© 2006, Shenzhen Polytechnic. All rights reserved. 1 Cisco 发现协议 Cisco Discovery Protocol 深圳职业技术学院计算机系网络专业

© 2006, Shenzhen Polytechnic. All rights reserved.. 2 教学目标（ Objectives ） 1. Cisco 发现协议特征（ Feature of Cisco Discovery Protocol ） 2.CDP 命令（ CDP Command ） 3. 开启和关闭 CDP （ Enable and disable CDP ） 4. 远程登录（ telnet ）

© 2006, Shenzhen Polytechnic. All rights reserved.. 3 Cisco 发现协议（ Cisco Discovery Protocol ） 1.Cisco 提供的专有的命令 CDP runs on all Cisco equipment 2. 获得直接连接的设备的信息摘要 The primary use of CDP is to discover all Cisco devices that are directly connected to a local device. 3. 运行在数据链路层 Cisco Discovery Protocol (CDP) is a Layer 2 protocol 4.Cdp 版本 1 在 10.3 版本后会自动启动 CDP Version 1 is enabled by default with Cisco IOS (Release 10.3 later). 5.cdp 更新周期 60 秒 CDP update timer is 60s 6.cdp 过期周期 180 秒 CDP hold timer is 180s

© 2006, Shenzhen Polytechnic. All rights reserved.. 4 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 用 CDP 发现邻居（ Discovering Neighbors with CDP ）

© 2006, Shenzhen Polytechnic. All rights reserved.. 5 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 R 2522 Ser 1 SwitchA Eth T S SwitchBRouterARouterBSwitchA S0 S1

© 2006, Shenzhen Polytechnic. All rights reserved.. 6 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 System Software IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fci) Copyright (c) by cisco Systems, Inc. Compiled Mon 08-Feb-99 18:18 by phanguye SwitchBRouterARouterBSwitchA S0 S1

© 2006, Shenzhen Polytechnic. All rights reserved.. 7 CDP 其它命令（ Additional CDP Commands ） RouterA#sh cdp traffic CDP counters : Packets output: 56, Input: 38 Hdr syntax: 0, Chksum error: 0, Encaps failed: 3 No memory: 0, Invalid packet: 0, Fragmented: 0 RouterA#sh cdp interface BRI0 is administratively down, line protocol is down Encapsulation HDLC Sending CDP packets every 60 seconds Holdtime is 180 seconds SwitchBRouterARouterBSwitchA S0 S1

© 2006, Shenzhen Polytechnic. All rights reserved 在全局配置模式下使用（ no ） cdp run 命令开启 或关闭所由接口的 CDP 功能。默认情况下， CDP 被 全局开启。 The cdp run command is used to enable CDP globally on the router. By default, CDP is globally enabled. 2. 在接口模式下使用（ no ） cdp enable 命令可以 开启或关闭某个特定接口的 CDP 功能。 CDP could be enabled on each of the devices interfaces by using the cdp enable command. 开启和关闭 CDP （ Enable and disable CDP ）

© 2006, Shenzhen Polytechnic. All rights reserved.. 9 配置周期（ Configuring Timer ） Router(config)#cdp timer 5 Router(config)# cdp holdtime 15

© 2006, Shenzhen Polytechnic. All rights reserved.. 10 用 telnet 连接到远程主机 （ Using Telnet to Connect to Remote Devices ） Remote device SwitchBRouterARouterBSwitchA S0 S1 RouterA#telnet Trying Open Catalyst 1900 Management Console Copyright (c) Cisco Systems, Inc All rights reserved. Enterprise Edition Software Ethernet Address: PCA Number: PCA Serial Number: FAA02359H8K Model Number: WS-C1924-EN System Serial Number: FAA0237X0FQ. RouterB>

© 2006, Shenzhen Polytechnic. All rights reserved.. 11 查看 telnet 连接（ Viewing Telnet Connections ） SwitchBRouterARouterBSwitchA S0 S1 RouterA#sh session Conn Host Address Byte Idle Conn Name * RouterA#sh user Line User Host(s) Idle Location * 0 con vty 0 idle

© 2006, Shenzhen Polytechnic. All rights reserved.. 12 挂起 telnet 会话（ Suspending a Telnet Session ） SwitchBRouterARouterBSwitchA S0 S1 RouterB# x RouterA#sh session Conn Host Address Byte Idle Conn Name RouterA#resume 1 RouterB#

© 2006, Shenzhen Polytechnic. All rights reserved.. 13 RouterA#disconnect Closing connection to [confirm] RouterA#clear line 11 [confirm] [OK] 关闭 telnet 会话（ Closing a Telnet Session ） Closing a session opened by a remote device Closing the current session opened by you SwitchBRouterARouterBSwitchA S0 S1

© 2006, Shenzhen Polytechnic. All rights reserved.. 14 思考题（ Questions ） 1 ． CDP 有哪些特征？ 2 ． CDP 的功能是什么？ 3 ．用 CDP 可以看到邻居的哪些信息？ 4 ．用什么命令可以在接口下控制 CDP 的启动？ 5 ．哪个符号是我们获得帮助时最常用的？ 6 ． telnet 默认支持几个用户同时登录？