- Title
- 3800x3600xscgTOC
- Preface
- Overview
- Using the Command-Line Interface
- Assigning the Switch IP Address and Default Gateway
- Configuring Cisco IOS Configuration Engine
- Administering the Switch
- Configuring Synchronous Ethernet
- Configuring the Switch External Alarms
- Configuring SDM Templates
- Configuring Switch-Based Authentication
- Configuring Interfaces
- Configuring VLANs
- Configuring Ethernet Virtual Connections (EVCs)
- Configuring Command Macros
- Configuring STP
- Configuring MSTP
- Configuring Optional Spanning-Tree Features
- Configuring Resilient Ethernet Protocol
- Configuring DHCP Features
- Configuring Dynamic ARP Inspection
- Configuring IGMP Snooping
- Configuring PIM Snooping
- Configuring IEEE 802.1x Port-Based Authentication
- Configuring IEEE 802.1ad
- Configuring Traffic Control
- Configuring CDP
- Configuring LLDP and LLDP-MED
- Configuring UDLD
- Configuring System Message Logging
- Configuring RMON
- Using the SD Flash Memory Module
- Configuring SNMP
- Configuring Embedded Event Manager
- Configuring Network Security with ACLs
- Configuring IPv6 ACLs
- Configuring Quality of Service (QoS)
- Hierarchical Color-Aware Policing
- Configuring Multi-level Priority Queues
- Configuring Policy-Based Routing (PBR)
- Configuring Control Plane Policing (CoPP)
- Configuring EtherChannels
- Configuring IP Unicast Routing
- Configuring IPv6 Unicast Routing
- Configuring IPv6 VPN over MPLS
- Configuring Virtual Router Redundancy Protocol
- Configuring HSRP
- Configuring Cisco IOS IP SLAs Operations
- Configuring Enhanced Object Tracking
- Configuring Ethernet OAM, CFM, and E-LMI
- Configuring Y.1731 Performance Monitoring
- Configuring Ethernet Data Plane Loopback
- L2VPN Protocol-Based CLIs
- Configuring IP Multicast Routing
- Configuring Multicast VPN
- Configuring MPLS, MPLS VPN, MPLS OAM, and EoMPLS
- Multiprotocol Label Switching Load Balancing
- MPLS Traffic Engineering Bundled Interface Support
- Configuring OSPF TTL Security Check
- Configuring Switched Port Analyzer (SPAN)
- Configuring Ethernet Ring Protection
- Auto-IP
- Troubleshooting
- Configuring Online Diagnostics
- Supported MIBs
- Working with the Cisco IOS File System, Configuration Files, and Software Images
- Configuring MPLS Transport Profile
- Unsupported Commands
- Index
Cisco ME 3800x and ME 3600x Switches Software Configuration Guide, Cisco IOS Release 15.4(2)S
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- Updated:
- April 7, 2021
Chapter: Configuring CDP
Configuring CDP
This chapter describes how to configure Cisco Discovery Protocol (CDP) on the Cisco ME 3800X and ME 3600X switch.
Note
For complete syntax and usage information for the commands used in this chapter, see the command reference for this release and the Cisco IOS Configuration Fundamentals Command Reference at
http://www.cisco.com/en/US/docs/ios-xml/ios/fundamentals/command/Cisco_IOS_Configuration_Fundamentals_Command_Reference.html
Understanding CDP
CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices. With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices running lower-layer, transparent protocols. This feature enables applications to send SNMP queries to neighboring devices.
CDP runs on all media that support Subnetwork Access Protocol (SNAP). Because CDP runs over the data-link layer only, two systems that support different network-layer protocols can learn about each other.
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.
Configuring CDP
- Default CDP Configuration
- Configuring the CDP Characteristics
- Disabling and Enabling CDP
- Disabling and Enabling CDP on an Interface
- CDP and Ethernet Flow Points (EFPs)
Default CDP Configuration
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Configuring the CDP Characteristics
You can configure the frequency of CDP updates, the amount of time to hold the information before discarding it, and whether or not to send Version-2 advertisements.
Beginning in privileged EXEC mode, follow these steps to configure the CDP timer, holdtime, and advertisement type.
Note Steps 2 through 4 are all optional and can be performed in any order.
Use the no form of the CDP commands to return to the default settings.
This example shows how to configure CDP characteristics.
For additional CDP show commands, see the “Monitoring and Maintaining CDP” section.
Disabling and Enabling CDP
Note Cisco devices (such as Cisco IP Phones) regularly exchange CDP messages with connected devices. Disabling CDP can interrupt device connectivity.
Beginning in privileged EXEC mode, follow these steps to globally disable the CDP device discovery capability:
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Beginning in privileged EXEC mode, follow these steps to globally enable CDP when it has been disabled:
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This example shows how to globally enable CDP if it has been disabled.
Disabling and Enabling CDP on an Interface
CDP is enabled by default to send and to receive CDP information.
Beginning in privileged EXEC mode, follow these steps to disable CDP on a port:
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Specify the interface on which you are disabling CDP, and enter interface configuration mode. |
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Beginning in privileged EXEC mode, follow these steps to enable CDP on a port when it has been disabled:
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Specify the interface on which you are enabling CDP, and enter interface configuration mode. |
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This example shows how to enable CDP on a port when it has been disabled.
CDP and Ethernet Flow Points (EFPs)
For CDP to peer with a neighbor on a port that has an Ethernet Virtual Connection (EVC) EFP service instance configured, you need to enter the l2 protocol peer cdp service-instance configuration command on the service instance. See the “Configuring Ethernet Virtual Connections (EVCs)” chapter for more information on EFPs.
This example shows how to configure Layer 2 protocol peer on a service instance:
Switch (config)# interface gigabitethernet0/1
Switch (config-if)# switchport mode trunk
Switch (config-if)# switchport trunk allowed vlan none
Switch (config-if)# service instance 1 Ethernet
Switch (config-if-srv)# encapsulation untagged
Switch (config-if-srv)# l2protocol peer cdp
Switch (config-if-srv)# bridge-domain 10
Switch (config-if-srv)# end
Monitoring and Maintaining CDP
To monitor and maintain CDP on your device, use one or more of these commands in privileged EXEC mode.
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