Chapter 24 Multicast
GS2220 Series User’s Guide
230
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.
Normal Leave Enter an IGMP normal leave timeout value (from 200 to 6348800) in miliseconds. Select this
option to have the Switch use this timeout to update the forwarding table for the port.
In normal leave mode, when the Switch receives an IGMP leave message from a host on a
port, it forwards the message to the multicast router. The multicast router then sends out an
IGMP Group-Specific Query (GSQ) message to determine whether other hosts connected to
the port should remain in the specific multicast group. The Switch forwards the query message
to all hosts connected to the port and waits for IGMP reports from hosts to update the
forwarding table.
This defines how many seconds the Switch waits for an IGMP report before removing an IGMP
snooping membership entry when an IGMP leave message is received on this port from a
host.
Fast Leave Enter an IGMP fast leave timeout value (from 200 to 6348800) in miliseconds. Select this option
to have the Switch use this timeout to update the forwarding table for the port.
In fast leave mode, right after receiving an IGMP leave message from a host on a port, the
Switch itself sends out an IGMP Group-Specific Query (GSQ) message to determine whether
other hosts connected to the port should remain in the specific multicast group. This helps
speed up the leave process.
This defines how many seconds the Switch waits for an IGMP report before removing an IGMP
snooping membership entry when an IGMP leave message is received on this port from a
host.
Group Limited Select this option to limit the number of multicast groups this port is allowed to join.
Max Group Num. Enter the number of multicast groups this port is allowed to join. Once a port is registered in the
specified number of multicast groups, any new IGMP join report frames is dropped on this
port.
Throttling IGMP throttling controls how the Switch deals with the IGMP reports when the maximum
number of the IGMP groups a port can join is reached.
Select De ny to drop any new IGMP join report received on this port until an existing multicast
forwarding table entry is aged out.
Select Re pla c e to replace an existing entry in the multicast forwarding table with the new
IGMP reports received on this port.
Table 98 Advanced Application > Multicast > IPv4 Multicast > IGMP Snooping (continued)
LABEL DESC RIPTIO N
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