E F E c o n f i g u r a t i o n

Register hash table

The MAC receiver provides the station address logic (SAL) with a 6-bit CRC value. This value points to a bit position in the 64-bit multicast hash table. A receive packet is accepted if the current frame is a multicast frame and the 6-bit CRC addresses a bit in the hash table that is set to 1. Otherwise, the packet is rejected.

The 64-bit address value is held in four registers, each containing 16 bits. The least significant bit of the first register corresponds to a CRC value of 0. The most significant bit of the last register corresponds to the CRC value of 63.

The multicast address bytes are loaded into the Station Address registers in Little Endian format.

Multicast hash table entries and bit definitions

Address: FF80 05D0

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HT1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

D31:16

N/A

Reserved

N/A

N/A

 

 

 

 

 

D15:00

R/W

HT1

0

CRC value 15–0

 

 

 

 

 

Table 81: HT1 bit definition

Address: FF80 05D4

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HT2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2 0 2

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

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Image 216
Digi NS7520 Register hash table, Multicast hash table entries and bit definitions, Address FF80 05D0, Address FF80 05D4