1. Module 4 – Learning about other Devices Testing network connections

2. Tools CDP - Ping – Packet Internet Groper Traceroute (Trace, Tracert) – Telnet

3. 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

4. CDP Protocol independent –Layer 2 protocol therefore Layer-3 independent –media independent

5. 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

6. 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

7. Show details for a specific CDP neighbors entry Show cdp entry

8. Show cdp interface Show CDP setup parameters for the specified interface

9. The show cdp traffic Command

10. CDP commands

11. 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

12. Telnet Application-level tool Mainly used to establish remote connections to network devices

13. 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>

14. Telnet

15. Advanced Telnet Operation Multiple Telnet sessions can be used and suspended with the Ctrl+Shift+6 then x sequence.

16. Ping Packet Internet Groper (PING) Operates at Layer 3 Uses ICMP echo request and echo response Tests end-to-end connectivity

17. 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

18. Traceroute (trace)

19. 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

20. Troubleshooting Ping Traceroute Telnet show interfaces show ip route debug