Flex Links And Mac Address-Table Move Update - Cisco Catalyst 4500 Series Configuration Manual

Layer 2 Software Features

Flex Links and MAC Address-Table Move Update

Flex Links are a pair of Layer 2 interfaces (switch ports or port channels) where one interface is
configured to act as a backup to the other. The feature provides an alternative solution to the Spanning
Tree Protocol (STP). Flex Links are typically configured in service provider or enterprise networks
where customers do not want to run STP on the switch.
MAC Address-Table Move Update allows a switch to provide rapid bidirectional convergence when a
primary (forwarding) link goes down and the standby link begins forwarding traffic.
For information about Flex Links and MAC Address-Table Move Update, see
Flex Links and MAC Address-Table Move Update."
Flexible NetFlow
Flexible NetFlow is only supported on Supervisor Engine 7-E, Supervisor Engine 7L-E, and Catalyst
Note
4500X.
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
Internet Group Management Protocol (IGMP) Snooping
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
1-4
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.
For information on configuring IGMP snooping, see
Chapter 1
Chapter 21, "Configuring
Chapter 62, "Configuring Flexible NetFlow."
Product Overview
OL-25340-01