Bionic Buffalo Tech Note #103: Introduction to Pegasus Client Support
Bionic Buffalo Tech Note #103
Introduction to Pegasus Client Support
last revised Tuesday 2003.04.08
©2003 Bionic Buffalo Corporation. All Rights Reserved.
Tatanka and TOAD are trademarks of Bionic Buffalo Corporation
The Time-Warner Pegasus SSP and LSC protocols are similar to some of the DSM-CC protocols. The
similarity is sufficient to allow a single API to support both standards on the client. This Tech Note
discusses extensions to the DSM-CC client API, to provide Pegasus support, and discusses how they
are used by client applications.
Pegasus and DSM-CC Specifications
The DSM-CC specification (ISO/IEC 13818-6) defines four distinct protocols: User-User (U-U), User-
Network (U-N), Download, and Switched Digital Broadcast Channel Change Protocol (SDB CCP). It
also defines extensions to the MPEG protocols. Together, these protocols support provision, delivery,
and use of various services, such as video-on-demand, broadcasting, file transfer, and internet access.
Time-Warner, as part of its Pegasus program, also defines several protocols which have some of these
functions. The functionality of these Pegasus protocols is almost completely a strict subset of the
functionality of the DSM-CC protocols. In particular,
the Pegasus Session Setup Protocol (SSP) is based on the DSM-CC U-N Session protocol
the Pegasus Lightweight Stream Control Protocol (LSCP) is different from the protocol
used to support the DSM-CC U-U Stream class, but uses compatible semantics
There are specifications for SSP and LSCP. Please refer to the bibliography at the end of this Tech
The various parts of DSM-CC are defined using different languages.
The U-N Session Protocol, upon which SSP is based, is defined in terms of the
Specification and Description Language (SDL), along with textual explanations, so that
the interaction of client with server is described. However, no API is defined for clients or
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