1. Cisco 2 - Routers Perrine. J Page 110/5/2015 Chapter 4 Cisco Discovery Protocol (CDP) CDP is a layer 2 protocol. CDP is used to: obtain information about neighboring devices types of devices (switch, type of router) router interfaces they are connected to interfaces used to make the connection ( E0, S0, etc.) model number of the devices CDP is protocol independent, and runs on Cisco equipment over the Subnetwork Access Protocol (SNAP).

2. Cisco 2 - Routers Perrine. J Page 210/5/2015 Chapter 4 Cisco Discovery Protocol (CDP) Primary use of CDP is to discover all Cisco devices that are directly connected to a local device. This is done by transmitting type length values (TLVs) which are blocks of information embedded in CDP advertisements. To display the CDP information, use the command: show cdp neighbors

3. Cisco 2 - Routers Perrine. J Page 310/5/2015 Chapter 4 Cisco Discovery Protocol (CDP) Device TLVs displayed by the show cdp neighbors include: device ID local interface holdtime capability platform port ID VTP Management Domain Name (CDPv2* only) Native VLAN (CDPv2 only) Full/Half-Duplex (CDPv2 only) * Supported by Cisco IOS release 12.0(3)T or later

4. Cisco 2 - Routers Perrine. J Page 410/5/2015 Chapter 4 Cisco Discovery Protocol (CDP) To enable CDP globally: cdp run CDP is globally enabled by default. To enable CDP on a particular interface, do: cdp enable On Cisco IOS Release 10.2 or higher, CDP is enabled by default

5. Cisco 2 - Routers Perrine. J Page 510/5/2015 Chapter 4 Cisco Discovery Protocol (CDP) NOTE: 1.Disable CDP at the global level, use no cdp run 2.If CDP is disabled globally, individual interfaces cannot be enabled for CDP 3.IOS Release 10.3 or higher, CDP is enabled by default. However, on asynchronous interfaces, CDP is disabled by default. 4.To disable CDP on a specific interface after it has been enable, do no cdp enable

6. Cisco 2 - Routers Perrine. J Page 610/5/2015 Chapter 4 Telnet Telnet is a virtual terminal protocol that is part of the TCP/IP protocol suite. Provides a remote login capability. Telnet function at the application layer. If a telnet command is successful from one device to another, then all 7 layers of the OSI model is ‘working’. It is the most complete testing mechanism available, say Cisco. Telnet uses the five (5) vty sessions. However, there has to be a ‘login’ and password associated with the vty session in order for telnet to work.

7. Cisco 2 - Routers Perrine. J Page 710/5/2015 Chapter 4 Telnet If one has a ‘host table’ on the router ( ip host ), then you can do telnet. As an example: telnet routerB DUE THE LABS FOR resuming and suspending SESSION. NOTE: 1.Enter command, you go to the most recent session 2.To resume a session it needs a connection ID.

8. Cisco 2 - Routers Perrine. J Page 810/5/2015 Chapter 4 Ping Ping command is used to determine if a particular ip address is reachable. Traceroute command is used to trance the route to an ip address. Ping sends ICMP echo request messages and receive an echo reply. Ping Command CodeExplanation !ICMP echo reply received.Nothing received UICMP unreachable (destination) received NICMP unreachable (network) received PICMP unreachable (port) received

9. Cisco 2 - Routers Perrine. J Page 910/5/2015 Chapter 4 Interface Protocol Serial is up, line protocol is upoperational Serial is up, line protocol is downConnection problems (L2) Serial is down, line protocol is downInterface problems (L1) Serial is administratively down, line protocol is downdisabled

10. Cisco 2 - Routers Perrine. J Page 1010/5/2015 Chapter 4 Interface Protocol For serial port: Serial is up, line protocol is down maybe caused by: network mismatched clock rate not set on DCE mismatch of encapsulation (HDLC vs. PPP)