MDS213 Datasheet, PDF (32/120 Pages) Zarlink Semiconductor Inc – 12-Port 10/100Mbps + 1Gbps Ethernet Switch

MDS213
Data Sheet
5.2.5 VLAN Table
The VLAN Table associates the ports to their respective VLANs, using the VLAN ID. The table contains 4K VLAN
entries, where each entry contains 8 bytes of information. The size of the VLAN Table is 32KB (4Kx8B). The base
address of the VLAN Table is specified by the VIDB in the VTBP bit [5:0].
Note: The VLAN Table must be located at the 32K boundary.
5.2.6 VLAN MAC Association Table
The VLAN MAC Table (VLAN MCT) associates each port's MAC address with its respective VLAN. The Table
comprises of 2048 entries, one entry per MAC address. Each VLAN MAC entry is mapped to each bit associated
with a VLAN specified by the VLAN Index. The size of the Table is defined by two bits in the VTBP register and
depends on the system configuration (e.g. the number of VLANs supported in the system). Each entry may consist
of 256, 128 or 64 bits (one bit per VLAN). The total size of the VLAN MAC Table may be 16, 32 or 64KB. The
VMACB field in the register VTBP specifies the base address.
Note: The VLAN MAC Table must be located at the 16K boundary.
5.2.7 Unmanaged System memory allocation
Since an unmanaged system does not support VLAN operation, the VLAN and VLAN MAC tables are not required.
Only the Frame Data Buffers, Transmission Queues, and HISC Mailing Lists are allocated in system memory.
63
FDB block
must start from 0
0
0
FDB
Frame Data Buffers
(1.5KB x # of frame buffers)
Transmission queues
(4x13 =52 queues)
(each entry = 1DW)
(#entry of Queue = 128 to 1K)
HISC Mailing List
(#entry = 128 to 1K)
(each mail entry=32 bytes
to 64 bytes)
Byte Byte Byte ByteByte ByteByte Byte
765 4321 0
Programmable Size
Programmable Size
MAX
1/2MB, 1MB or 2MB
Figure 6 - Memory Map of an Unmanaged System
5.3 The Frame Memory Interface
5.3.1 Local memory interface
Each frame within the MDS213 is allocated its own buffer memory. The primary function of the Frame Buffer
Memory is to provide a temporary buffering space for both received and transmitted frames, as well as frames
waiting in the transmission queue. The actual usage depends on the frame type to be transmitted, either unicast or
multicast and the relationship between the source and destination ports. The buffer memory also, contains other
control structures including stacks, queues, other control tables. The buffer memory may be configured for 128K,
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