connections to the Other Router

Cisco Discovery Protocol (CDP) is a useful tool to overcome the incomplete or inaccurate network. CDP is media and protocol independent, CDP only displays information about the nearest neighbor router connection. Diharapan after the module is able to:

• Enable and disable CDP
• Understanding the command show cdp neighbors
• Determine which neighboring devices are connected to the respective local interface
• Obtain information about neighboring devices using CDP
• Create a connection to the router via telnet
• Verify the connection via telnet
• Diskonek of telnet
• Testing performance connectivity
• Troubleshoot remote terminal connections

1. CDP
CDP is a layer 2 protocol that connects to the Medi physical and network layer protocols, as shown by figure 1.1.

Figure 1.1 CDP

CDP is used to obtain information about the cisco neighbors, such as information about the type of device that is connected, the connected interface, the interface used to connect devices and the number of models. CDP is media and protocol independent, and the road above the Subnetwork Access protocol (SNAP).

CDP version 2 (CDPv2) is the latest version. Cisco ios release 12.0 (3) T or later CDPv2 use, while the default CDPv1 enable the Cisco ios release 10.3 to 12.0 (3) T.

When the device cisco boot up, CDP automatically start and devices to perform detection devices that use CDP neighbors. CDP operates at the data link layer and leave the system to learn tetangganay, although using a different protocol layer.

Each device is configured for CDP sends periodic messages, known as advertisement to cisco device that is connected directly. Individual advertise at least one address that received the message Network Management Protocol (SNMP). Advertisement also includes a time-to-live, or holdtime information that determines the length of the devices receive CDP information before Discard information. Each device is listen periodic CDP messages sent by neighboring devices.
Information about the cisco neighbors

To find out more about the cisco connected directly use the command show cdp neighbors. Figure 1.2 is an example of how CDP gather information about the cisco is connected directly. Send CDP type length values (TLVs) to provide information about each CDP neighbor device. Show cdp neighbors to provide information on:

• ID of the device
• Local Interface
• Holdtime
• Capacity
• Platform
• Port ID

TLVs and information that is only found in the CDPv2 is:

• VTP Domain name management
• Native VLAN
• Full or half duplex

Figure 1.2 show cdp neighbors

Figure 1.3 show cdp neighbors

Commands CDP

• cdp run
• cdp enable
• show cdp traffic
• clear cdp counters
• show cdp
• show cdp entry (* | device-name [*] [protocol | version])
• show cdp interface [type number]
• show cdp neighbors [type number] [detail]

Cdp run command is used to enable CDP globally on the router. By default CDP enable conditions. Cdp enable command is used to enable men-kan-CDP.

Figure 1.4 the clear cdp counters



Figure 1.5 show cdp command



Figure 1.6 show cdp entry command




Figure 1.7 show cdp interface command




Figure 1.8 show cdp neighbors command

Design and implementation of the CDP is sederhan, low-overhead protocol. Through the CDP of the frame is very small and can receive a lot of useful information about the cisco device that is connected directly.

Information can be used to create a map of network devices that are connected directly. To find the device that is connected to the neighboring router, and then use the command show cdp neighbors.

Disable CDP
CDP can be disable with two level:

• Using the no cdp run commands that are used in the global config. This command is used when only one device cisco CDP and run if there will be no use.
• CDP can be disable from a particular interface. By using the command no cdp enable or no cdp advertise-v2-based version of CDP used.

Figure 1.9 disabling CDP

Figure 1:10 the CDP troubleshooting

2. Basic Router and routing

Telnet
Telnet is a virtual terminal protocol that is part of TCP / IP. Telnet is used for the remote host that is used to verify the application layer between the origin and destination. Telnet function on the application layer OSI layer. Telnet depending on the TCP to menggaransi data between the client and server.

Figure 2.1 telnet application layer to operate

The user can telnet to the remote from one another cisco to cisco. Hostname or IP address must be known to be able to perform remote telnet meggunakan. And to exit from the telnet session use the command logout or exit. For the telnet session can be done as follows:

Denver> connect paris
Denver> paris
Denver> 131108100152

Denver> telnet paris

Figure 2.2 telnet working

If you telnet to a router succeed, the router failed to address other error or access problems. The next step is to use the ping command to perform that function testing connection.

Figure 2.3 application layer testing

To find out where the telnet session is active digunaka show sessions command. The procedures used to diskonek telnet session as follows:

• Enter the disconnect command 􀁗
• followed by the hostname or IP address, eg: Denver> disconnect paris
  

Procedure that is used to exit from telnet:

• Press the Ctrl-Shift-6, then x
• Enter the hostname or IP address

Figure 2.4 telnet working

Testing connection with the PING
Traceroute command can be used to find where data is sent to the network. This command is similar to the ping command. Basic difference, if the ping for testing connectivity from end-to-end connectivity while traceroute tests each step the data.

If one of the router that passed unreachable, it will show signs 3 asterisk (*). To view the routing table on the router can use the command show ip route.
Below is a procedure using the ping command:

• Enter the command ping followed by the IP address or hostname of destination
• Press the ENTER

Meanwhile, to use the traceroute command:

• Enter the traceroute command followed by the IP address or hostname of destination
• Press the ENTER

Figure 2.5 testing connectivity with the ping command

Figure 2.6 connectivity testing with the command traceroute

• Ping - use the ICMP protocol to verify mem-connection hardware and IP address from the network layer
• Telnet - mem-verification application software layer between the source and destination
• Traceroute - failure to provide a location between the source and destination

Figure 2.7 IP address troubleshooting