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IGMP V3 3
IGMPv2 SSM mapping
The PIM-SSM feature requires all IGMP hosts to send IGMPv3 reports. Where you have an IGMPv2
host, this can create a compatibility problem. In particular, the reports from an IGMPv2 host
contain a Group Multicast Address but do not contain source addresses. The IGMPv3 reports
contain both the Group Multicast Address and one or more source addresses. This feature converts
IGMPv2 reports into IGMPv3 reports through use of the ip igmp ssm-map commands and a
properly configured ACL.
The ACL used with this feature filters for the Group Multicast Address. The ACL is then associated
with one or more source addresses using the ip igmp ssm-map command. When the ip igmp
ssm-map enable command is configured, IGMPv3 reports are sent for IGMPv2 hosts.
The following sections describe how to configure the ACL and the ip igmp ssm-map commands to
use the IGMPv2 SSM mapping feature:
• Configuring an ACL for IGMPv2 SSM mapping
• Configuring the IGMPv2 SSM Mapping Commands
NOTE
IGMPv2 SSM Mapping is not supported for IGMP static groups.
Configuring an ACL for IGMPv2 SSM mapping
You can use either a standard or extended ACL to identify the group multicast address you want to
add source addresses to when creating a IGMPv3 report.
For standard ACLs, you must create an ACL with a permit clause and the ip-source-address variable
must contain the group multicast address. This can be configured directly with a subnet mask or
with the host keyword in which case a subnet mask of all zeros (0.0.0.0) is implied.
In the following example, access-list 20 is configured for the group multicast address: 224.1.1.0
with a subnet mask of 0.0.0.255.
Brocade(config)# access-list 20 permit 224.1.1.0 0.0.0.225
In the following example, access-list 20 is configured for the group multicast address: 239.1.1.1 by
including the host keyword.
Brocade(config)# access-list 20 host 239.1.1.1
For extended ACLs, the source address variable must contain either 000 or the any keyword.
Additionally, the extended ACL must be configured with a permit clause and the host keyword. This
can be configured directly with a subnet mask or with the host keyword in which case a subnet
mask of all zeros (0.0.0.0) is implied.
The ip-destination-address variable must contain the group multicast address.
In the following example, access-list 100 is configured for the group multicast address: 232.1.1.1
with a subnet mask of 0.0.0.255.
Brocade(config)# access-list 20 permit 224.1.1.0 0.0.0.225
In the following example, access-list 100 is configured for the group multicast address: 232.1.1.1.
Brocade(config)# access-list 100 permit any host 232.1.1.1
FastIron Ethernet Switch IP Multicast Configuration Guide 149
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