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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 1 Product Overview
Layer 2 Software Features
For information about Flex Links and MAC Address-Table Move Update, see Chapter 24, “Configuring
Flex Links and MAC Address-Table Move Update.”
Flexible NetFlow (Supervisor Engine 7-E, 7L-E, and 8-E only)
Flow is defined as unique set of key fields attributes, which might include fields of packet, packet routing
attributes, and input and output interface information. A NetFlow feature defines a flow as a sequence
of packets that have the same values for the feature key fields. Flexible NetFlow (FNF) allows a flow
record that specifies various flow attributes to be collected and optionally exported. NetFlow collection
supports IP, IPv6 and Layer 2 traffic.
For information on configuring Flexible NetFlow, see Chapter 74, “Configuring Flexible NetFlow.”
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.
With SSO support, Stateful IGMP Snooping propagates the IGMP data learned by the active
supervisor engine to the redundant supervisor engine so that when a switchover occurs, the newly
active supervisor engine is aware of the multicast group membership, which alleviates a disruption
to multicast traffic during a switchover.
Beginning with Release IOS XE 3.5.0E and IOS 15.2(1)E, the Catalyst 4500 series switch supports
an application of local IGMP snooping, Multicast VLAN Registration (MVR). MVR is designed for
applications using wide-scale deployment of multicast traffic across an Ethernet ring-based service
provider network (for example, the broadcast of multiple television channels over a service-provider
network). MVR allows a subscriber on a port to subscribe and unsubscribe to a multicast stream on
the network-wide multicast VLAN. It allows the single multicast VLAN to be shared in the network
while subscribers remain in separate VLANs.
For information on configuring IGMP snooping and MVR, see Chapter 28, “Configuring IGMP
Snooping and Filtering, and MVR.”
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