Configuring Cdp; Understanding How Cdp Works - Cisco 7604 Configuration Manual

Configuring CDP

This chapter contains information about how to configure Cisco Discovery Protocol (CDP) on the
Cisco 7600 series routers, which supplements the information in these publications:
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This chapter consists of these sections:
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For additional information (including configuration examples and troubleshooting information), see the
Tip
documents listed on this page:
http://www.cisco.com/en/US/products/hw/routers/ps368/tsd_products_support_series_home.html

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.
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The Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.2, "System
Management," "Configuring Cisco Discovery Protocol (CDP)" at this URL:
http://www.cisco.com/en/US/docs/ios/12_2/configfun/configuration/guide/fcf015.html
The Cisco IOS Configuration Fundamentals Command Reference, Release 12.2, "System
Management Commands," "CDP Commands" publication at this URL:
http://www.cisco.com/en/US/docs/ios/12_2/configfun/command/reference/frf015.html
Understanding How CDP Works, page 48-1
Configuring CDP, page 48-2
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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