Cisco Catalyst 2950 Software Configuration Manual page 32

Features
Table 1-1 Features (continued)
Redundancy
HSRP for command switch redundancy
•
UniDirectional link detection (UDLD) on all Ethernet ports 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:
Per-VLAN Spanning Tree (PVST) for balancing load across VLANs
–
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
• IEEE 802.1S Multiple STP (MSTP) for grouping VLANs into a spanning-tree instance, and providing for multiple
forwarding paths for data traffic and load balancing
• IEEE 802.1W Rapid STP (RSTP) for rapid convergence of the spanning tree by immediately transitioning root and
designated ports to the forwarding state
• Optional spanning-tree features available:
– 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 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
Note The switch supports up to 64 spanning-tree instances.
VLAN Support
Catalyst 2950 switches support 250 port-based VLANs for assigning users to VLANs associated with appropriate
•
network resources, traffic patterns, and bandwidth
The Catalyst 2950-12 and Catalyst 2950-24 switches support only 64 port-based VLANs.
Note
The switch supports up to 4094 VLAN IDs to allow service provider networks to support the number of VLANs allowed by
•
the IEEE 802.1Q standard
IEEE 802.1Q trunking protocol 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
VLAN Membership Policy Server (VMPS) for dynamic VLAN membership
•
VLAN Trunking Protocol (VTP) pruning for reducing network traffic by restricting flooded traffic to links destined for
•
stations receiving the traffic
Dynamic Trunking Protocol (DTP) for negotiating trunking on a link between two devices and for negotiating the type
•
of trunking encapsulation (802.1Q) to be used
Voice VLAN for creating subnets for voice traffic from Cisco IP Phones
•
Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 1 Overview
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