文档介绍：教学目标（ Objectives ）
1. Cisco发现协议特征（Feature of Cisco Discovery Protocol ）
（CDP Command ）
（Enable and disable CDP）
4. 远程登录（telnet ）
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Cisco发现协议（ Cisco Discovery Protocol ）
CDP runs on all Cisco equipment
The primary use of CDP is to discover all Cisco devices that are directly connected to a local device.
Cisco Discovery Protocol (CDP) is a Layer 2 protocol
CDP Version 1 is enabled by default with Cisco IOS (Release later).
CDP update timer is 60s
CDP hold timer is 180s
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信息摘要包括（Summary information includes）:
设备ID（Device ID）
本地接口（Local Interface ）
保持时间（Holdtime ）
功能（Capability ）
平台（Platform ）
端口ID（Port ID ）
VTP域名（VTP Management Domain Name (CDPv2 only) ）
本征VLAN（Native VLAN (CDPv2 only) ）
全双工/半双工（Full/Half-Duplex (CDPv2 only) ）
CDP
show cdp
CDP
CDP
用CDP发现邻居（Discovering Neighbors with CDP）
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Using the show cdp neighbor Command
RouterA#sh 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
RouterB Ser 0 148 R 2522 Ser 1
SwitchA Eth 0 167 T S 1900 2
SwitchB
RouterA
RouterB
SwitchA
S0
S1
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Using the show cdp entry Command
RouterA#sh cdp entry *
-------------------------
Device ID: RouterB
Entry address(es):
IP address:
Platform: cisco 2522, Capabilities: Router
Interface: Serial0, Port ID (outgoing port): Serial1
Holdtime : 168 sec
Version :
Cisco Internetwork Operating Syst