Specifications

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Catalyst 2970 Switch Software Configuration Guide
78-15462-03
Chapter 1 Overview
Features
– Rapid PVST+ for balancing load across VLANs and providing rapid convergence of
spanning-tree instances
– 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
IEEE 802.1W Rapid Spanning Tree Protocol (RSTP) for rapid convergence of the spanning tree by
immediately transitioning root and designated ports to the forwarding state
• Optional spanning-tree features available in PVST+, rapid-PVST+, and MSTP mode:
– Port Fast for eliminating the forwarding delay by enabling a port to immediately transition 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
– Loop guard for preventing alternate or root ports from becoming designated ports because of a
failure that leads to a unidirectional link
• RPS support through the Cisco RPS 300 and Cisco RPS 675 for enhancing power reliability
VLAN Features
• Support for up to 1005 VLANs for assigning users to VLANs associated with appropriate network
resources, traffic patterns, and bandwidth
• Support for VLAN IDs in the full 1 to 4094 range allowed by the IEEE 802.1Q standard
• VLAN Query Protocol (VQP) for dynamic VLAN membership
• Inter-Switch Link (ISL) and IEEE 802.1Q trunking encapsulation on all ports for network moves,
adds, and changes; management and control of broadcast and multicast traffic; and network security
by establishing VLAN groups for high-security users and network resources
• Dynamic Trunking Protocol (DTP) for negotiating trunking on a link between two devices and for
negotiating the type of trunking encapsulation (802.1Q or ISL) to be used
• VLAN Trunking Protocol (VTP) and VTP pruning for reducing network traffic by restricting
flooded traffic to links destined for stations receiving the traffic
• Voice VLAN for creating subnets for voice traffic from Cisco IP Phones
• VLAN1 minimization for reducing the risk of spanning-tree loops or storms by allowing VLAN 1
to be disabled on any individual VLAN trunk link. With this feature enabled, no user traffic is sent
or received on the trunk. The switch CPU continues to send and receive control protocol frames.
Security Features
Note The Kerberos feature listed in this section is available only on the cryptographic (that is, supports
encryption) version of the switch software image.
• Password-protected access (read-only and read-write access) to management interfaces (CMS and
CLI) for protection against unauthorized configuration changes