High Availability Features - Cisco ASR 9000 Series Configuration Manual

Implementing Layer-2 Multicast with IGMP Snooping
Implemented in a multicast network, IGMP snooping has the following attributes:
• In its basic form, it reduces bandwidth consumption by reducing multicast traffic that would otherwise
flood an entire VPLS bridge domain.
• With the use of some optional configurations, it provides security between bridge domains by filtering
the IGMP reports received from hosts on one bridge port and preventing leakage towards the hosts on
other bridge ports.
• Using optional configurations, reduces the traffic impact on upstream IP multicast routers by suppressing
IGMP membership reports (IGMPv2) or by acting as an IGMP proxy reporter (IGMPv3) to the upstream
IP multicast router.

High Availability Features

All high availability features apply to the IGMP snooping processes with no additional configuration beyond
enabling IGMP snooping. The following high availability features are supported:
• Process restarts
• RP Failover
• Stateful Switch-Over (SSO)
• Non-Stop Forwarding (NSF)—Forwarding continues unaffected while the control plane is restored
following a process restart or route processor (RP) failover.
• Line card online insertion and removal (OIR)
Bridge Domain Support
IGMP snooping operates at the bridge domain level. When IGMP snooping is enabled on a bridge domain,
the snooping functionality applies to all ports under the bridge domain, including:
• Physical ports under the bridge domain.
• Ethernet flow points (EFPs)—An EFP can be a VLAN, VLAN range, list of VLANs, or an entire interface
port.
• Pseudowires (PWs) in VPLS bridge domains.
• Ethernet bundles—Ethernet bundles include IEEE 802.3ad link bundles and Cisco EtherChannel bundles.
From the perspective of the IGMP snooping application, an Ethernet bundle is just another EFP. The
forwarding application in the Cisco ASR 9000 Series Routers randomly nominates a single port from
the bundle to carry the multicast traffic.
Multicast Router and Host Ports
IGMP snooping classifies each port (for example, EFPs, PWs, physical ports, or EFP bundles) as one of the
following:
• Multicast router ports (mrouter ports)—These are ports to which a multicast-enabled router is connected.
Mrouter ports are usually dynamically discovered, but may also be statically configured. Multicast traffic
is always forwarded to all mrouter ports, except when an mrouter port is the ingress port.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
IGMP Snooping Overview
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