KSZ8864RMNI MICREL [Micrel Semiconductor], KSZ8864RMNI Datasheet - Page 40

• Manufacturer Part Number: KSZ8864RMNI
• Description: Integrated 4-Port 10/100 Managed Switch with Two MACs MII or RMII Interfaces
• Manufacturer: MICREL [Micrel Semiconductor]

September 2011
IGMP Support
There are two parts involved to support the Internet Group Management Protocol (IGMP) in Layer 2. The first part is
IGMP snooping, the second part is this IGMP packet to be sent back to the subscribed port. Describe them as
follows.
Port Mirroring Support
KSZ8864RMN supports “port mirror” comprehensively as:
Multiple ports can be selected to be “rx sniffed” or “tx sniffed.” And any port can be selected to be the “sniffer port.”
All these per port features can be selected through Register 17.
VLAN Support
KSZ8864RMN supports 128 active VLANs and 4096 possible VIDs specified in IEEE 802.1q. The KSZ8864RMN
provides a 128-entry VLAN table, which correspond to 4096 possible VIDs and converts to FID (7 bits) for address
look-up maximum of 128 active VLANs. If a non-tagged or null-VID-tagged packet is received, the ingress port VID is
used for look-up when 802.1q is enabled by the global register 5 control 3 bit 7. In the VLAN mode, the look-up
process starts from VLAN table look-up to determine whether the VID is valid. If the VID is not valid, the packet will
be dropped and its address will not be learned. If the VID is valid, then FID is retrieved for further look-up by the
static MAC table or dynamic MAC table. FID+DA is used to determine the destination port. The followed table
describles the difference actions at different situstions of DA and FID+DA in the static MAC table and dynamic MAC
table after the VLAN table finish a look-up action. FID+SA is used for learning purposes. Table 6 also describles how
to learning in the dynamic MAC table when VLAN table has done a look-up and the static MAC table without a valid
entry.
IGMP Snooping
The KSZ8864RMN traps IGMP packets and forwards them only to the processor (Port 4 SW4-MII/RMII). 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. Set register 5 bit [6] to ‘1’ to enable IGMP snooping.
IGMP Send Back to the Subscribed Port
Once the host responds 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 will be broadcasted to all port to
downgrade the performance.
Enable the tail tag mode, the host will know the IGMP packet received port from tail tag bits [1:0] and can send
back the response IGMP packet to this subscribed port by setting the bits [3:1] in the tail tag. Enable “Tail tag
mode” by setting Register 12 bit 1.
“Receive Only” Mirror on a Port
All the packets received on the port will be mirrored on the sniffer port. For example, Port 1 is programmed to be
“rx sniff,” and Port 2 is programmed to be the “sniffer port.” A packet, received on Port 1, is destined to Port 3
after the internal look-up. The KSZ8864RMN will forward the packet to both Port 2 and Port 3. KSZ8864RMN can
optionally forward even “bad” received packets to Port 3.
“Transmit Only” Mirror on a Port
All the packets transmitted on the port will be mirrored on the sniffer port. For example, Port 1 is programmed to
be “tx sniff,” and Port 2 is programmed to be the “sniffer port.” A packet, received on any of the ports, is destined
to port 1 after the internal look-up. The KSZ8864RMN will forward the packet to both Ports 1 and 2.
“Receive and Transmit” Mirror on a Port
All the packets received on port A AND transmitted on port B will be mirrored on the sniffer port. To turn on the
“AND” feature, set Register 5 bit 0 to 1. For example, Port 1 is programmed to be “rx sniff and tx sniff,” and Port 2
is programmed to be the “sniffer port.” A packet, received and transmit on port 1. The KSZ8864RMN will monitor
port 1 packets on Port 2.
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