Post on 02-Jun-2018
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Department of Computer and Systems Engineering
Introduction
CDP and Telnet
Enable and disable CDP Establish a Telnet connection
Verify a Telnet connection
Disconnect from a Telnet session
Suspend a Telnet session
Perform alternative connectivity tests Ping
Traceroute
Show ip route
Show interface
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CS341: LEARNING ABOUT OTHER DEVICES
Department of Computer and Systems Engineering
Cisco Discovery Protocol Layer 2 protocol that connects network and physical layer to obtain information about
neighboring devices
When a Cisco device boots up, CDP starts up automatically and allows the device todetect neighboring devices that are also running CDP.
It runs over the data link layer and allows two systems to learn about each other, even
if they are using different network layer protocols.
Each device configured for CDP sends periodic messages, known as advertisements,to multiple routers.
Each device advertises at least one address at which it can receive Simple Network
Management Protocol (SNMP) messages.
The advertisements also contain time-to-live or holdtime information, indicating thelength of time that receiving devices should hold CDP information before discarding it.
Additionally, each device listens to periodic CDP messages sent by others in order to
learn about neighboring devices.
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CS341: LEARNING ABOUT OTHER DEVICES
Department of Computer and Systems Engineering
CDP CDP learns:
Type of devices connected
Router interfaces they are
connected to
Model number of the devices
CDP is media and protocol independent
but runs only on Cisco devices
Router(config)#cdp run
enables CDP globally on the
router Router(config-if)#cdp enable
enables CDP on an specific
interface.
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Implementation, monitoring, andmaintenance of CDP
Router#show cdp
Router#show cdp neighbors
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Department of Computer and Systems Engineering
Telnet Virtual terminal protocol that can be used to
verify the application layer software between
host and source.
Verify the application-layer software between
source and destination stations.
Most complete test of connectivity.
Router can have up to 5 incoming telnetsessions ( 0 to 4).
May use command telnet, connect,
hostname(if DNS or host table is available),
or IP address to connectrouter>router>connectconnectparisparis
router>router>parisparis
router>router>131.108.100.152131.108.100.152
router>router>telnettelnetparisparis
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Department of Computer and Systems Engineering
Telnet Suspending a
Telnet session is
Press Ctrl-
Shift-6, then
x
Show sessions
displays listof current
telnet
sessions
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Department of Computer and Systems Engineering
Telnet Telnet can be used to perform a test to determine whether or not a remote router can be
accessed.
If Telnet is used successfully to connect the York router to the Paris router, then a basic
test of the network connection is successful.
This operation can be performed at either the user or privileged EXEC levels.
If remote access can be obtained through another router, then at least one TCP/IP
application can reach the remote router.
A successful Telnet connection indicates that the upper-layer application functions
properly
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Department of Computer and Systems Engineering
Ping Ping- uses an Echo protocol to
test connectivity, delay and if
destination is functioning. The ping user EXEC command
can be used to diagnose basicnetwork connectivity.
The command ping uses ICMP
ping ip address or hostname
! -means successfulreciept
. means timed out Udestination
unreachable
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Traceroute
The traceroute
command is the idealtool for finding where
data is being sent in a
network.
traceroute tests each
step along the way.
This operation can be
performed at either the
user or privileged
EXEC levels.
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Department of Computer and Systems Engineering
PING/TELNET/TRACEROUTEping
uses the ICMP protocol to verify the hardwareconnection and the IP address of the network layer. This
is a basic testing mechanism.
telnet
verifies the application layer software between source
and destination. This is the most complete test
mechanism available.
traceroute allows the location of failures in the path from the source
to the destination. Trace uses Time to Live values to
generate messages from each router along the path.
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Show ip route
Show ip route
show the routing table, and how the routes were learned
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Show interfaces
Show interfaces serial
show serial connections status