Each CDP-configured device sends periodic messages to a multicast address, advertising at least one address
at which it can receive SNMP messages. The advertisements also contain time-to-live, or holdtime information,
which is the length of time a receiving device holds CDP information before discarding it. Each device also
listens to the messages sent by other devices to learn about neighboring devices.
On the switch, CDP enables Network Assistant to display a graphical view of the network. The switch uses
CDP to find cluster candidates and maintain information about cluster members and other devices up to three
cluster-enabled devices away from the command switch by default.
Related Topics
Configuring CDP Characteristics, on page 432
Monitoring and Maintaining CDP, on page 441
CDP and Stacks
A switch stack appears as a single switch in the network. Therefore, CDP discovers the switch stack, not the
individual stack members. The switch stack sends CDP messages to neighboring network devices when there
are changes to the switch stack membership, such as stack members being added or removed.
Default CDP Configuration
This table shows the default CDP configuration.
Default SettingFeature
EnabledCDP global state
EnabledCDP interface state
60 secondsCDP timer (packet update frequency)
180 secondsCDP holdtime (before discarding)
EnabledCDP Version-2 advertisements
Related Topics
Enabling CDP, on page 436
Disabling CDP, on page 434
Enabling CDP on an Interface, on page 439
Disabling CDP on an Interface, on page 437
How to Configure CDP
Configuring CDP Characteristics
You can configure these CDP characteristics:
•
Frequency of CDP updates
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
432
How to Configure CDP
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