KSZ8995M Micrel Inc, KSZ8995M Datasheet - Page 29

• Manufacturer Part Number: KSZ8995M
• Description: IC SWITCH 10/100 5PORT 128PQFP
• Manufacturer: Micrel Inc

Specifications of KSZ8995M

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• Number Of Primary Switch Ports: 5
• Internal Memory Buffer Size: 64
• Operating Supply Voltage (typ): 1.8/2.5/3.3V
• Fiber Support: Yes
• Integrated Led Drivers: Yes
• Phy/transceiver Interface: MII/SNI
• Power Supply Type: Analog/Digital
• Package Type: PQFP
• Data Rate (typ): 10/100Mbps
• Vlan Support: Yes
• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Pin Count: 128
• Mounting: Surface Mount
• Jtag Support: No
• Operating Supply Voltage (max): 1.9/2.6/3.6V
• Operating Supply Voltage (min): 1.7/2.4/3V
• Operating Temperature Classification: Commercial
• Data Rate: 100Mbps
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 576-1607 - BOARD EVAL EXPERIMENT KSZ8995MA
• Lead Free Status / RoHS Status: Compliant, Lead free / RoHS Compliant
• Other names: 576-1038

Learning state: only packets to and from the processor are forwarded. Learning is enabled.
Port setting: “transmit enable = 0, receive enable = 0, learning disable = 0”
Software action: 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” section for details. Address learning is enabled on
the port in this state.
Forwarding state: packets are forwarded and received normally. Learning is enabled.
Port setting: “transmit enable = 1, receive enable = 1, learning disable = 0”
Software action: 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” section for details. Address learning is enabled on
the port in this state.
Special Tagging Mode
The special tagging mode is designed for spanning tree protocol IGMP snooping and is flexible for use in other applications.
The special tagging mode, similar to 802.1q, requires software to change network drivers to insert/modify/strip/interpret the
special tag. This mode is enabled by setting both register 11 bit 0 and register 80-bit 2.
The STPID will only be seen and used on the port 5 interface, which should be connected to a processor. Packets from the
processor to the switch should be tagged with STPID and the port mask defined as below:
“0000” normal tag, will use KS8995M internal look-up result. Normal packets should use this setting. If packets from the
processors do not have a tag, the KS8995M will treat them as normal packets and an internal look-up will be performed.
The KS8995M uses a non-zero “port mask” to bypass the look-up result and override any port setting, regardless of port states
(blocking, disable, listening, learning). The Table 5 shows the egress rules when dealing with STPID.
December 2003
KS8995M
802.1q Tag Format
TPID (tag protocol identifier, 0x8100) + TCI
“0001” packet to port 1 only
“0010” packet to port 2 only
“0100” packet to port 3 only
“1000” packet to port 4 only
“0011” packet broadcast to port 1 and port 2.
.....
“1111” packet broadcast to port 1, 2, 3 and 4.
Table 4. Special Tagging Mode Format
Special Tag Format
STPID (special tag identifier, 0x8100) + TCI 0x810 + 4 bit for “port mask”) + TCI
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Micrel