Datasheet
2017 Microchip Technology Inc. DS00002335B-page 29
KSZ8863MLL/FLL/RLL
3.8 IGMP Support
For Internet Group Management Protocol (IGMP) support in layer 2, KSZ8863MLL/FLL/RLL provides two components:
3.8.1 IGMP SNOOPING
KSZ8863MLL/FLL/RLL traps IGMP packets and forwards them only to the processor (port 3). The IGMP packets are
identified as IP packets (either Ethernet IP packets, or IEEE 802.3 SNAP IP packets) with IP version = 0x4 and protocol
version number = 0x2.
3.8.2 IGMP SEND BACK TO THE SUBSCRIBED PORT
Once the host responds to the received IGMP packet, the host should knows the original IGMP ingress port and send
back the IGMP packet to this port only. Otherwise this IGMP packet is broadcasted to all ports to downgrade the perfor-
mance.
Enabling the tail tag mode, the host will know the IGMP packet received port from tail tag bits [0] and can send back the
response IGMP packet to this subscribed port by setting the bits [1,0] in the tail tag. Enable “Tail tag mode” by setting
register 3 bit 6. The tail tag is removed automatically when the IGMP packet is sent out from the subscribed port.
3.9 Port Mirroring Support
KSZ8863MLL/FLL/RLL supports “Port Mirroring” as follows:
• “Receive only” mirror on a port
- All packets received on the port are mirrored on the sniffer port. For example, port 1 is programmed as the
“receive sniff” and port 3 is programmed as the “sniffer port.” A packet received on port 1 is destined to port 2
after the internal lookup. KSZ8863MLL/FLL/RLL forwards the packet to both port 2 and port 3. KSZ8863MLL/
FLL/RLL can also optionally forward “bad” received packets to the “sniffer port.”
• “Transmit only” mirror on a port
- All packets transmitted on the port are mirrored on the sniffer port. For example, port 1 is programmed as the
“transmit sniff” and port 3 is programmed as the “sniffer port.” A packet received on port 2 is destined to port 1
after the internal lookup. KSZ8863MLL/FLL/RLL forwards the packet to both port 1 and port 3.
• “Receive and transmit” mirror on two ports
- All packets received on port A and transmitted on port B are mirrored on the sniffer port. To turn on the “AND”
feature, set register 5 bit [0] to ‘1’. For example, port 1 is programmed as the “receive sniff,” port 2 is pro-
grammed as the “transmit sniff,” and port 3 is programmed as the “sniffer port.” A packet received on port 1 is
destined to port 2 after the internal lookup. KSZ8863MLL/FLL/RLL forwards the packet to both port 2 and port
3.
Multiple ports can be selected as the “receive sniff” or the “transmit sniff.” In addition, any port can be selected as the
“sniffer port.” All these per-port features can be selected through registers 17, 33, and 49 for ports 1, 2, and 3, respec-
tively.
3.10 Rate Limiting Support
KSZ8863MLL/FLL/RLL provides a fine resolution hardware rate limiting from 64 kbps to 99 Mbps. The rate step is
64 kbps when the rate range is from 64 kbps to 960 kbps, and 1 Mbps for 1 Mbps to 100 Mbps (100BT) or to 10 Mbps
(10BT) (refer to Data Rate Limit Table). The rate limit is independent on the “receive side” and on the “transmit side” on
a per-port basis. For 10BASE-T, a rate setting above 10 Mbps means the rate is not limited. On the receive side, the
data receive rate for each priority at each port can be limited by setting up Ingress Rate Control Registers. On the trans-
mit side, the data transmit rate for each priority queue at each port can be limited by setting up Egress Rate Control
Registers. The size of each frame has options to include a minimum IFG (Inter Frame Gap) or a Preamble byte, in addi-
tion to the data field (from packet DA to FCS).
For ingress rate limiting, KSZ8863MLL/FLL/RLL provides options to selectively choose frames from all types, multicast,
broadcast, and flooded unicast frames. KSZ8863MLL/FLL/RLL counts the data rate from those selected type of frames.
Packets are dropped at the ingress port when the data rate exceeds the specified rate limit.
For egress rate limiting, the Leaky Bucket algorithm is applied to each output priority queue for shaping output traffic.
Inter frame gap is stretched on a per-frame base to generate smooth, non-burst egress traffic. The throughput of each
output priority queue is limited by the egress rate specified.