Gautam Shiroor – Emulex
FC-FS-4, Jun 04, 2014

This document seeks clarification on the extended frame marker referred to in section 5.5.2, based on the current content of FC-FS-4 version 0.5, document number 14-018v1.

Text in red is the proposed change.

The beginning of a Training Frame shall be signaled by a frame marker. A frame marker shall be trans-mitted by holding the physical medium signal at logical “1” for 16 TUI followed by holding the physical
medium at logical “0” for 16 TUI. This is a deliberate violation of one eighth rate differential Manchester
coding, and carries no information (see figure 33).

< Figure 33>

The Control field and the Status field each contain 16 bits of information (i.e., each contain 128 TUI of
differential Manchester coded information). The information in these fields shall be transmitted so that
more significant encoded information bits are transmitted before less significant encoded information bits.
The electrical characteristics of the Transmitter Training Signal are specified in an FC-0 standard, and
when indicated in this standard, are indicated informatively.

An extended marker was added for 32GFC because the 16GFC Training Frame Control field looks the
same as the 32GFC frame marker and a 32GFC port could synchronize on the 16GFC Training Frame
Control field. The extended marker is for 16 TUI as shown in figure <xx> to uniquely identify 32GFC.
32GFC locks onto the frame marker plus extended marker to preclude the potential of a false lock at
16GFC speeds. The extended marker shall be transmitted after the frame marker whenever a 32GFC Training Frame is transmitted.