KSZ8893FQL-FX Micrel Inc, KSZ8893FQL-FX Datasheet - Page 46

• Manufacturer Part Number: KSZ8893FQL-FX
• Description: 2+1 Port 10/100 Switch W/Tranceivers & Frame Buffers, ( )
• Manufacturer: Micrel Inc

Specifications of KSZ8893FQL-FX

• Controller Type: Ethernet Switch Controller
• Interface: MII, RMII, SNI
• Voltage - Supply: 3.1 V ~ 3.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• Number Of Primary Switch Ports: 3
• Internal Memory Buffer Size: 32
• Operating Supply Voltage (typ): 3.3V
• Fiber Support: Yes
• Integrated Led Drivers: Yes
• Power Supply Type: Analog/Digital
• Package Type: PQFP
• Vlan Support: Yes
• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Pin Count: 128
• Mounting: Surface Mount
• Jtag Support: No
• Operating Temperature Classification: Commercial
• Data Rate: 1000Mbps
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 576-1603 - EVAL KIT EXPERIMENTAL KSZ8893MQL
• Current - Supply: -
• Lead Free Status / RoHS Status: Compliant, Lead free / RoHS Compliant
• Other names: 576-3273

Micrel, Inc.
KSZ8893FQL
QoS Priority Support
The KSZ8893FQL provides Quality of Service (QoS) for applications such as VoIP and video conferencing. Offering
four priority queues per port, the per-port transmit queue can be split into four priority queues: Queue 3 is the highest
priority queue and Queue 0 is the lowest priority queue. Bit [0] of registers 16, 32 and 48 is used to enable split transmit
queues for ports 1, 2 and 3, respectively. If a port's transmit queue is not split, high priority and low priority packets
have equal priority in the transmit queue.
There is an additional option to either always deliver high priority packets first or use weighted fair queuing for the four
priority queues. This global option is set and explained in bit [3] of register 5.
Port-Based Priority
With port-based priority, each ingress port is individually classified as a high priority receiving port. All packets received
at the high priority receiving port are marked as high priority and are sent to the high-priority transmit queue if the
corresponding transmit queue is split. Bits [4:3] of registers 16, 32 and 48 are used to enable port-based priority for
ports 1, 2 and 3, respectively.
802.1p-Based Priority
For 802.1p-based priority, the KSZ8893FQL examines the ingress (incoming) packets to determine whether they are
tagged. If tagged, the 3-bit priority field in the VLAN tag is retrieved and compared against the “priority mapping” value,
as specified by the registers 12 and 13. The “priority mapping” value is programmable.
The following figure illustrates how the 802.1p priority field is embedded in the 802.1Q VLAN tag.
Figure 9. 802.1p Priority Field Format
802.1p-based priority is enabled by bit [5] of registers 16, 32 and 48 for ports 1, 2 and 3, respectively.
The KSZ8893FQL provides the option to insert or remove the priority tagged frame's header at each individual egress
port. This header, consisting of the 2 bytes VLAN Protocol ID (VPID) and the 2-byte Tag Control Information field (TCI),
is also referred to as the IEEE 802.1Q VLAN tag.
Tag Insertion is enabled by bit [2] of registers 16, 32 and 48 for ports 1, 2 and 3, respectively. At the egress port,
untagged packets are tagged with the ingress port’s default tag. The default tags are programmed in register sets
{19,20}, {35,36} and {51,52} for ports 1, 2 and 3, respectively. The KSZ8893FQL will not add tags to already tagged
packets.
Tag Removal is enabled by bit [1] of registers 16, 32 and 48 for ports 1, 2 and 3, respectively. At the egress port,
tagged packets will have their 802.1Q VLAN Tags removed. The KSZ8893FQL will not modify untagged packets.
The CRC is recalculated for both tag insertion and tag removal.
802.1p Priority Field Re-mapping is a QoS feature that allows the KSZ8893FQL to set the “User Priority Ceiling” at
any ingress port. If the ingress packet’s priority field has a higher priority value than the default tag’s priority field of the
ingress port, the packet’s priority field is replaced with the default tag’s priority field. The “User Priority Ceiling” is
enabled by bit [3] of registers 17, 33 and 49 for ports 1, 2 and 3, respectively.
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October 2007
M9999-101607-1.3