Curtiss-Wright FHF5-PC4MWB04-00, Hardware Reference Manual

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SL100/SL240 PROTOCOL
Copyright 2017 7-1 FibreXtreme Hardware Reference
7.1
Overview
NOTE : The FibreXtreme SL100 and SL240 PCI and PMC Cards will be referred to
throughout this appendix as PCI. Anything that is exclusive to the PCI or PMC Cards
will be described as such.
The SL100/SL240 Serial FPDP protocol (also known as VITA 17.1) is designed to
provide near optimal throughput while maintaining low overhead. The link transfer rate
for SL100 cards is 1.0625 Gbps, and the transfer rate for SL240 cards is 2.5 Gbps. Since
an 8B/10B encoding scheme is used, this corresponds to a raw data rate of 106.25 MB/s
(1 MB = 10 6 bytes) for SL100 and 250 MB/s for SL240. Based on the protocol presented
here, the usable throughput of this link available to the user is 105 MB/s for SL100 or
247 MB/s for SL240. All ordered sets used by this protocol are standard Fibre Channel
ordered sets with the exception of positive IDLE, which is allowed for a more flexible
receiver interface.
NOTE : The protocol referred to throughout this document is the protocol used by the
transmitter and accepted by the receiver. The receiver does not have to see the protocol
defined here to receive data. Any generic Fibre Channel data stream with an IDLE at
least every 4096 words can be used.
7.2
Ordered Sets Used
Fibre Channel denotes a certain mapping of the transmission words in the 8B/10B
protocol to be ordered sets, which denote special control information for Fibre Channel.
These same ordered sets are used in VITA 17.1, but are assigned different meaning.
There are eighteen ordered sets used by SL240 to denote different information. Twelve of
these ordered sets are used to embed five bits of data—eight start-of-frame (SOF) sets are
used to embed three bits at the start of a frame, and four status-end-of-frame (SEOF) sets
are used to embed two bits at the end of the frame. The SOF ordered sets embed three
FPDP signals - PIO1, PIO2, and DIR.
Note that although the direction signal on FPDP is active low (/DIR), the signal
transmitted on the link is active high (DIR).
The four EOF ordered sets embed the FPDP signal NRDY (once again, the inverted
version of the FPDP interface’s /NRDY) and Transmit FIFO Overflow flag.
There are two additional EOF ordered sets used by SL240 to denote the actual end of
frame. The Mark EOF (MEOF) denotes a frame that has SYNC associated with it, and
the Frame EOF (FEOF) denotes a normal data frame. The other four ordered sets are
inter-frame padding used to denote flow control information and alternate frame
interpretations. Table 7-1 shows the mappings from the Fibre Channel ordered sets onto
the VITA 17.1 ordered sets, along with the meaning associated with each ordered set.