Module 9 Troubleshooting

Troubleshooting using routing tables Network testing and troubleshooting can be consuming Efficient testing and troubleshooting must be done in a

show ip route show ip route command contains entries for all known networks and subnetworks,

Gateway of last resort AKA Syntax used when the router is ip default-network network establishes a default route in networks using dynamic routing protocols or ip route 0.0.0.0 0.0.0.0 [next-hop-ip-address | exit-interface]

Movement of a pdu from source to destination Both Layer 2 and Layer 3 addresses are used to get packet from source to destination Layer 3 address is used to route the packet from the ________________ _______________________________ L3 addresses never change Layer 2 address is used for __________ _____________________________ L2 addresses change at each hop

Administrative Distance administrative distance is a metric is considered only after the field has been narrowed by

Troubleshooting tips Maintain an orderly process and structure when figuring out the problem ping command is used at _________ to test connectivity. telnet command may be used to verify ___________________________________________________________________ Also used for verification of the application layer software between source and destination

Interpreting “show interfaces” command displays the status and global parameters associated with all interfaces status of two important portions of the interfaces is shown related to the includes cables, connectors and shows the condition of the physical connection between the devices related to shows the state of messages such as ___________ ____________________________________________________________________________________

Show interface cont… Keepalives are defined as messages sent by one network device to inform another network device that the virtual circuit between the two is still active

Other stats provided by “Show int” Increasing number of carrier transitions counts on a serial link may indicate one or more of the following problems: Line interruptions due to problems in the service provider network. Faulty switch, CSU/DSU, or router hardware Increasing number of input errors could mean: Faulty telephone company equipment Noisy serial line Incorrect cable or cable length Damaged cable or connection Defective CSU or DSU Defective router hardware

show ip protocol Command displays values about _____ _______________________________________________________ used to confirm ________________________________ which _________ _______________ which interfaces are sending updates ______________ _______________

show ip protocol cont… also shows timers, filters, route summarization, route redistribution, and other parameters can be used to diagnose a multitude of routing issues Check out all of these when doing labs…

Labs for MOD 9 Troubleshooting Using Ping and Telnet Using show ip route to examine routing tables Troubleshooting routing issues with show ip route and show ip protocols Troubleshooting routing issues with debug Troubleshooting using Trace Route