PM3350-SW datasheet(92/224 Pages) PMC

92 / 224 page

ELAN 8X10

PM3350 ELAN 8 X10

DATA SHEET

PMC-970109

ISSUE 3

8 PORT ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND PMC-SIERRA, INC. CUSTOMERS ONLY

24 23

Unused

Pointer to bucket/tag (NULL if none)

...

Unused

Pointer to bucket/tag (NULL if none)

Unused

Pointer to bucket/tag (NULL if none)

4N+4

Unused

Pointer to bucket/tag (NULL if none)

4N+8

Unused

Pointer to bucket/tag (NULL if none)

4N+12

Unused

Pointer to bucket/tag (NULL if none)

...

The hash pointer array occupies the locations in memory as described by the address

map given previously. Initially, all the pointers in the array are set to zero (NULL),

indicating that no MAC address is present in the hash table. As MAC addresses are

learned (or statically created), the hash buckets or forwarding tags corresponding to

these addresses are inserted into the hash table, and the relevant pointers in the array

are updated to point to the linked-lists of hash buckets and/or forwarding tags. Note that

newly learned addresses are always placed at the head of any linked-list thus created.

The size of the hash array, which determines the probability of collisions (i.e., the

probability that multiple MAC addresses will be associated with a single hash pointer

array index, leading to the need for traversing a linked-list), is a configurable parameter

that may be set at initialization.

The contents of the hash array are never cached by the Switch Processor in its data

cache; thus the hash array may be read via the PCI bus interface without data

consistency issues.

PM3350-SW Datasheet(PDF) 92 Page - PMC-Sierra, Inc