2.2.a Implement and troubleshoot IGMP

2.2.a [iv] IGMP filter

IGMP filtering allows users to configure filters on a Switch Virtual Interface (SVI), a per-port, or a per-port per-VLAN basis to control the propagation of IGMP traffic through the network. IGMP filtering provides the capability to manage IGMP snooping, which in turn controls the forwarding of multicast traffic. When an IGMP packet is received, IGMP filtering uses the filters configured by the user to determine whether the IGMP packet should be discarded or allowed to be processed by the existing IGMP snooping code. With a IGMP version 1 or version 2 packet , the entire packet is discarded. With a IGMPv3 packet, the packet is rewritten to remove message elements that were denied by the filters.

IGMP traffic filters control the access of a port to multicast traffic. Access can be restricted based on the following:

● Which multicast groups or channels can be joined on a port. Channels are joined by IGMPv3 hosts that specify both the group and the source of the multicast traffic.

● Maximum number of groups or channels allowed on a specific port or interface (regardless of the number of hosts requesting service).

● IGMP protocol versions (for example, disallow all IGMPv1 messages).

When you enter an IGMP filtering command, a user policy is applied to a Layer 3 SVI interface, a Layer 2 port, or a particular VLAN on a Layer 2 trunk port. The Layer 2 port may be an access port or a trunk port. The IGMP filtering features will work only if IGMP snooping is enabled (either on the interface or globally).

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 2062-2074).  . Kindle Edition.