Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
linecard and the switch core CPU, and (3) Single Phase Control Packets which are used as a special form
of LCS Control packets for timing sensitive information.
1.6.3.1 LCS Control Packets
LCS CPs are specified by setting the Label_1/Label_2 Field to 14’h0000 (CP-category for LCS Control
Packets) and associated Type Field to 4’h0 (Type for Control Packets). Table 11 describes the contents of
the first 10-bytes of the LCS segment payload for an LCS CP format.
Table 11. LCS Control Packet Format
Size
(bits)
Field
Definition
CP_Type
8
Indicates the type of LCS Control Packet (e.g. TDM)
CP_Type Extension
56
Indicates the information carried with this type of control packet. Unused bits
must be set to zero.
a
CRC-16
16
16-bit CRC calculated over 10-byte control packet payload.
a. See Section 1.6.4.1 “Use of CRC-16 Field” on page 73 for details of CRC calculation.
Because there is no flow control mechanism for LCS CPs sent to the switch fabric, and a CP request/grant
does not distinguish the CP_Type, care must be taken so as not to overflow the receiving CP queues. At
most, only one request for each CP_Type should be outstanding.
In what follows, the three CP_Types of currently defined LCS CPs are described.
NOTE: The actual LCS headers for Switch-to-Linecard Control Packets are not built in to the EPP.
Instead, the EPP expects to find the headers, preconfigured at specific queue locations
within the Dataslices. Thus, part of the initialization sequence of a new ETT1 port card is
to write the values of the Control Packets into the Dataslice queues. Section 3.3 “Output
Dataslice Queue Memory Allocation with EPP” on page 162, provides details of these
locations.
70
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
PMC [ PMC-SIERRA, INC ]
