ACD82224 Datasheet, PDF (35/77 Pages) List of Unclassifed Manufacturers – 24 Ports 10/100 Fast Ethernet Switch

nFWD register (register 20)
The nFWD register defines the forwarding mode of each port. Under forwarding mode, a port
can forward all frames. Under block-and-listen mode, a port will not forward regular frames,
except BPDU frames. If the spanning tree algorithm discovers redundant links, the control CPU
will allow only one link remaining in forwarding mode and force the other links into block-and-
listen mode. Setting the associated bit in this register will put the port into block-and-listen mode.
Table-7.20 describes all the bits of this register.
Table-7.20: nFWD Register
Bit
Description
[0:23]
0 – Port X in forwarding state.
1 – Port X in block-and-listen state.
Default
0
nBP register (register 21)
The nBP register defines backpressure flow control capability for each port. Table-7.21 describes
all the bits of this register.
Table-7.21: nBP Register
Bit
Description
[0:23]
0 – Port X back-pressure scheme enabled
1 – Port X back pressure scheme disabled
Default
0
nPORT register (register 22)
The nPORT register is used to isolate ports from the network. Setting the associated bit in this
register will stop a port from either receiving or transmitting any frame. Table-7.22 describes all
the bits of this register. But, the source MAC address is still learned by ARL unless ARL
nLearnReg is set for the specific port.
Table-7.22: nPORT Register
Bit
Description
[0:23]
0 – Port X enabled
1 – Port X disabled
Default
0
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