Cisco Systems 2960-S, 2960 Availability and Redundancy Features

1-8
Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 1 Overview
Features
• USB mini-Type B console port in addition to the standard RJ-45 console port. Console input is
active on only one port at a time. (Catalyst 2960-S only)
• USB Type A port for external Cisco USB flash memory devices (thumb drives or USB keys). You
can use standard Cisco CLI commands to read, write, erase, copy, or boot from the flash memory.
(Catalyst 2960-S only)
Availability and Redundancy Features
• Automatic stack master re-election for replacing stack masters that become unavailable (failover
support)
The newly elected stack master begins accepting Layer 2 traffic in less than 1 second and Layer 3
traffic between 3 to 5 seconds.
• Cross-stack EtherChannel for providing redundant links across the switch stack
• UniDirectional Link Detection (UDLD) and aggressive UDLD for detecting and disabling
unidirectional links on fiber-optic interfaces caused by incorrect fiber-optic wiring or port faults
• IEEE 802.1D Spanning Tree Protocol (STP) for redundant backbone connections and loop-free
networks. STP has these features:
– Up to 128 spanning-tree instances supported
Note Up to 64 spanning-tree instances are supported when the s witch is running the LAN Lite
image.
– Per-VLAN spanning-tree plus (PVST+) for load balancing across VLANs
– Rapid PVST+ for load balancing across VLANs and providing rapid convergence of
spanning-tree instances
– UplinkFast, cross-stack UplinkFast, and BackboneFast for fast convergence after a
spanning-tree topology change and for achieving load balancing between redundant uplinks,
including Gigabit uplinks and cross-stack Gigabit uplinks
– UplinkFast and BackboneFast for fast convergence after a spanning-tree topology change and
for achieving load balancing between redundant uplinks, including Gigabit uplinks
• IEEE 802.1s Multiple Spanning Tree Protocol (MSTP) for grouping VLANs into a spanning-tree
instance and for providing multiple forwarding paths for data traffic and load balancing and rapid
per-VLAN Spanning-Tree plus (rapid-PVST+) based on the IEEE 802.1w Rapid Spa nning Tree
Protocol (RSTP) for rapid convergence of the spanning tree by immediately chang ing root and
designated ports to the forwarding state
• Optional spanning-tree features available in PVST+, rapid-PVST+, and MST P mode:
– Port Fast for eliminating the forwarding delay by enabling a port to immediately change from
the blocking state to the forwarding state
– BPDU guard for shutting down Port Fast-enabled ports that receive bridge protocol data units
(BPDUs)
– BPDU filtering for preventing a Port Fast-enabled port from sending or receiving BPDUs
– Root guard for preventing switches outside the network core from becoming the spanning-tree
root