KSZ8893M Datasheet, PDF (64/116 Pages) Micrel Semiconductor – Integrated 3-Port 10/100 Managed Switch with PHYs

Micrel, Inc.
KSZ8893MQL/MBL
Register 4 (0x04): Global Control 2 (continued)
Bit
Name
R/W Description
Default
4
Flow Control R/W = 1, fair mode is selected. In this mode, if a flow
1
and Back
control port and a non-flow control port talk to the
Pressure Fair
same destination port, packets from the non-flow
Mode
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 Excessive R/W = 1, the switch will not drop packets when 16 or more 0
Collision Drop
collisions occur.
= 0, the switch will drop packets when 16 or more
collisions occur.
2
Huge Packet R/W = 1, will accept packet sizes up to 1916 bytes
0
Support
(inclusive). This bit setting will override setting from
bit 1 of this register.
= 0, the max packet size will be determined by bit 1 of
this register.
1
Legal
R/W = 0, will accept packet sizes up to 1536 bytes
SMRXD0
Maximum
(inclusive).
(pin 85)
Packet Size
Check Enable
= 1, 1522 bytes for tagged packets, 1518 bytes for
untagged packets. Any packets larger than the
value
during reset
specified value will be dropped.
0
Priority Buffer R/W = 1, each port is pre-allocated 48 buffers for high
1
Reserve
priority (q3, q2, and q1) packets. This selection is
effective only when the multiple queue feature is
turned on. It is recommended to enable this bit for
multiple queue.
= 0, no reserved buffers for high priority packets.
Each port is pre-allocated 48 buffers for all priority
packets (q3, q2,q1, and q0).
Register 5 (0x05): Global Control 3
Bit
Name
R/W Description
7
802.1Q VLAN R/W = 1, 802.1Q VLAN mode is turned on. VLAN table
Enable
needs to set up before the operation.
= 0, 802.1Q VLAN is disabled.
6
IGMP Snoop R/W =1, IGMP snoop is enabled. All IGMP packets will be
Enable on
forwarded to the Switch MII port.
Switch MII
Interface
=0, IGMP snoop is disabled.
5
IPv6 MLD
R/W IPv6 MLD snooping
Snooping
Enable
1 = enable
0 = disable
4
IPv6 MLD
R/W IPv6 MLD snooping option
Snooping
Option
1 = enable
0 = disable
Default
0
0
0
0
February 2010
64
M9999-021110-1.6