DP83266 datasheet(111/152 Pages) NSC

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70 Control Information (Continued)

Bit

Symbol

Description

D7–D6

SM1–0

Sort Mode

These bits determine how the MACSI device sorts Indicate data onto Indicate Channels 1

and 2

SM1

SM0

ICHN2

ICHN1

Asynchronous

Synchronous

External

Internal

Info

Header

Low Priority

High Priority

The SynchronousAsynchronous Sort Mode is intended for use in end-stations or applications using

synchronous transmission

The InternalExternal Sorting Mode is intended for bridging or monitoring applications MACSMT frames

matching the internal Ring Engine (MAC) address are sorted onto ICHN0 and all other frames matching

the Ring Engine’s internal address (short or long) are sorted onto ICHN1 All frames matching the external

address (frames requiring bridging) are sorted onto ICHN2 This sorting mode uses the EM ECOPY and

ECIP input signals with external address matching circuitry See the section on External address matching

for a full description of the timing required on these signals (Section 63) Promiscuous mode on ICHN2

does not require any external matching logic to copy frames

The HeaderInfo Sort Mode is intended for high performance protocol processing MACSMT frames are

sorted onto ICHN0 while all other frames are sorted onto ICHN1 and ICHN2 Frame bytes from the FC up

to the programmed header length are copied onto ICHN1 The remaining bytes(info) are copied onto

ICHN2 Only one stream of IDUDs is produced (on ICHN1) but both Indicate Channel’s PSP queues are

used for space (ie PSPs from ICHN1 for header space and PSPs from ICHN2 for info space) Frames

may comprise a header only or a headerainfo For frames with info multi-part IDUD objects are

produced For multi-part IDUDs the Indicate Status field in the IDUD is used to determine which part of the

IDUD object points to the end of the header The remainder of the IDUD is used to determine which part of

the IDUD object points to the end of the header The remainder of the IDUD object points to the Info If

Pool Space is only declared for ICNH1 then only the Headers will be written to memory This is useful for

protocol monitor applications

For example if page crosses occur while writing the header and while writing out the Info the MACSI

device will generate a four part IDUD object (IDUDFirst IDUDMiddle IDUDMiddle IDUDLast) The

IDUDFirst will have a status of ‘‘page cross’’ The first IDUD Middle will have a status of ‘‘end of header’’

The next IDUDMiddle will have a status of ‘‘page cross’’ The IDUDLast will have an ‘‘end of frame’’

status

The High PriorityLow Priority Sort Mode is intended for end stations using two priority levels of

asynchronous transmission The priority is determined by the most-significant z-bit of the FC (zzz e 0xx e

low-priority zzz e 1xx e high priority) Synchronous frames are sorted onto ICHN1 and MACSMT

frames are sorted onto ICHN0

111

DP83266 Datasheet(PDF) 111 Page - National Semiconductor (TI)

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