MDS212 Datasheet, PDF (53/111 Pages) Zarlink Semiconductor Inc – 12-Port 10/100Mbps Ethernet Switch

MDS212
14.2.4 MDS212 Data Structures For VLAN Implementation
63
0
FDB
Frame Data Buffers
External RAM
Transmission queues
CPU/HISC Mailing List
Data Sheet
FDB block must start from 0
Programmable Size
Programmable Size
VLAN ID Table
(4k entry, 8B/entry)
MAX
1/2MV, 1MB,
or 2MB
VLAN MAC Table
(2k entry, 256/128/64 bit)
Byte Byte Byte Byte Byte Byte Byte Byte
7
6
5
4
3
2
1
0
32KB
16, 32 or 64KB
(up to the number of supported VLAN)
Figure 18 - Data Structure Diagram
14.2.4.1 VLAN ID Table
The VLAN ID Table is used by Search Engine for unicast frames. The base address of this table is specified by
VIDB subfield in BIT[5:0] of VTBP register. The contents of this table are set up by the MDS212’s microcode
through the command of CPU software at the time of VLAN creation and deletion. The VLAN ID Table covers the
entire 4K VLAN ID space, and is used by the Search Engine to map the VLAN ID into an internal VLAN Index. It
also includes port membership and port tagging information for each VLAN. Each VLAN ID entry is 8 bytes long,
and the total size of the VLAN ID Table is 32KB. The VLAN ID table must be located at the 32K boundary.
Byte 31 30 29 28 27 26 25 24 23 22 21 _{20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3} 2 1 0
0
Index[3:0]
4
Index[7:4]
Bit[1:0] P0
Bit [0]
Bit [1]
Bit[3:2] P1
....
Bit [26]
Bit [27]
Bit [31:28]
CV
P11 P10 P9 P8
P23
VLAN Status for Port 0
S
T
VLAN status for Port 1
P7 P6 P5 P4 P3 P2 P1 T S
P13 P12
This port is a member of this VLAN
Tagout
V
VLAN is Valid
C
CPU is a member of this VLAN
1st byte: VLAN Index [3:0], 2nd byte: VLAN Index [7:4]
Figure 19 - VLAN ID Table
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