Availability And Redundancy Features - Cisco Catalyst 2928 Software Configuration Manual

Chapter 1 Overview

Availability and Redundancy Features

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VLAN Features
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OL-23389-01
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 64 spanning-tree instances supported
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Per-VLAN spanning-tree plus (PVST+) for load balancing across VLANs
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– Rapid PVST+ for load balancing across VLANs and providing rapid convergence of
spanning-tree instances
UplinkFast and BackboneFast for fast convergence after a spanning-tree topology change and
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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 Spanning Tree
Protocol (RSTP) for rapid convergence of the spanning tree by immediately changing 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 change from
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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
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failure that leads to a unidirectional link
Support for up to 64 VLANs for assigning users to VLANs associated with appropriate network
resources, traffic patterns, and bandwidth
Support for VLAN IDs in the 1 to 4094 range as allowed by the IEEE 802.1Q standard
VLAN Query Protocol (VQP) for dynamic VLAN membership
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 (IEEE 802.1Q) 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
Catalyst 2928 Switch Software Configuration Guide
Features
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