PM9313 datasheet(20/343 Pages) PMC

20 / 343 page

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

PM9311/2/3/5 ETT1™ CHIP SET

PMC-2000164

ISSUE 3

ENHANCED TT1™ SWITCH FABRIC

Released

Data Sheet

PMC-Sierra, Inc.

1.1.2

The Switch Core Model

The ETT1 Chip Set is designed to provide a switch core, not a complete packet switch system. A complete

switch consists of one or more switch cores, together with a number of linecards. Each linecard connects

to one port in the core. The linecard includes a physical interface (fiber, co-axial cable) to a transmission

system such as SONET/SDH or Ethernet. The linecard analyzes incoming cells or packets and determines

the appropriate egress port and priority. The linecard contains any cell/packet queues that are needed to

allow for transient congestion through the switch.

The ETT1 switch core operates on fixed size cells. If the linecard transmission system uses variable length

packets, or cells of a size different from those used in the core, then the linecard is responsible for

performing any segmentation and reassembly that is needed. Figure 1 illustrates this generic

configuration.

Figure 1. The Basic Components of a Switch Built Around the ETT1 Chip Set.

The ETT1 Chip Set has been designed to allow for up to 200 feet (70 meters) of physical separation

between the ETT1 core and the linecard. The LCSTM(Linecard to Switch) protocol is used between the

ETT1 core and the linecard to ensure lossless transfer of cells between the two entities. However, while

the LCS protocol must be implemented, the physical separation is not mandatory; the linecard could reside

on the same physical board as the ETT1 port devices.

The switch core has two main interfaces. One is the interface between the linecard and the core port,

described in the LCS Protocol section.

SONET/SDH

Ethernet....

SONET/SDH

Ethernet....

ETT1 Switch Core

CPU

OOB Bus

LCS Protocol

Linecard 0

Linecard 31

port 0

ETT1 Chip Set

PM9313 Datasheet(PDF) 20 Page - PMC-Sierra, Inc