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Catalyst 2940 Switch Software Configuration Guide
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Chapter1 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 ge t-a nd -set re qu ests
•Out-of-band management access through the switch console port to a directly-attached terminal or
to a remote terminal through a serial connection an d a mod em
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 port s fo r de tec ting an d disab lin g
unidirectional links on fiber-optic interfaces caused by incorrect fiber-optic wiring or po rt fault s.
•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 loop s o r s to rms by allowing VL AN 1 to
be disabled on any individual VLAN trunk link. With this feature enabled, no user tra ffic 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 beca use 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 c hanges; 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