In preparation of our CCNA exam, we want to make sure we cover the various concepts that we could see on our Cisco CCNA exam. So to assist you, below we will discuss Network Devices.

Managing Your Network Environment
Discovering Neighbors with CDP
CDP is a proprietary tool that enables access to protocol and address information on directly connected devices. CDP runs over the data link layer, allowing different network-layer protocols to learn about each other. CDP runs over all LANs, Frame Relay, ATM, and other WANs employing SNAP encapsulation. CDP starts up by default on bootup and sends updates every 60 seconds.
  • show cdp—Allows you to view CDP output.
  • cdp enable—Enables CDP on an interface. no cdp enable disables.
  • cdp run—Allows other CDP devices to get information about your device.
  • no cdp run—Prevents other CDP devices from getting information about your device.
  • show cdp neighbors—Displays the CDP updates received on the local interfaces.
  • show cdp neighbors detail—Displays updates received on the local interfaces. This command displays the same information as the show cdp entry * command.
  • show cdp entry—Displays information about neighboring devices.
  • show cdp traffic—Displays information about interface traffic.
  • show cdp interface—Displays information about interface status and configuration.
    Discovering Neighbors with CDP Summary
  • CDP gathers information on directly connected devices.
  • CDP passes packets of information between neighboring devices.
  • The show cdp neighbors command yields the following information for adjacent devices: attached interfaces, hardware platform, and remote port ID.
  • The show cdp entry * command yields some Layer 3 protocol information (such as IP addresses).
    Getting Information About Remote Devices
    Telnet is an underlying TCP/IP protocol for accessing remote computers. It allows connections and remote console sessions from one device to one or more other remote devices.
    Telnet Procedure
    To establish a Telnet session, use the telnet or connect commands. A router’s IP address and host name can be used as delimiters.
    RouterB#connect RouterA
    RouterA#show sessions
    Note: show sessions displays a list of connected hosts.
    Suspending and Resuming Sessions
    Press Ctrl-Shift-6 and then press x to suspend the current session.
    Press Enter or enter resume to resume the last active session.
    resume session # reconnects you to a specific session.
    The show session command finds the session number.
    You can verify connectivity using the ping command. In addition to confirming connectivity, ping tells you the minimum, average, and maximum times for packets making the roundtrip to the target system and back. You can assess the path’s reliability using this command:
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
    Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
    The trace command can be used to view the actual routes that packets take between devices:
    Type escape sequence to abort.
    Tracing the route to
    4 msec 4 msec 4 msec
    Getting Information About Remote Devices Summary
  • Telnet allows remote connections to distant devices.
  • You open a Telnet session by entering the telnet or connect command, followed by the target device’s IP address or host name.
  • The show sessions command displays a list of connected hosts, their IP addresses, their byte counts, the idle time, and the session name.
  • Use the show user command to list all active Telnet sessions.
  • To reestablish a suspended Telnet session, press the Enter key, use the resume command(for the most recent session), or use the resume session number command.
    (Use show session to get session numbers.)
  • The ping and trace commands can be used to obtain information about network devices and to check for connectivity.

    We hope you found this Cisco certification article helpful. We pride ourselves on not only providing top notch Cisco CCNA exam information, but also providing you with the real world Cisco CCNA skills to advance in your networking career.