PM9313 datasheet(60/343 Pages) PMC

60 / 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.

The EPP contains two TDM tables so that one table can be used by the fabric while the system software is

configuring the other table. All EPPs must use the same table at the same time. A TDM LCS Control

Packet is used to specify which of the two tables is being used at any given time.

At the start of the Frame, a TDM pointer in each port begins at entry 0 in the table and advances one entry

every cell time. During every cell time, if the “current” TDM table Send entry is valid, the EPP checks to see

if the cell at the head of the appropriate TDM queue has a TDM flow ID (tag) that matches the entry in the

table. If not, then nothing special is done. If they do match then the EPP informs the Scheduler that it will

be sending a TDM cell at some fixed time in the future. This prevents the Scheduler from trying to schedule

a best-effort cell from that port at the same time. Figure 27 shows the logic at the ingress port.

Subport

Identifies the source subport (if in subport mode, else 0)

Output

VLD

1 if the output side TDM entry is valid

Input Port

Input port that the output expects to receive from

Output

vector

A four-bit vector which defines the fanout of the subports that should receive

aTDM cell.

Table 2.

TDM Reservation Table (Continued)

Field

Size (bits)

Meaning

PM9313 Datasheet(PDF) 60 Page - PMC-Sierra, Inc