Chapter 61 Switching
GS2220 Series User’s Guide
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Report Proxy Select this option to allow the Switch to act as the IGMP report proxy and leave proxy. It will
report group changes to a connected multicast router.
The Switch not only checks IGMP packets between multicast routers or switches and multicast
hosts to learn the multicast group membership, but also replaces the source MAC address in
an IGMP v1/v2 report with its own MAC address before forwarding to the multicast router or
switch. When the Switch receives more than one IGMP v1/v2 join report that requests to join
the same multicast group, it only sends a new join report with its MAC address. This helps
reduce the number of multicast join reports passed to the multicast router or switch.
The Switch sends a leave message with its MAC address to the multicast router or switch only
when it receives the leave message from the last host in a multicast group.
IGMP Filtering
Active
Select O n to enable IGMP filtering
to control which IGMP groups a subscriber on a port can
join.
If you enable IGMP filtering, you must create and assign IGMP filtering profiles for the ports that
you want to allow to join multicast groups.
IGMP Snooping
Smart Forward
Active
Select O n to enable sending of multicast frame to querier port and IGMP subscriber groups.
Otherwise, the querier port forwards the frames only when it receives a join report and it
belongs to the IGMP group.
Unknown Multicast
Frame
Specify the action to perform when the Switch receives an unknown multicast frame.
•Select Dro p to discard the frames.
•Select Flo oding to send the frames to all ports.
•Select Dro p o n VLA N and enter the VLAN ID numbers to discard the frames on the
specified VLANs. Use a dash to specify consecutive VLANs and a comma (no spaces) to
specify non-consecutive VLANs. For example, 51–53 includes 51, 52 and 53, but 51,53 does
not include 52.
Unknown Multicast
Frame to Querier
Port
Specify the action to perform when Unknown Multic a st Fra m e is set to Dro p.
•Select Dro p to discard the frames.
•Select Forwa rding to send the frames to all querier ports.
•Select Forwa rding o n VLAN and enter the VLAN ID numbers to send the frames to the ports
which are used as an IGMP query port on the specified VLANs. Use a dash to specify
consecutive VLANs and a comma (no spaces) to specify non-consecutive VLANs. For
example, 51–53 includes 51, 52 and 53, but 51,53 does not include 52.
Reserved Multicast
Group
The IP address range of 224.0.0.0 to 224.0.0.255 are reserved for multicasting on the local
network only. For example, 224.0.0.1 is for all hosts on a local network segment and 224.0.0.9 is
used to send RIP routing information to all RIP v2 routers on the same network segment. A
multicast router will not forward a packet with the destination IP address within this range to
other networks. See the IANA web site for more information.
The layer-2 multicast MAC addresses used by Cisco layer-2 protocols, 01:00:0C:CC:CC:CC
and 01:00:0C:CC:CC:CD, are also included in this group.
Specify the action to perform when the Switch receives a frame with a reserved multicast
address.
•Select Dro p to discard the frames.
•Select Flo oding to send the frames to all ports.
Port This field displays the port number.
* Settings in this row apply to all ports.
Use this row only if you want to make some settings the same for all ports. Use this row first to set
the common settings and then make adjustments on a port-by-port basis.
Changes in this row are copied to all the ports as soon as you make them.
Immed. Leave Select this option to set the Switch to remove this port from the multicast tree when an IGMP
version 2 leave message is received on this port.
Select this option if there is only one host connected to this port.
Table 258 Switching > Multicast > IGMP Snooping (continued)
LABEL DESC RIPTIO N
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