PM7375-SC datasheet(86/430 Pages) PMC

86 / 430 page

PM7375 LASAR-155

DATA SHEET

PMC-931127

ISSUE 6

LOCAL ATM SAR & PHYSICAL LAYER

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

The Chain End (CE) bit is used by the PCI Host to

indicate the end of a linked list of TDs presented to the

LASAR-155. The linked list can contain one or more

packets as delineated using the M bit. When CE is set

to logic one, the current TD is the last TD of a linked list

of TDs. When CE is set to logic zero, the current TD is

not the last TD of a linked list. When the current TD is

not the last of the linked list, the Host Next TD

Pointer[13:0] field is valid; otherwise the field is not valid.

Note, the Chain End bit cannot be set to logic one when

the More bit is set to logic one.

The Congestion (CG) bit is used by the PCI Host to

indicate whether the cells used to transmit the buffer

data described by the current TD should be used to

indicate congestion using their Payload Type Indicators

(PTIs). Note, this bit is not considered unless the CHS

bit is set to logic one.

When CG is set to logic one, all cells involved in the

transport of the current buffer will contain a PTI field

which indicates congestion. If CG is set to logic zero,

congestion is not indicated. The CG bit cannot be set to

logic one at the same time the CT[1:0] bits are set to 10

or 11. For multiple TD packets, for all TDs of the packet,

the CG bit must be consistent.

CT[1:0]

The Cell Type (CT[1:0]) bits are used by the PCI Host to

determine the cell type as defined below.

00 - AAL5 user cell

01 - Raw user cell

10 - segment OAM F5 flow cell

11 - End to end OAM F5 flow cell

When CT specifies non AAL5 user cells (i.e. 01, 10 or

11), the current TD's Packet Length must be less than or

equal to forty eight octets. The exact number depends

on the CRC type indicated.

PM7375-SC датащи(PDF) 86 Page - PMC-Sierra, Inc