Introduction
This document explains how to configure Cisco Discovery Protocol (CDP) on Cisco routers and switches that run Cisco IOS®. Specifically, the document covers how to enable, verify, and disable CDP on Cisco devices and some know issues related to CDP.CDP is a Cisco proprietary Layer 2 protocol that is media- and protocol-independent, and runs on all Cisco-manufactured equipment that includes:
- routers
- bridges
- access servers
- switches
Prerequisites
Requirements
There are no specific requirements for this document.Components Used
This document is not restricted to specific software and hardware versions. This document applies to all Cisco routers and switches running Cisco IOS as well as router modules such as WS-X4232-L3, RSM, and MSFC.The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.Configure Cisco Discovery Protocol
Enable/Disable CDP on a Cisco IOS Device
CDP is enabled on Cisco routers by default. If you prefer not to use the CDP capability, disable it with the no cdp run command. In order to reenable CDP, use the cdp run command in global configuration mode.You can verify whether CDP is enabled or disabled on your Cisco device using the show cdp neighbors command.
Router#show cdp neighbors
% CDP is not enabled
!--- This message indicates that CDP is disabled on this device.
Router#Router#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
Router#
Router#show cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Sending CDPv2 advertisements is enabled
Router#Router#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
R2-AGS Ser 1 129 R 2500 Ser 0
R6-2500 Eth 0 144 R 4000 Eth 0
Router#- type of device that is discovered
- name of the device
- number and type of the local interface (port)
- number of seconds the CDP advertisement is valid for the port
- device type
- device product number
- port ID
router#show cdp neighbors detail
-------------------------
Device ID: lab-7206
Entry address(es):
IP address: 172.19.169.83
Platform: cisco 7206VXR, Capabilities: Router
Interface: Ethernet0, Port ID (outgoing port): FastEthernet0/0/0
Holdtime : 123 sec
Version :
Cisco Internetwork Operating System Software
IOS (tm) 5800 Software (C5800-P4-M), Version 12.1(2)
Copyright (c) 1986-2002 by Cisco Systems, Inc.
advertisement version: 2
Duplex: half
-------------------------
Device ID: lab-as5300-1
Entry address(es):
IP address: 172.19.169.87
Platform: cisco AS5300, Capabilities: Router
--More--
!--- Output is suppressed.
router#show cdp entry lab-7206 ------------------------- Device ID: lab-7206 Entry address(es): IP address: 172.19.169.83 Platform: cisco 7206VXR, Capabilities: Router Interface: Ethernet0, Port ID (outgoing port): FastEthernet0/0/0 Holdtime : 123 sec Version : Cisco Internetwork Operating System Software IOS (tm) 5800 Software (C5800-P4-M), Version 12.1(2) Copyright (c) 1986-2002 by Cisco Systems, Inc. advertisement version: 2 Duplex: half
Enable/Disable CDP on an Interface
When CDP is enabled globally using the cdp run command, it is enabled by default on all supported interfaces (except for Frame Relay multipoint subinterfaces) to send and receive CDP information. You can disable CDP on an interface that supports CDP with the no cdp enable command.Router#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
R2-AGS Ser 1 129 R 2500 Ser 0
R6-2500 Eth 0 144 R 4000 Eth 0
Router#The router does not remove the entry for the neighbor on CDP disabled interface unless the hold time expires. This output shows that the router discovered neighbor only on Ethernet 0 interface.Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#interface s1 Router(config-if)#no cdp enable Router(config-if)#^Z Router#4w5d: %SYS-5-CONFIG_I: Configured from console by console
Router#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
R6-2500 Eth 0 149 R 4000 Eth 0
Router#Router#show running-config int s1
Building configuration...
Current configuration : 94 bytes
!
interface Serial1 ip address 40.40.40.1 255.255.255.0
ip router isis
no cdp enable
!--- This command indicates that CDP is disabled on the Serial 1 interface.
end
Router#Sourece:: Cisco Website
No comments:
Post a Comment