Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
1.6.5.4 Alignment, Framing, and Transmission Functions
Details of the alignment, framing, and transmission function of the LCS Protocol are covered in the “LCS
Protocol Specification -- Protocol Version 2”, available from PMC-Sierra, Inc.
1.7 THE OUT-OF-BAND (OOB) BUS INTERFACE
The Out-of-Band (OOB) bus provides a mechanism for a local CPU to control some or all ETT1 devices
within a switch fabric. The OOB bus provides about 1Mbyte/sec of bandwidth which should be sufficient for
the intended task. The OOB is a “local” bus in the sense that it only interconnects devices that are
co-located on the same printed circuit board. A complete fabric will consist of many boards and therefore
many separate OOB buses. The multiple OOB buses could be extended into a single logical bus via the
use of a “satellite” bus controller on each board as shown in Figure 32. Alternatively, each OOB bus could
be controlled by a local CPU and the CPUs could then communicate with the other CPUs via some other
mechanism such as an Ethernet network. This document describes only the “local” OOB bus.
All of the ETT1 devices have an OOB interface. The ETT1 devices are slave devices and so there must be
a local master device, such as a satellite controller, that initiates bus transactions.
Figure 32. One Implementation: The OOB Bus Consists of Both Local and Global Buses
PCB
ETT1
ASIC
Satellite
Controller
ETT1
ASIC
local
OOB
bus
PCB
(master)
global
OOB
bus
Central
CPU
Controller
PCB
ETT1
ASIC
Satellite
Controller
(master)
ETT1
ASIC
local
OOB
bus
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
77
PMC [ PMC-SIERRA, INC ]
