Specifications

Micrel, Inc.
KSZ8895MQ/RQ/FMQ
Global Registers (Continued)
Address Name Description Mode Default
3
Frame Length Field
Check
1, will check frame length field in the IEEE packets
If the actual length does not match, the packet will be
dropped (for L/T <1500) .
R/W 0
2 Aging Enable
1, Enable age function in the chip.
0, Disable aging function.
R/W
1
Pin LED[5][2]
strap option.
PD(0): Aging
disable.
PU(1): Aging
enable (default).
Note: LED[5][2]
has internal pull
up.
1 Fast age Enable 1 = Turn on fast age (800µs). R/W 0
0
Aggressive Back Off
Enable
1 = Enable more aggressive back-off algorithm in half
duplex mode to enhance performance. This is not an
IEEE standard.
R/W
0
Pin PMRXD0
strap option.
PD(0): Disable
aggressive back
off (default).
PU(1):
Aggressive back
off.
Note: PMRXD0
has internal pull
down.
Register 4 (0x04): Global Control 2
7
Unicast Port-VLAN
Mismatch Discard
This feature is used for port VLAN (described in
Register 17, Register 33...).
1, all packets can not cross VLAN boundary.
0, unicast packets (excluding unknown/
multicast/broadcast) can cross VLAN boundary.
R/W 1
6
Multicast Storm
Protection Disable
1, “Broadcast Storm Protection” does not include
multicast packets. Only DA = FFFFFFFFFFFF packets
will be regulated.
0, “Broadcast Storm Protection” includes
DA = FFFFFFFFFFFF and DA[40] = 1 packet.
R/W 1
5 Back Pressure Mode
1, carrier sense based backpressure is selected.
0, collision based backpressure is selected.
R/W 1
March 12, 2014
58
Revision 1.7