KSZ8795CLX
TABLE 4-3:
Address
GLOBAL REGISTERS (CONTINUED)
Name
Description
Mode
Default
Register 4 (0x04): Global Control 2
7
Unicast Port-VLAN
Mismatch Discard
This feature is used for port VLAN (described in
Port Control 1 Register).
R/W
1
1 = All packets cannot cross VLAN boundary.
0 = Unicast packets (excluding unknown/multicast/
broadcast) can cross VLAN boundary.
Note: When mirroring is enabled, the single-desti-
nation packets will be dropped if it’s mirrored to
another port.
6
Multicast Storm
Protection Disable
1 = “Broadcast Storm Protection” does not include
multicast packets. Only DA = FFFFFFFFFFFF
packets will be regulated.
R/W
1
0 = “Broadcast Storm Protection” includes
DA = FFFFFFFFFFFF and DA[40] = 1 packet.
5
4
Back
Pressure Mode
1 = Carrier-sense-based back pressure is selected.
0 = Collision-based back pressure is selected.
R/W
R/W
1
1
Flow Control and Back 1 = Fair mode is selected. In this mode, if a flow
Pressure Fair Mode
control port and a non-flow control port talk to the
same destination port, then packets from the non-
flow control port may be dropped. This is to prevent
the flow control port from being flow controlled for
an extended period of time.
0 = In this mode, if a flow control port and a non-
flow control port talk to the same destination port,
the flow control port will be flow controlled. This
may not be “fair” to the flow control port.
3
No
1 = The switch will not drop packets when 16 or
R/W
0
Excessive Collision Drop more collisions occur.
0 = The switch will drop packets when 16 or more
collisions occur.
2
1
Reserved
N/A Don’t change.
RO
0
0
Legal
Maximum Packet
Size Check Disable
1 = Enables acceptance of packet sizes up to 1536
bytes (inclusive).
0 = 1522 bytes for tagged packets (not including
packets with STPID from CPU to Ports 1-4), 1518
bytes for untagged packets. Any packets larger
than the specified value will be dropped.
R/W
0
Reserved
N/A
RO
0
0
Register 5 (0x05): Global Control 3
7
802.1q VLAN Enable
1 = 802.1q VLAN mode is turned on. VLAN table
needs to be set up before the operation.
0 = 802.1q VLAN is disabled.
R/W
6
IGMP Snoop Enable on 1 = IGMP Snoop enabled. All the IGMP packets will
Switch Port 5 SW5-GMII/ be forwarded to the processor via Switch Port 5
R/W
RO
0
RGMII/MII/RMII
Interface
GMII/RGMII/MII/RMII interface.
0 = IGMP Snoop disabled.
5 1
Reserved
N/A Don’t change.
00000
DS00002112A-page 50
2016 Microchip Technology Inc.
MICREL [ MICREL SEMICONDUCTOR ]
