VSC7511 datasheet(115/324 Pages) MICROSEMI

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Functional Descriptions

VMDS-10488 VSC7511 Datasheet Revision 4.2

100

A new command must not be setup until after the VCAP_UPDATE_CTRL.VCAP_UPDATE_SHOT field

has automatically cleared. Also note that the cache is used by the VCAP while a Move operation is being

performed. As a result, any value in cache prior to a Move operation is lost, and a write is not permitted to

the cache while a Move operation is performed.

The following illustration shows an example of a Move operation.

Figure 32 •

Move Down Operation Example

A Move operation can be performed hitlessly during frame traffic, that is, all entries and actions are still

available during a Move operation, and all hits are counted by the action hit counters. The TCAM entries

at the original positions are invalidated after the Move operation is complete.

During heavy frame traffic, it can take some time for a large move operation to complete, because the

moving of individual rows are restarted each time a lookup is performed. If it is not important that the hit

counters are accurately updated while the move operation is processed,

VCAP_UPDATE_CTRL.MV_TRAFFIC_IGN can be set. This prevents the VCAP from restarting moves

and consequently, decreases the time it takes for the move operation to complete. It may, however, lead

to inaccurate hit counter values. Note that even if MV_TRAFFIC_IGN is set, the VCAP still processes all

lookups correctly.

Default actions can also be moved, however, VCAP_UPDATE_CTRL.UPDATE_ENTRY_DIS must be

set.

If a row is moved to a negative address (above address 0), the row is effectively deleted. If a block is

partly moved above address 0, the block is also only partially deleted. In other words, the rows that are

effectively moved to an address below 0 are not deleted. If one or more rows are deleted during a move

operation, the sticky bit VCAP_STICKY.VCAP_ROW_DELETED_STICKY is set.

3.8.7.2

Initializing A Block of Entries

A block of entries can be set to the value of the cache in a single operation. For example, it can be used

to initialize all TCAM, action, and counter entries to a specific value. The block of entries to initialize can

also include the default action and counter entries.

To perform an initialization operation:

•

Set VCAP_UPDATE_CTRL.UPDATE_ADDR equal to the address of the entry with the lowest

address, among the entries that should be written.

•

Set VCAP_MV_CFG.MV_SIZE to the number of entries that must be included in the initialization

operation: n + 1 entries are included.

•

Set UPDATE_ENTRY_DIS, UPDATE_ACTION_DIS, and/or UPDATE_CNT_DIS to select if the

TCAM, action RAM, and/or the counter RAM should be excluded from the initialization operation.

•

Set VCAP_UPDATE_CTRL.UPDATE_CMD to the initialization operation.

•

Start the initialization operation by setting VCAP_UPDATE_CTRL.VCAP_UPDATE_SHOT.

...

255

254

253

252

251

250

249

248

247

246

...

256

283

...

TCAM

Action

RAM

Entry+Mask+TG

Action, Counter

Entry+Mask+TG

Action, Counter

Default

Actions

Original

position

New

position

UPDATE_ADDR = 247

MV_NUM_POS = 4

MV_SIZE = 2

VSC7511 Datasheet(PDF) 115 Page - Microsemi Corporation

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