![Page 1: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/1.jpg)
Module 4 – Learning about other Devices
Testing network connections
![Page 2: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/2.jpg)
Tools
• CDP - • Ping – Packet Internet Groper• Traceroute (Trace, Tracert) – • Telnet
![Page 3: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/3.jpg)
CDP
• Used to obtain information about neighboring Cisco devices
• Uses a Layer 2 *proprietary* protocol
• CDP Version 2 (CDPv2) latest version – needs IOS 12.0(3)T or later
• CDP Version 1 used from IOS 10.3 to 12.0(3)T
![Page 4: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/4.jpg)
CDP
• Protocol independent– Layer 2 protocol
• therefore Layer-3 independent – media independent
![Page 5: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/5.jpg)
Show cdp neighbors
• CDP discovers all Cisco devices that are directly connected to a local device
• Show CDP Neighbors Command displays a summary of info about the neighbors
![Page 6: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/6.jpg)
Show cdp neighbors
• CDP v1 and CDPv2 displays
– Device ID – Local Interface – Holdtime – Capability – Platform – Port ID
• CDPv2 (only) also displays
– VTP management domain name
– Native VLAN – Full or half-duplex
![Page 7: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/7.jpg)
• Show details for a specific CDP neighbors entry
Show cdp entry
![Page 8: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/8.jpg)
Show cdp interface
• Show CDP setup parameters for the specified interface
![Page 9: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/9.jpg)
The show cdp traffic Command
![Page 10: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/10.jpg)
CDP commands
![Page 11: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/11.jpg)
Starting and Stopping CDP
• Global cdp enable/disable
– Router(config)# cdp run
– Router(config)# no cdp run
• Interface level cdp enable/disable
– interface FastEthernet 0/0– Router(config-interface)# cdp run– Router(config-interface)# no cdp run
![Page 12: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/12.jpg)
Telnet
• Application-level tool• Mainly used to establish remote connections to network devices
![Page 13: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/13.jpg)
Telnet Operation
• Available in User or Privileged EXEC mode• Default inactivity time – 10 minutes
• Can remotely connect to the Paris router from the Denver router – if both routers have been previously configured
Denver> telnet Paris (or connect Paris)or
Denver> telnet 131.108.100.152
Paris> ….Paris> exit
Denver>
![Page 14: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/14.jpg)
Telnet
![Page 15: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/15.jpg)
Advanced Telnet Operation
Multiple Telnet sessions can be used and suspended with the Ctrl+Shift+6 then x sequence.
![Page 16: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/16.jpg)
Ping
• Packet Internet Groper (PING)• Operates at Layer 3• Uses ICMP echo request and echo response• Tests end-to-end connectivity
![Page 17: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/17.jpg)
PING
• Uses ICMP messages
• Sends an ICMP echo request and waits for an ICPM echo reply
• Cisco codes:
! receipt of an echo reply message
. time out
U ICMP unreachable message received (no route)
C Source Quench ICMP unreachable message received
![Page 18: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/18.jpg)
Traceroute (trace)
![Page 19: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/19.jpg)
Traceroute
• Operates at Layer 3
• Sets TTL in IP packet header to expire at subsequent routers from the closest router to the furtherest router
• Tests each step along the route to destination
• Cisco codes:
– nn msec RTT for number of probes– * probe timed out– A administratively prohibited– Q source quench– H ICMP unreachable message received
![Page 20: Module 4 – Learning about other Devices Testing network connections](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56649e055503460f94af1d6e/html5/thumbnails/20.jpg)
Troubleshooting
• Ping• Traceroute• Telnet• show interfaces• show ip route• debug