Learning about Neighboring and Remote Devices PJC CCNA Semester 2 Ver. 3.0 by William Kelly

Cisco Discovery Protocol (CDP) Basics CDPs primary purpose is to discover all directly connected Cisco devices CDPs primary purpose is to discover all directly connected Cisco devices CDP is a layer 2 protocol linking physical layer and upper layer protocols CDP is a layer 2 protocol linking physical layer and upper layer protocols CDP provides info. about connected devices, the model number of those devices, and the connected interfaces CDP provides info. about connected devices, the model number of those devices, and the connected interfaces CDP is a Cisco proprietary protocol CDP is a Cisco proprietary protocol CDP is media and protocol independent (can learn info. even if other devices use different protocols) CDP is media and protocol independent (can learn info. even if other devices use different protocols) CDP v2 is the most recent release and runs on IOS 12.0(3) and later CDP v2 is the most recent release and runs on IOS 12.0(3) and later

Common CDP Commands

Info. from show cdp neighbors Command Device ID Device ID Address Address Port ID Port ID Capabilities Capabilities Version Version Platform Platform IP Network Prefix IP Network Prefix VTP Management Domain Name (CDPv2 only) VTP Management Domain Name (CDPv2 only) Native VLAN (CDP v2 only) Native VLAN (CDP v2 only) Full/Half-Duplex (CDPv2 only) Full/Half-Duplex (CDPv2 only)

Overview of Testing

Telnet and Advanced Telnet Telnet is used to verify the application layer between the source and the destination A router can have 5 simultaneous telnet sessions (vty 0 – 4) Telnet depends on the TCP to accurately deliver the data Ctrl + Shift + 6 followed by hitting the letter x will escape the current telnet session The show sessions command will display all the current telnet sessions The resume session# will resume a particular telnet session

Alternate Connectivity Tests ping traceroute show ip route show interfaces serial show interfaces/clear counter debug

The ping Command Ping is an echo protocol that helps evaluate path reliability Ping is used to troubleshoot lower level OSI connectivity The basic ping can be used in both the user and privileged mode

Ping Return Codes

The traceroute Command Traceroute follows the route data travels through a network and can be used to find broken network connections (broken end to end connectivity) Traceroute can be used at the user and privileged level Traceroute operates by sending pings with ever increasing Time to Live (TTL) values Ctrl-Shift-6 can be used to cancel a traceroute

Traceroute Return Codes

The show ip route Command The show ip route command lists the map the router has constructed to switch packets The output of this command is referred to as the routing table

The show interfaces serial Command The show interfaces serial command displays information about the serial connection between two routers The hardware including cables and interfaces The software including protocols

The states of a serial interface 1.Serial0 is up, line protocol is up – OPERATIONAL 2.Serial0 is up, line protocol is down – CONNECTION PROBLEM 3.Serial0 is down, line protocol is down – INTERFACE PROBLEM 4.Serial0 is administratively down, line protocol is down - DISABLED

Debug Commands Debug all should not be used on a production router as it will slow down or crash your network Use debug ? to find the appropriate debug command Use undebug all to turn off all debugging