12. Manage network environment

One 、 Find neighbors in the network

1、Cisco Discovery Protocol （CDP）

CDP Is a proprietary tool for use , He can tell you the current direct connection Cisco Routers, switches and some others Cisco Comprehensive information of the equipment . No matter what protocol is running on these devices ,CD You can find them .

2、 adopt CDP Find a neighbor

CDP It can only run on Cisco On the device ,IOS Version in 10.3 Or above

Summary information includes

Device identifiers       

Address list            

Port identifiers             

Capabilities list

Platform

3、 experiment

3.1 Topology

3.2、cdp Overview information

Router#show cdp

Global CDP information:

    Sending CDP packets every 60 seconds                     every 60 Seconds to send cdp Information

    Sending a holdtime value of 180 seconds                 exceed 180s Didn't receive the other party cdp Information , Delete the corresponding information

    Sending CDPv2 advertisements is enabled                 Version information

3.3 View link information

Router#show cdp neighbors     View which devices are currently linked

Router#show cdp neighbors 

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID    Local Intrfce   Holdtme    Capability   Platform    Port ID

Router       Ser 0/3/0        141            R       C2800       Ser 0/3/0

Router       Ser 0/3/1        144            R       C2800       Ser 0/3/1

Holdtme： Generally in 120 above , Be equal to 0 This device information will be deleted

show cdp interface   All ports CDP Information about

Vlan1 is administratively down, line protocol is down

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

FastEthernet0/0 is administratively down, line protocol is down

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

FastEthernet0/1 is administratively down, line protocol is down

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

Serial0/3/0 is up, line protocol is up

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

Serial0/3/1 is down, line protocol is down

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

show cdp entry *         View details of all neighbors , and Router#show cdp  neighbors detail The display information is exactly the same

Router#show cdp entry * ?

  protocol  Protocol information             neighbor IP Address

  version   Version information             neighbor IOS Version of

4、 On off cdp

Router(config)#cdp run                 Global on cdp

Router(config)#no cdp run               Global close cdp

Router(config)#interface fastEthernet 0/1

Router(config-if)#cdp enable                         Open a single interface cdp

Router(config-if)#no cdp enable                       Close a single interface cdp

Two 、 Use Telnet Link remote devices

1、 summary

Remote link management software , Working in the application layer , port 23. If not set Telnet password , Cannot be used by default Telnet link . without enable Mode password , Unable to switch to privileged mode

2、

Router#configure terminal 

Router(config)#line vty 0 15

Router(config-line)#password 123456

Router(config-line)#login 

Router(config)#enable password 123456

Router(config-line)#no login                 Anonymous logins

Router#Ctrl+Shift+6                 meanwhile Telnet Multiple devices

Router#show sessions                Check Telnet link

Router#show users                   Check Telnet user

Router#clear line 66               Kick people 66 For the thread number ,show users View thread number

Router#disconnect                  Telnet After use Ctrl+Shift+6 After cutting out , To break off Telnet link （ Use... When linking with exit sign out ）

Router(config)#ip host R1 192.168.2.1             Set up the host table

Router(config)#no ip host R1                       Delete host table

Router(config)#no ip domain-lookup                 prohibit DNS Domain name resolution

Router#R1                                         Telnet R1 Direct input IP Default Telnet