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12-2
Cisco ASDM User Guide
OL-16647-01
Chapter 12 Configuring Multicast Routing
IGMP
For More Information
Configuring Multicast Routing, page 12-1
IGMP, page 12-2
Multicast Route, page 12-7
MBoundary, page 12-9
MForwarding, page 12-11
PIM, page 12-11
IGMP
IP hosts use IGMP to report their group memberships to directly connected multicast routers. IGMP uses
group address (Class D IP addresses). Host group addresses can be in the range 224.0.0.0 to
239.255.255.255. The address 224.0.0.0 is never assigned to any group. The address 224.0.0.1 is
assigned to all systems on a subnet. The address 224.0.0.2 is assigned to all routers on a subnet.
For more information about configuring IGMP on the security appliance, see the following:
• Access Group
• Join Group
• Protocol
• Static Group
Access Group
Access groups control the multicast groups that are allowed on an interface.
Fields
• Access Groups—Displays the access groups defined for each interface.
The table entries are processed from the top down. Place more specific entries near the top of the
table and more generic entries further down. For example, place an access group entry that permits
a specific multicast group near the top of the table and an access group entry below that denies a
range of multicast groups, including the group in the permit rule. The group is permitted because
the permit rule is enforced before the deny rule.
Double-clicking an entry in the table opens the Add/Edit Access Group dialog box for the selected
entry.
–
Interface—Displays the interface the access group is associated with.
–
Action—Displays “Permit” if the multicast group address is permitted by the access rule.
Displays “Deny” if the multicast group address is denied by the access rule.
–
Multicast Group Address—Displays the multicast group address that the access rule applies to.
–
Netmask—Displays the network mask for the multicast group address.
• Insert Before—Opens the Add/Edit Access Group dialog box. Use this button to add a new access
group entry before the selected entry in the table.
• Insert After—Opens the Add/Edit Access Group dialog box. Use this button to add a new access
group entry after the selected entry in the table.