, we recommend that you use TLS instead of TCP.
TLS mode: The client listens over the same connection that is open to the server.  By default, the server listens on port 5061 (TCP). The server will send to the client only over the client’s TLS session.
Whiteboard and Application Sharing:  The Whiteboard and Application Sharing components of Windows Messenger use the T.120 protocol. The port that is used is fixed and cannot be changed.
Protocol: T.120   Port: 1503 (TCP) 
File transfer:  The messenger file transfer protocol uses the Trivial File Transfer Protocol (TFTP) that is running over TCP. The port range is fixed and cannot be changed.
Protocol Ports: TFTP 6891 – 6900 (TCP)
Audio and video: Audio uses a pair of User Datagram Protocol (UDP) ports for a Real-time Protocol (RTP) stream to transmit data. Video uses Real-time Transport Protocol (RTCP) to control the session stream.  By default, the ports that are used are dynamic. However, the ports can be controlled through Group Policy registry settings.
You can use the following policies to control the port usage:
MinSipDynamicPort: Specifies the lowest port that is used for SIP Default:7100 Min1024 Max:65535
MaxSipDynamicPort: Specifies the highest port that is used for SIP Default:7103 Min1024 Max:65535
MinMediaPort: Specifies the lowest port that is used for Audio and Video signaling Default:5350 Min:1024 Max:65535
MaxMediaPort: Specifies the highest port that is used for Audio and Video signaling Default:5353 Min:1024 Max:65535