VSC7440 datasheet(189/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

172

3.22.1.2 CAM Row

Under some circumstances, it might be necessary to store more entries than possible on a MAC table

row, in which case entries are continuously changed or automatically updated.

To reduce this issue, one additional MAC table row (named CAM row) exist with entries that can be used

to extend any hash chain, and thereby reduce the probability for hash depletion where all the buckets on

a MAC table row are used. These entries on the CAM row can be used as any other MAC table entries.

CAM row usage is controlled separately (by ANA_L2::LRN_CFG.AUTO_LRN_USE_MAC_CAM_ENA,

ANA_L2::LRN_CFG.CPU_LRN_USE_MAC_CAM_ENA and

ANA_L2::LRN_CFG.LRN_MOVE_CAM_ENTRY_BACK).

3.22.2

MAC Table Updates

Entries in the MAC table are added, deleted, or updated by the following methods.

•

Automatic (hardware-based) learning of source MAC addresses; that is, inserting new (MAC, FID)

pairs in the MAC table

•

CPU access to MAC table (for example, CPU-based learning and table maintenance)

•

Automated age scan.

3.22.3

CPU Access to MAC Table

This section describes CPU access to the MAC table. The following table lists the applicable registers.

ADDR_TYPE

This field encodes how to interpret the ADDR field.

Encoded as:

ADDR_TYPE= UPSID_PN(0): Unicast entry address. Used to associate the entry with a

unique {UPSID, UPSPN} port.

ADDR(9:5) = UPSID

ADDR(4:0) = UPSPN

ADDR_TYPE=GCPU_UPS(1): CPU management entry address. Used to associate the

entry with a unique global CPU port or internal port.

ADDR(9:5) = UPSID

ADDR(11) = 0:

ADDR(3:0) = CPU port number.

ADDR(11) = 1:

ADDR(3:0) = 0xe: Internal port number.

ADDR(3:0) = 0xf: Local lookup at destination unit (UPSID).

ADDR_TYPE=GLAG(2): Unicast GLAG address. Used to associate the entry with a global

aggregated port.

ADDR = GLAGID.

ADDR_TYPE=MC_IDX(3): Multicast entry address. Used to associate the entry with an

entry in the PGID table. Specifies forwarding to the ports found in the PGID table entry

indexed by mc_idx.

ADDR = mc_idx.

Table 109 •

MAC Table Access Registers

Target::Register.Field

Description

Replication

LRN::

COMMON_ACCESS_CTRL

Controls CSR access to MAC table.

Table 108 •

MAC Table Entry (continued)

Field

Bits

Description

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