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Catalyst 2940 Switch Software Configuration Guide
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Chapter 1 Overview
Features
• Default configuration storage in Flash memory to ensure that the switch can be connected to a
network and can forward traffic with minimal user intervention
• In-band management access through a CMS web-based session
• In-band command-line interface (CLI) management using Telnet connections
• In-band management access through SNMP versions 1, 2c, and 3 get-and-set requests
• Out-of-band management access through the switch console port to a directly-attached terminal or
to a remote terminal through a serial connection and a modem
Note For additional descriptions of the management interfaces, see the “Management Options”
section on page 1-5.
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 plus (PVST+) for balancing load across LANs
–
UplinkFast and BackboneFast for fast convergence after a spanning-tree topology change and
for achieving load balancing between redundant uplinks, including Gigabit uplinks
• VLAN 1 minimization to reduce 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. The switch CPU continues to send and receive control protocol frames
• Optional spanning-tree features available in the PVST+ 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 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 four spanning-tree instances.
VLAN Support
• The Catalyst 2940 switch supports 4 port-based VLANs for assigning users to VLANs associated
with appropriate network resources, traffic patterns, and bandwidth
• 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
