1. DHCP

2. Accessing Remote Devices

3. Accessing Remote Devices Topics
Cisco Discovery Protocol (CDP)
Telnet
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Purpose: This slide state the objectives
Emphasize: Discuss the objectives with the students.

4. Cisco Discovery Protocol
Upper-Layer Entry Addresses
TCP/IP
Novell IPX
AppleTalk
Others
Cisco Proprietary
Data-Link Protocol
CDP discovers and shows information about directly connected Cisco devices
Media
Frame Relay
LANs
ATM
Others
A data-link proprietary protocol that provides information about directly connected Cisco switches, routers, and other devices
CDP discovers neighbor devices regardless of which protocol suite they are running
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Purpose:
Emphasize:
Note: CDP is sent using multicast frame with the MAC address ccc.cccc.

5. Discovering Neighbors with CDP
Runs on routers with Cisco IOS or later and Cisco switches and hubs
Summary information includes:
Device identifiers
Address list
Port identifier
Capabilities list
Platform
CDP
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Purpose:
Emphasize: CDP is media- and protocol-independent and runs on all Cisco-manufactured equipment including routers, access servers, switches and some managed hubs. With CDP, network management applications can retrieve the device type and SNMP agent address of neighboring devices. This capability enables applications to send SNMP queries to neighboring devices.
CDP allows network management applications to dynamically discover Cisco devices that are neighbors. CDP runs on all media that support Subnetwork Access Protocol, including LAN and Frame Relay. CDP runs over the data link layer only, not the network layer. Therefore, two systems that support different network-layer protocols can learn about each other.
Cached CDP information is available to network management applications. Cisco devices never forward a CDP packet. When new information is received, old information is discarded. The holdtime determines how long to keep existing information from a neighbor.
CDP
CDP
show cdp

6. Using CDP SwitchA RouterA RouterB SwitchB S1 S0 10.1.1.2 10.1.1.1
RouterA#sh cdp ?
entry Information for specific neighbor entry
interface CDP interface status and configuration
neighbors CDP neighbor entries
traffic CDP statistics
<cr>
RouterA(config)#no cdp run
RouterA(config)#interface serial0
RouterA(config-if)#no cdp enable
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Purpose:
Emphasize:
Note: Some of the CDP commands are not available on the Cat 1900 switch, like “cdp run”, “show cdp traffic”, and “show cdp entry”.

7. Using the show cdp neighbor Command
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#sh cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
RouterB Ser R Ser 1
SwitchA Eth T S
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Purpose:
Emphasize: This graphic shows the show cdp neighbors command initiated from a router, which displays a summary of the capabilities and access details for the CDP neighbors. The show cdp neighbors detail command shows detailed information about the same devices.
Note: If the neighbor is a Cat 1900 switch, the switch mac address is also displayed. If the switch is a 2900xl, its mac address is not displayed.

8. Using the show cdp entry Command
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#sh cdp entry *
Device ID: RouterB
Entry address(es):
IP address:
Platform: cisco 2522, Capabilities: Router
Interface: Serial0, Port ID (outgoing port): Serial1
Holdtime : 168 sec
Version :
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fci)
Copyright (c) by cisco Systems, Inc.
Compiled Mon 08-Feb-99 18:18 by phanguye
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Purpose:
Emphasize: The example shows what information can be obtained about RouterA’s neighbor. CDP is one way to learn about other Cisco devices on the network.

9. Additional CDP Commands
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#sh cdp traffic
CDP counters :
Packets output: 56, Input: 38
Hdr syntax: 0, Chksum error: 0, Encaps failed: 3
No memory: 0, Invalid packet: 0, Fragmented: 0
RouterA#sh cdp interface
BRI0 is administratively down, line protocol is down
Encapsulation HDLC
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
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Purpose:
Emphasize:
Note: The holdtime indicates how long the neighbor information will be kept in the local CDP table.

10. Using Telnet to Connect to Remote Devices
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#telnet
Trying Open
Catalyst 1900 Management Console
Copyright (c) Cisco Systems, Inc
All rights reserved.
Enterprise Edition Software
Ethernet Address:
PCA Number:
PCA Serial Number: FAA02359H8K
Model Number: WS-C1924-EN
System Serial Number: FAA0237X0FQ .
SwitchB>
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Purpose:
Emphasize: Another way to learn about a remote device is to connect to it. Telnet, a virtual terminal protocol that is part of the TCP/IP protocol suite, allows connections to remote hosts. By default, a router can have up to five simultaneous incoming Telnet sessions. With Cisco’s implementation of TCP/IP, you need not enter the connect or telnet command to establish a Telnet connection. If you prefer, you can just enter the learned host name, the router will resolve the hostname using DNS or a local host table. To end a Telnet session, use the exit or logout EXEC command.
These are alternate commands for the operations listed on the graphic:
Initiate a session:
Denver> connect paris
Denver> paris
Denver>
Resume a session (enter session number or name):
Denver> 1
Paris>
End a session:
Paris> exit
Note: The Cat 1900 can accept incoming telnet connections but can not initiate an outgoing telnet session.
Remote device

11. Viewing Telnet Connections
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#sh session
Conn Host Address Byte Idle Conn Name *
RouterA#sh user
Line User Host(s) Idle Location
* 0 con
11 vty idle
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Purpose:
Emphasize:
Note: This output was taken from a Line 11 = VTY 0.
You can send messages to one or all terminal lines. A common reason for doing this is to inform users of an impending shutdown. To send a message to other terminals, issue the following command:
send {line-number | *}
Syntax Description
line-number Specifies the line number to which the message will be sent.
* Indicates that the message will be sent to all lines.
The system prompts for the message, which can be up to 500 characters long. End the message by entering Ctrl-Z. Enter Ctrl-C to abort the command.

12. Suspending a Telnet Session
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterB#<Ctrl-Shift-6>x
RouterA#sh session
Conn Host Address Byte Idle Conn Name
RouterA#resume 1
RouterB#
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Purpose:
Emphasize: The key stoke sequence for Ctrl-Shift-6 and x.

13. Closing a Telnet Session
SwitchA
RouterA
RouterB
SwitchB S1 S0
RouterA#disconnect
Closing connection to [confirm]
RouterA#clear line 11
[confirm]
[OK]
Closing the current session opened by you to a remote device
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Purpose:
Emphasize:
Note: Disconnect without the session number disconnect that last active session.
Closing a session opened by a remote device to you

14. Using the ping and trace Commands
Router##ping
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
Router#trace
Tracing the route to
msec 4 msec 4 msec
Router#
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Purpose:
Emphasize: As you use CDP and Telnet you should note the information retrieved from the devices you successfully contacted. Documenting that information helps put the network into a visual perspective, and can be referenced at a later time.
This concludes the network discovery portion of the chapter. In the next section, we will discuss configuration file and IOS image management.
Test connectivity and path to a remote device

15. Review Questions
1. What CDP command is used to get information about one specific neighbor?
2. What key combination suspends a Telnet session?
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Purpose:
Emphasize: Refer to the appendix for the answers to the review questions.