Configuring Cdp; Understanding How Cdp Works - Cisco 6500 Series Software Configuration Manual

Configuring CDP

This chapter contains information about how to configure Cisco Discovery Protocol (CDP) on the
Catalyst 6500 series switches, which supplements the information in these publications:
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This chapter consists of these sections:
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Understanding How CDP Works

CDP is a protocol that runs over Layer 2 (the data link layer) on all Cisco routers, bridges, access servers,
and switches. CDP allows network management applications to discover Cisco devices that are
neighbors of already known devices, in particular, neighbors running lower-layer, transparent protocols.
With CDP, network management applications can learn the device type and the SNMP agent address of
neighboring devices. This feature enables applications to send SNMP queries to neighboring devices.
CDP runs on all LAN and WAN media that support Subnetwork Access Protocol (SNAP).
Each CDP-configured device sends periodic messages to a multicast address. Each device advertises at
least one address at which it can receive SNMP messages. The advertisements also contain the
time-to-live, or holdtime information, which indicates the length of time a receiving device should hold
CDP information before discarding it.
Configuring CDP
These sections describe how to configure CDP:
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The Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.1, "Cisco IOS System
Management," "Configuring Cisco Discovery Protocol (CDP)" at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/fun_c/fcprt3/fcd301c.htm
The Cisco IOS Configuration Fundamentals Command Reference, Release 12.1, "Cisco IOS System
Management Commands," "CDP Commands" publication at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/fun_r/frprt3/frd3001b.htm
Understanding How CDP Works, page 30-1
Configuring CDP, page 30-1
Enabling CDP Globally, page 30-2
Displaying the CDP Global Configuration, page 30-2
Enabling CDP on a Port, page 30-2
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
C H A P T E R
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