MDS212 Datasheet, PDF (28/111 Pages) Zarlink Semiconductor Inc – 12-Port 10/100Mbps Ethernet Switch

MDS212
Data Sheet
Description
Frame Data Buffer
(FDB)
Transmission
Queue
HISC Mailing List
Unit Size
1.5 Kbytes
Unit Count
Total Size
256 to 1K 384 K bytes to 1.5M bytes
4 bytes x 128K
to 4 bytes x 1K
48 (4 level
priority)
12 (1 level
priority)
32 Bytes to
128 to 1K
64Bytes
(Programmable)
24 Kbytes to 192Kbytes (at
4 level priority)
4K bytes to
32 Kbytes
(at 32 Bytes each)
Reference by
FE
FE
HISC & SE
Note: FE = Frame Engine, SE = Search Engine
In unmanaged mode, the system does not support VLAN features. Thus, VLAN related tables are not required.
Table 3 - Frame Buffer Memory Usage for Unmanaged Mode
5.2.1 Memory Allocation Of A Managed System
In a managed system, the Frame Buffer Memory is partitioned into five segments: Frame Data Buffers (FDBs),
Transmission Queues, Mailing Lists, VLAN, and MCT VLAN Association Tables.
5.2.1.1 Frame Data Buffers
The Frame Data Buffers (FDBs) accommodate the incoming data frames and partition them into data blocks, where
each block occupies 1.5K bytes. The number of data blocks in a FDB is configured by setting the value in the
register FCBSL[9:0]. Since MDS212 supports up to 2M Bytes memory, the maximum number of data blocks is 1K.
Note: The FDB must start at location 0.
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Zarlink Semiconductor Inc.