VSC7440 datasheet(76/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

the rule. For more information about type-group fields for individual VCAPs, see Individual VCAPs,

page 59.

The following illustration shows an example of inserting a 2-bit entry type-group field and a 3-bit action

type-group field for a VCAP with 36-bit entry data/mask and a 64-bit action. After inserting of type-group,

there is room for 34 additional entry/mask bits and 61 action bits in the cache.

Figure 20 •

VCAP Cache Type-Group Example

When programming the entry’s type-group field, the mask bits must be set to zeros, so that the type-

group bits consist of match-1 or match-0, or both.

Use the following procedure for each address that is part of an entry.

Use the entry’s current address offset and size to find the appropriate type-group field and

associated field-width by using the entry type-group table for the VCAP. Skip step 2 if entry type-

group is not applicable for the VCAP.

Insert the entry type-group field into the cache for a type-group field width of n. Write the value of the

type-group field to bit-positions [n-1:0] in VCAP_ENTRY_DAT and write zeros to bit-positions [n-1:0]

in VCAP_MASK_DAT. In this way, type-group field value 1 becomes match-1 and 0 becomes match-

Fill the remainder of VCAP_ENTRY_DAT and VCAP_MASK_DAT with appropriate entry data. There

will be room for (entry width – type-group width) additional bits of entry data.

Use the following procedure for each address is that is part of an action.

Use the action’s current address offset and size to find the appropriate type-group field and

associated field-width by using the action type-group table for the VCAP. Skip step 2 if action type-

group is not applicable for the VCAP.

Insert the action type-group field into the cache. For a type-group field width of n. Write the value of

the type-group field to bit positions [n-1:0] in VCAP_ACTION_DAT.

Fill the remainder of VCAP_ACTION_DAT with appropriate action data. There will be room for

(action width – type-group width) additional bits of action data.

Counters never use type-group encoding.

3.12.3

Individual VCAPs

This section provides detailed information about the individual VCAPs; VCAP CLM, VCAP IS2, VCAP

LPM, and VCAP ES0. The CLM, IS2, and LPM VCAPs share resources. For more information, see

Sharing Resources, page 57.

VCAP_ENTRY_DAT

VCAP_MASK_DAT

VCAP_ACTION_DAT

idx: 0

idx: 1

idx: 0

idx: 1

idx: 0

idx: 1

Entry Data

Entry Mask

Action

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