Administrator Guide

ip multicast-limit
The range if from 1 to 16000.
The default is 4000.
NOTE: The IN-L3-McastFib CAM partition is used to store multicast routes and is a separate hardware limit that exists
per port-pipe. Any software-configured limit may supersede by this hardware space limitation. The opposite is also true,
the CAM partition might not be exhausted at the time the system-wide route limit the ip multicast-limit command
sets is reached.
Preventing a Host from Joining a Group
You can prevent a host from joining a particular group by blocking specific IGMP reports. Create an extended access list containing the
permissible source-group pairs.
NOTE: For rules in IGMP access lists, source is the multicast source, not the source of the IGMP packet. For IGMPv2,
use the keyword any for source (as shown in the following example), because IGMPv2 hosts do not know in advance
who the source is for the group in which they are interested.
To apply the access list, use the following command.
• Apply the access list.
INTERFACE mode
ip igmp access-group access-list-name
Dell Networking OS Behavior: Do not enter the ip igmp access-group command before creating the access-list. If you do, after
entering your first deny rule, the system clears multicast routing table and re-learns all groups, even those not covered by the rules in the
access-list, because there is an implicit deny all rule at the end of all access-lists. Therefore, configuring an IGMP join request filter in this
order might result in data loss. If you must enter the ip igmp access-group command before creating the access-list, prevent the
system from clearing the routing table by entering a permit any rule with high sequence number before you enter any other rules.
In the following example, virtual local area network (VLAN) 400 is configured with an access list to permit only IGMP reports for group
239.0.0.1. Though Receiver 2 sends a membership report for groups 239.0.0.1 and 239.0.0.2, a multicast routing table entry is created only
for group 239.0.0.1. VLAN 300 has no access list limiting Receiver 1, so both IGMP reports are accepted, and two corresponding entries
are created in the routing table.
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Multicast Features