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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 1 Product Overview
Layer 2 Software Features

Link State Tracking

Link-state tracking, also known as trunk failover, is a feature that binds the link state of multiple
interfaces. For example, link-state tracking provides redundancy in the network when used with server
NIC adapter teaming. When server network adapters are configured in a primary or secondary
relationship known as teaming, if the link is lost on the primary interface, connectivity is transparently
changed to the secondary interface.
For information on configuring Link State Tracking, see Chapter 22, “Configuring EtherChannel and
Link State Tracking.”
Location Service
The location service feature allows the switch to provide location and attachment tracking information
for its connected devices to a Cisco Mobility Services Engine (MSE). The tracked device can be a
wireless endpoint, a wired endpoint, or a wired switch or controller. The switch informs device link up
and link down events through encrypted Network Mobility Services Protocol (NMSP) location and
attachment notifications to the MSE.
For information on configuring LLDP, see Chapter 27, “Configuring LLDP, LLDP-MED, and Location
Service.”

Multiple Spanning Tree

IEEE 802.1s Multiple Spanning Tree (MST) allows for multiple spanning tree instances within a single
802.1Q or Inter-Switch Link (ISL) VLAN trunk. MST extends the IEEE 802.1w Rapid Spanning Tree
(RST) algorithm to multiple spanning trees. This extension provides both rapid convergence and load
balancing within a VLAN environment.
MST allows you to build multiple spanning trees over trunks. You can group and associate VLANs to
spanning tree instances. Each instance can have a topology independent of other spanning tree instances.
This new architecture provides multiple forwarding paths for data traffic and enables load balancing.
Network fault tolerance is improved because a failure in one instance (forwarding path) does not affect
other instances (forwarding paths).
For information on configuring MST, see Chapter 18, “Configuring STP and MST.”

Per-VLAN Rapid Spanning Tree

Per-VLAN Rapid Spanning Tree (PVRST+) is the implementation of 802.1w on a per-VLAN basis. It is
the same as PVST+ with respect to STP mode and runs RSTP protocol based on 802.1w.
For information on configuring PVRST+, see Chapter 18, “Configuring STP and MST.

Quality of Service

Note QoS functionality on Catalyst 4900M, Catalyst 4948E, Supervisor Enginess 6-E, and Supervisor
Engine 6L-E are equivalent.