Cisco Catalyst 4500 series Administration Manual page 88

Layer 3 Software Features
ANCP Client —ANCP Multicast enables you to control multicast traffic on a Catalyst 4500 switch
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using either ANCP (rather than IGMP) or direct static configuration on the CLI.
• Cisco Group Management Protocol (CGMP) server—CGMP server manages multicast traffic.
Multicast traffic is forwarded only to ports with attached hosts that request the multicast traffic.
• Internet Group Management Protocol (IGMP) snooping—IGMP snooping manages multicast
traffic. The switch software examines IP multicast packets and forwards packets based on their
content. Multicast traffic is forwarded only to ports with attached hosts that request multicast traffic.
Support for IGMPv3 provides constrained flooding of multicast traffic in the presence of IGMPv3
hosts or routers. IGMPv3 snooping listens to IGMPv3 query and membership report messages to
maintain host-to-multicast group associations. It enables a switch to propagate multicast data only
to ports that need it. IGMPv3 snooping is fully interoperable with IGMPv1 and IGMPv2.
Explicit Host Tracking (EHT) is an extension to IGMPv3 snooping. EHT enables immediate leave
operations on a per-port basis. EHT can be used to track per host membership information or to
gather statistics about all IGMPv3 group members.
The IGMP Snooping Querier is a Layer 2 feature required to support IGMP snooping in a VLAN
where PIM and IGMP are not configured because the multicast traffic does not require routing.
For information on configuring IGMP snooping, see
Filtering, and MVR."
IPv6 Multicast Listen Discovery (MLD) and Multicast Listen Discovery snooping—MLD is a
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protocol used by IPv6 multicast devices to discover the presence of multicast listeners (nodes that
want to receive IPv6 multicast packets) on its directly attached links and to discover which multicast
packets are of interest to neighboring nodes. MLD snooping is supported in two different versions:
MLD v1 and MLD v2. Network switches use MLD snooping to limit the flood of multicast traffic,
causing IPv6 multicast data to be selectively forwarded to a list of ports that want to receive the data,
instead of being flooded to all ports in a VLAN. This lessens the load on devices in the network,
minimizing unnecessary bandwidth on links, enabling efficient distribution of IPv6 multicast data.
For information on configuring multicast services, see
Listener Discovery Snooping."
Protocol Independent Multicast (PIM)—PIM is protocol-independent because it can leverage
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whichever unicast routing protocol is used to populate the unicast routing table, including EIGRP,
OSPF, BGP, or static route. PIM also uses a unicast routing table to perform the Reverse Path
Forwarding (RPF) check function instead of building a completely independent multicast routing
table.
For information on PIM-SSM mapping, see the URL:
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/15.1SY/config_guide/sup720/ude
_udlr.html
IP Multicast Load Splitting (Equal Cost Multipath (ECMP) Using S, G and Next Hop)—
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IP Multicast Load Splitting introduces more flexible support for ECMP multicast load splitting by
adding support for load splitting based on source and group address and on source, group, and
next-hop address. This feature allows multicast traffic from devices that send many streams to
groups or that broadcast many channels, such as IPTV servers or MPEG video servers, to be more
effectively load shared across equal-cost paths.
For information on configuring multicast services, see
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
1-20
Chapter 1
Chapter 27, "Configuring IGMP Snooping and
Chapter 28, "Configuring IPv6 Multicast
Chapter 37, "Configuring IP Multicast."
Product Overview
OL-30933-01