KSZ8993M-EVAL Micrel Inc, KSZ8993M-EVAL Datasheet - Page 34

• Manufacturer Part Number: KSZ8993M-EVAL
• Description: KSZ8993M Evaluation Board - For Experimental Use Only
• Manufacturer: Micrel Inc

Specifications of KSZ8993M-EVAL

• Lead Free Status / RoHS Status: Supplier Unconfirmed

SMI register access is the same as the MIIM register access, except for the register access requirements
presented in this section.
Advanced Switch Functions
Spanning Tree Support
To support spanning tree, port 3 is the designated port for the processor.
The other ports (port 1 and port 2) can be configured in one of the five spanning tree states via “transmit enable”,
“receive enable” and “learning disable” register settings in registers 18 and 34 for ports 1 and 2, respectively. The
following description shows the port setting and software actions taken for each of the five spanning tree states.
Disable state:
Blocking state:
Listening state:
Learning state:
Micrel, Inc.
October 2008
Port setting:
Software action:
Port setting:
Software action:
Port setting:
Software action:
Port setting:
Registers are 8 data bits wide. For read operation, data bits [15:8] are read back as 0’s. For write
operation, data bits [15:8] are not defined, and hence can be set to either 0’s or 1’s.
“transmit enable = 0, receive enable = 0, learning disable =1”
“transmit enable = 0, receive enable = 0, learning disable =1”
“transmit enable = 0, receive enable = 0, learning disable =1”
“transmit enable = 0, receive enable = 0, learning disable = 0”
The processor should not send any packets to the port. The switch may still send specific packets
to the processor (packets that match some entries in the “static MAC table” with “overriding bit”
set) and the processor should discard those packets. Note: processor is connected to port 3 via
MII interface. Address learning is disabled on the port in this state.
The processor should not send any packets to the port(s) in this state. The processor should
program the “Static MAC table” with the entries that it needs to receive (e.g. BPDU packets). The
“overriding” bit should also be set so that the switch will forward those specific packets to the
processor. Address learning is disabled on the port in this state.
The processor should program the “Static MAC table” with the entries that it needs to receive
(e.g., BPDU packets). The “overriding” bit should be set so that the switch will forward those
specific packets to the processor. The processor may send packets to the port(s) in this state,
see “Special Tagging Mode” for details. Address learning is disabled on the port in this state.
The port should not forward or receive any packets.
Learning is disabled.
Only packets to the processor are forwarded.
Learning is disabled.
Only packets to and from the processor are forwarded.
Learning is disabled.
Only packets to and from the processor are forwarded.
Learning is enabled.
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KSZ8993M/ML