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Channel Server

The functions of the channel server are:

• Allocation of codecs to each site in a conference
• Control/specification of a codecs:
  • Data rate
  • Coding scheme
  • Destination Address (Phone number, or IP addr/port)
  • Source Address of incoming traffic (for security)
• Control over when a codec starts and stops sending
• Control of physical/virtual switch controllers
• A naming service for endpoints
• Issue QOS requests to network management servers (where available)

Conceptually, the channel server is a big virtual video telephone exchange. What the channel server does not do is perform any form of booking service - that is performed (if required) by a separate subsystem, which the conference server can poll for "hints". Initially the channel server will be configured from static tables. Later the static tables will be supplemented with dynamic data from the booking system.

The static configuration tables of the channel server will contain the following information:

• End point name (a text string, free format)

  For each end point:

  • Network type {IP ISDN}
  • Coding scheme {H261 possibly others }
  • Coding scheme specific restrictions (if any)
  • Remote Address:
    • IP address and Port, or
    • ISDN number
  • Local Address
  • Recommended data rate
  • A specific CMMC codec list (only really intended to be specified to avoid incompatibilities, but will initially be used for static configurations)

Note that all this information need not necessarily be already stored in the channel server's configuration table, but where it is not available, the remote codec controller must be capable of supplying this information using the MIC-1 protocol described below. Codecs such as ISDN videophones which cannot comply with the MIC-1 protocol must be manually specified in the table before use. When the booking system becomes available, it will be possible to remotely configure channel server configuration tables using the booking system. An email booking system interface is proposed to lessen this sort of bootstrapping problem.

• Channel Server Protocols
• Implementation and Failure Modes
• Protocol MIC-0 - The interface to the CCS
• Protocol MIC-1 - Codec Control Protocol
• Proxy MIC-1
• Protocol MIC-4 - Switch Control Protocol
• Protocol MIC-6 - Manual Control Interface