Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 399

Chapter 26 Configuring MLDv2 Snooping for IPv6 Multicast Traffic
When the switch snoops the MLDv2 report multicast by Host 1, the switch uses the information in the
MLDv2 report to create a forwarding-table entry, as shown in
of Host 1, the multicast router, and the switch.
Table 26-1
Destination MAC Address
0100.5exx.xxxx
0100.5e01.0203
The switch hardware can distinguish MLDv2 information packets from other packets for the multicast
group. The first entry in the table indicates that only MLDv2 packets should be sent to the CPU, which
prevents the switch from becoming overloaded with multicast frames. The second entry indicates that
frames addressed to the 0x0100.5E01.0203 multicast MAC address that are not MLDv2 packets
(!MLDv2) should be sent to the multicast router and to the host that has joined the group.
If another host (for example, Host 4) sends an unsolicited MLDv2 report for the same group
(Figure
as shown in
message is not flooded to other ports. Any known multicast traffic is forwarded to the group and not to
the switch.
Figure 26-2
Forwarding
Table 26-2
Destination MAC Address
0100.5exx.xxxx
0100.5e01.0203
OL-11439-03
MLDv2 Snooping Forwarding Table
Type of Packet
MLDv2
!MLDv2
26-2), the switch snoops that message and adds the port number of Host 4 to the forwarding table
Table 26-2. Because the forwarding table directs MLDv2 messages only to the switch, the
Second Host Joining a Multicast Group
Router A
1
PFC
CPU
0
table
2 3
Host 1 Host 2
Updated MLDv2 Snooping Forwarding Table
Type of Packet
MLDv2
!MLDv2
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
Table
Ports
0
1, 2
VLAN
4 5
Host 3 Host 4
Ports
0
1, 2, 5
Understanding How MLDv2 Snooping Works
26-1, that includes the port numbers
26-5