TABLE OF CONTENTS Enrique J. Hernandez-Valencia,
Lucent Technologies
The Generic Framing Procedure (GFP) is a new protocol recently standardized under ITU-T G.7041/Y.1303 [1] and ANSI Tl. 105.02 [2] and designed to support variable- and fixed-length packet transport modes over a general-purpose bit or byte synchronous high-speed communications channel. GFP extends the HEC-based packet delineation mechanism used by other broadband applications such as ATM [3] to variable-length data transport applications. GFP exploits the ability of modern point-to-point transmission links to deliver the incoming information stream in a sequential and orderly fashion to greatly simplify data link layer synchronization and frame boundary delineation operations. Unlike packet delineation mechanisms based on the HDLC framing procedure [4, 5], GFP requires no special line encoding for the framed protocol data units (PDU), which substantially reduces processing logic requirements for the data link mapper/demappers. Unlike ATM, GFP delegates high-touch QoS management functions to the client layers, which further reduces operational overhead. The lower implementation complexity makes GFP particularly suitable for high-speed transmission links such as SONET/SDH [6, 7] point-to-point links, wavelength channels in an optical transport network [8], or even dark fiber applications [9]. For high data rate environments, GFP is a very attractive alternative to solutions such as ATM, Frame Relay [10], PPP/HDLC [11], PPP-over-SONET (POS) [12], or X.85/X.86 [13, 14].
From a hybrid Packet/TDM system perspective, as illustrated in Figure 5-1, two aspects are of key relevance when discussing transport mechanisms for packet-or i en ted traffic over a TDM-based telecommunications infrastructure: (1) the...
