Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
1.6.5 LCS PHY Layer
The LCS PHY provides a high-speed parallel transfer of data in the form of framed, fixed-sized segments
that have been channelized across multiple media connections. Higher segment rates are also supported
through trunking options, while lower segment rates are supported through multiplexing options.
The channelization, framing, and transmission functions of the LCS PHY have been specified to allow use
of a variety of available Serdes (serialization/deserialization) and parallel fiber optics components. Portions
of this specification will refer to examples of media types. The LCS PHY specification does not preclude
other compatible options.
Channelization requirements include the mapping of segments to multiple channelized frames, channel
skew specifications, and interchannel (segment) alignment operation.
Frame alignment, encapsulation, retiming and the required code-points for a parallel, full-duplex interface
are included in the framing function.
Transmission requirements include the clocking requirements and electrical characteristics of the parallel
interface.
The parallel interface used by the LCS PHY is based on widely available Serdes implementations that
include their own endec (encoder/decoder) functionality. These components also fit well with the available
and emerging parallel fiber optics components. Optionally, an LCS device can include the Serdes and
8B/10B Endec functions, but these are not strictly required by the LCS specification. In fact, LCS
implementations that forego the use of optical transceivers or Serdes and endecs altogether for single
board design are also compliant with the LCS specification.
1.6.5.1 Link Speed
The LCS PHY for ETT1 supports one in link speed option, 1.5 Gbaud. This link speed has various
requirements that affect channelization and framing functions, discussed here and in the LCS
specification. Serdes and optical transceiver components are available to support the 1.5 Gbaud links.
1.6.5.2 Segment Payload Options
The LCS Protocol for ETT1 uses an eight byte prepend and supports two segment payload sizes, a
64-byte payload with an eight byte LCS prepend (8+64 byte segment) and a 76-byte payload with an eight
byte LCS prepend (8+76 byte segment). Discussion of these options is also covered in the channelization
and framing sections here and in the LCS specification.
1.6.5.3 Segment Channelization
The LCS Physical Layer includes the external interface for receiving and transmitting LCS segments from
and to the linecard. The interface consists of parallel “ganged” interfaces that each carry a serialized
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
75
PMC [ PMC-SIERRA, INC ]
