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    ProShare(TM) Video: TCP/IP Requirements

    Contents:

    • PROSHARE VIDEO SYSTEM TCP/IP REQUIREMENTS
    • INTRODUCTION
    • THE WINSOCK APPLICATION INTERFACE
    • PROPRIETARY APPLICATION INTERFACES
    • BUT... MY FAVORITE VENDOR ISN'T SUPPORTED!
    • WE'RE WORKING ON MORE TCP/IP SOLUTIONS
    
    

    PROSHARE VIDEO SYSTEM TCP/IP REQUIREMENTS

    
    

    INTRODUCTION

    
       The ProShare Conferencing Video System provides video conferencing using
    
       existing LAN infrastructure and standard LAN communication protocols:
    
       Novell* NetWare* IPX, TCP/IP, and NetBIOS.  The TCP/IP protocol is
    
       available from many vendors and has a standard application interface
    
       known as WinSock.  Unfortunately, the WinSock interface can't
    
       consistently meet the real time requirements of video conferencing.  In
    
       addition to WinSock, many vendors provide proprietary interfaces.  For
    
       rel1.8, the ProShare Video System supports TCP/IP from two vendors using
    
       their proprietary interfaces.  Over the next year, Intel will be working
    
       with communications vendors to encourage more of them to provide the
    
       real time support required for video conferencing.  In the long term,
    
       Intel is working with Microsoft*, Novell, and others on the definition
    
       of WinSock II.  This new interface standard will be suitable for video
    
       conferencing, allowing ProShare Video Systems to provide
    
       vendor-independent TCP/IP connections.
    
    
    
    

    THE WINSOCK APPLICATION INTERFACE

    
       Many vendors support the TCP/IP protocol, and interoperability between
    
       two systems using TCP/IP is usually a given, even if different vendors
    
       supplied the communications stacks.  A standard, vendor-independent,
    
       application interface known as WinSock makes this interoperability
    
       possible.
    
    
    
       Unfortunately, WinSock can't consistently meet the real-time
    
       requirements of ProShare video conferencing.  Using WinSock,
    
       applications transfer data to and from the communications stack using
    
       Windows* messages.  When the communications stack receives data from the
    
       network, WinSock sends a Windows message to the appropriate application.
    
        If that application isn't currently executing, it won't see the message
    
       immediately.  In general, with several applications running in Windows,
    
       it could be a long time before the application receives the message from
    
       the communications stack.  The same problem occurs with data flow from
    
       the application to the network.  When an application has data to send to
    
       the network, it notifies the communications stack by sending a Windows
    
       message.  Again, the message might take a long time to get to the
    
       communications stack.
    
    
    
       Much of the power of ProShare video conferencing comes from being able
    
       to share applications, use a shared notebook, or transfer files while
    
       talking with and viewing the other person.  The user can also be running
    
       other applications at the same time.  Some applications, originally
    
       written for the single-tasking DOS environment, monopolize system
    
       resources.  In this multi-tasking environment, the timely flow of
    
       messages across the WinSock interface can be disrupted.  This problem is
    
       compounded by the fact that Windows does not offer pre-emptive
    
       scheduling of tasks.  For example, if the ProShare application used the
    
       WinSock interface, audio or video streams could be lost while the user
    
       held a mouse button down in a word processing application.
    
    
    
    

    PROPRIETARY APPLICATION INTERFACES

    
       Fortunately, many vendors support proprietary interfaces to their
    
       communications stacks, in addition to WinSock.  These interfaces provide
    
       an alternative to the Windows message protocol for transfering data. 
    
       When the communications stack has data ready for the application, the
    
       stack can transfer the data immediately.  The stack can also receive
    
       data from the application immediately when the application has data
    
       ready to send.
    
    
    
       In Q2 '94, the design team evaluated the proprietary interfaces of
    
       TCP/IP stacks from seven vendors.  At that time, only the Novell and FTP
    
       stacks met the real time requirements for audio, video, and data
    
       conferencing.  Only these stacks allow rel1.8 to support the TCP/IP
    
       standard without sacrificing audio and video quality during a ProShare
    
       video conference.
    
    
    
    

    BUT... MY FAVORITE VENDOR ISN'T SUPPORTED!

    
       There will be cases where the ProShare application doesn't support the
    
       TCP/IP vendor currently being used by a customer.  In these cases,
    
       customers will need to change the communications stack on their ProShare
    
       systems to one of the stacks supported in rel1.8.  There may be issues
    
       with corporate IT standards, but most existing TCP applications use the
    
       vendor-independent WinSock interface and will run, without
    
       modifications, on either of the stacks rel1.8 supports.   A serious
    
       problem does arise if the customer has an existing application that is
    
       using the proprietary interface on a communications stack that rel1.8
    
       does not support.  In that case, the customer can't run both the
    
       ProShare application and the existing application simultaneously because
    
       only one TCP stack can be active.  The biggest problem here is that the
    
       customer may be unaware that the existing application is dependent on a
    
       particular stack.  When the customer changes communications stacks, an
    
       old application might unexpectedly fail to run.
    
    
    
    

    WE'RE WORKING ON MORE TCP/IP SOLUTIONS

    
       Over the next year, Intel will be working with communications vendors to
    
       encourage more of them to provide the real time support required for
    
       video conferencing.  It is Intel's intent to include more TCP/IP vendors
    
       on our supported vendor list with later releases of the ProShare Video
    
       System.
    
    
    
       Intel is also working with Microsoft, Novell, and others on the
    
       definition of WinSock II, the next generation of the WinSock interface. 
    
       This new interface standard will be suitable for video conferencing,
    
       allowing ProShare Video Systems to provide vendor independent TCP/IP
    
       connections.
    
    

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