VSC7511 datasheet(112/324 Pages) MICROSEMI

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Functional Descriptions

VMDS-10488 VSC7511 Datasheet Revision 4.2

Note that the type value is not used for all entry types. If the type value is not used for an entry type, write

the entry data from bit 0 of VCAP_ENTRY_DAT.

As an example of how a TCAM entry is laid out in the cache register, the following illustration shows a

TCAM entry of the IP6_TCP_UDP entry type for the VCAP IS2.

Figure 29 •

Entry Layout in Register Example

Generally, the type value must never be masked. However, by masking the type bits a lookup in the

VCAP is able to match several different entry types. For example, the IS2 entry types MAC_ETYPE and

MAC_LLC have the binary type values 0000 and 0001, respectively. By masking bit 0, a lookup is able to

match both entry types.

The entry type used in the preceding example only has one subword per entry in the TCAM. Creating a

TCAM entry with an entry type that has several subwords per TCAM entry is a little more complicated. As

shown in the following example, the ARP entry type of the VCAP IS2 is used. The ARP entry type has

two subwords per TCAM entry. From Table 70, page 96, it can be seen that the ARP entry type has a

width of 163 bits per subword. A row in the IS2 TCAM is 384 bits wide. For more information, see

Table 69, page 96. Each subword is assigned to half a TCAM row; that is, subword 0 is assigned to bits

0-187 and subword 1 is assigned to bits 188-375. Because the ARP entry only is 167 bits wide, there are

21 unused bits for each subword, as shown in the following illustration. The layout for VCAP_MASK_DAT

is similar to VCAP_ENTRY_DAT. In addition, a type-group value is associated to each subword. The

type-group values are laid out back-to-back in VCAP_TG_DAT as shown in the following illustration.

IS2

IP6_TCP_UDP

369

0 (2)

1 (2)

IS2

IP6_OTHER

372

1 (2)

IS2

CUSTOM

363

2 (2)

1 (2)

IS2

SMAC_SIP4

Not used (0)

3 (2)

IS2

SMAC_SIP6

180

8 (4)

2 (2)

ES0

VID

Not used (0)

1 (1)

Table 70 •

Entry, Type, and Type-Group Parameters (continued)

VCAP

Entry Type

Entry Width

Subwords

Type Value

[width in ()]

Type-Group Value

[width in ()]

128

160

192

371

idx: 0

idx: 1

idx: 2

idx: 3

idx: 4

idx: 5

VCAP_ENTRY_DAT

371

VCAP_MASK_DAT

VCAP_TG_DAT

Entry Data

Mask data

224

256

288

320

352

idx: 6

idx: 7

idx: 8

idx: 9

idx: 10

idx: 11

384

128

160

192

idx: 0

idx: 1

idx: 2

idx: 3

idx: 4

idx: 5

224

256

288

320

352

idx: 6

idx: 7

idx: 8

idx: 9

idx: 10

idx: 11

384

idx: 0

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