KSZ9567R_V01 datasheet(41/233 Pages) MICROCHIP

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DS00002329E-page 41

KSZ9567R

4.4.10.1

“IGMP” Snooping

The device traps IGMP packets and forwards them only to the processor (host port). 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.

4.4.10.2

“Multicast Address Insertion” in the Static MAC Table

Once the multicast address is programmed in the Static Address Table or Address Lookup Table, the multicast session

is trimmed to the subscribed ports, instead of broadcasting to all ports.

So that the host processor knows which port the IGMP packet was received on, Tail Tagging Mode must be enabled.

4.4.11

IPV6 MLD SNOOPING

The device traps IPv6 Multicast Listener Discovery (MLD) packets and forwards them only to the processor (host port).

4.4.12

PORT MIRRORING

the device supports “port mirroring” comprehensively as:

• “Receive Only” Mirror-on-a-Port

• “Transmit Only” Mirror-on-a-Port

• “Receive and Transmit” Mirror-on-a-Port

4.4.12.1

“Receive Only” Mirror-on-a-Port

All the packets received on the port are mirrored on the sniffer port. For example, 1 is programmed to be “receive sniff”

and the host port is programmed to be the “sniffer”. A packet received on port 1 is destined to port 2 after the internal

lookup. The packet is forwarded to both port 2 and the host port. The device can optionally even forward “bad” received

packets to the “sniffer port”.

4.4.12.2

“Transmit Only” Mirror-on-a-Port

All the packets transmitted on the port are mirrored on the sniffer port. For example, port 1 is programmed to be “transmit

sniff” and the host port is programmed to be the “sniffer port”. A packet received on port 2 is destined to port 1 after the

internal lookup. The device forwards the packet to both port 1 and the host port.

4.4.12.3

“Receive and Transmit” Mirror-on-a-Port

All the packets received on port A and transmitted on port B are mirrored on the sniffer port. For example, port 1 is pro-

grammed to be “receive sniff”, port 2 is programmed to be “transmit sniff”, and the host port is programmed to be the

“sniffer port”. A packet received on port 1 is destined to port 2 after the internal lookup. The device forwards the packet

to both port 2 and the host port.

Multiple ports can be selected as “receive sniff” or “transmit sniff”. In addition, any port can be selected as the “sniffer

port”.

4.4.13

SCHEDULING AND RATE LIMITING

Each device port has two egress packet scheduling options, which can be applied when the port is configured for two

or four queues. Additionally, each port has ingress and egress rate limiter features.

4.4.13.1

Strict Priority Scheduling

When an egress port is configured as two or four queues, and strict priority scheduling is selected, each queue will take

absolute priority over all lower priority queues. If a packet is available to transmit from queue 3 (the highest priority

queue), then it will take priority for transmission over any packet that will also be available in any of the other queues.

A packet in queue 2 will be transmitted only if no packet is available in queue 3. Weighted round robin is an alternative

to strict priority scheduling.

4.4.13.2

Weighted Round Robin (WRR) Scheduling

WRR scheduling is an alternative to strict priority scheduling for egress queues. It is referred to as fair queuing because

it gives proportionally higher priority to the highest priority queue, but not absolute priority.

Note:

The port for which Tail Tagging Mode is enabled is the host port.

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