Released
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
TDM Control Packets
The format of TDM CPs is described in Table 12.
Table 12. TDM Control Packet Format
Size
(bits)
Field
Definition
CP_Type
TDM Frame Sel
Unused
8
1
00000000
Indicates which TDM frame to use.
Set to zero.
55
16
CRC-16
16-bit CRC calculated over 10-byte control packet payload.
Note that when a TDM CP is sent from the linecard to the switch core, no reply is generated by the switch
core.
Request Count Control Packets
Request Count CPs are only sent from the linecard to the switch, and are used to keep request counter
values consistent between the linecard and the switch core. When the switch core receives this CP, it
updates the corresponding request counter (specified by Label_1 and Type_1) with the count field. This
control packet can be sent periodically or when the linecard suspects that the linecard and switch core
have different values (e.g. following a CRC error).
Request Count CPs are required for unicast traffic and also required for multicast and TDM requested
traffic when supported. For unicast traffic, the Label_1 field is set as described in Table 8. For multicast
traffic, the Label_1 field is undefined and should be set to zero. The format of the Request Count CP is
described in Table 13
Table 13. Request Count Control Packet Format
Size
(bits)
Field
Definition
CP_Type
Label_1
Type_1
Count
8
00000001
Label for request counter.
14
4
10xx unicast 11xx multicast
14
24
16
Update counter value, always set to zero for multicast.
Set to zero.
Unused
CRC-16
16-bit CRC calculated over 10-byte control packet payload.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
71
PMC [ PMC-SIERRA, INC ]
