Commands

Modules: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | All |

Module 5: Layer 3 Troubleshooting

5.1.2

Isolating the problem methodology

> Router#ping
> Router#traceroute
> Router#show interface
> Router#show ip interface
> Router#debug

5.2.1

Static routes and classful lookups

> Router#ip classless
> Router#show ip route
> Router#debug ip routing

5.3.2

Missing or incorrect network or neighbor statement

> Router#show ip protocols
> Router#show ip interface
> Router#show ip interface brief
> Router#show ip eigrp interfaces
> Router#show ip eigrp neighbors
> Router#show ip ospf neighbor
> Router#show ip ospf interface
> Router#debug ip routing
> Router#debug ip rip
> Router#debug ip eigrp
> Router#debug ip igrp events [ip-address]
> Router#debug ip igrp transactions [ip-address]
> Router#debug ip ospf events
> Router#debug isis adj packets
> Router#debug isis update-packets

5.3.5

Access list blocking

> Router(config)#ip access-group {access-list-number | access-list-name}{in | out}
> Router(config)#debug ip packet

5.3.7

Passive interface

> Router(config-router)#passive-interface {interface-type interface-number}

5.4.7

Large routing tables

> Router(config-router)#ip summary-address rip ip-address ip-network-mask

5.5.5

Candidate default

> Router(config-router)#default-information originate
> Router(config)#redistribute static
> Router(config)#ip default-network

5.6.1

Mismatched K values

> Router(config-router)#metric weights qos k1 k2 k3 k4 k5

5.6.3

Stuck in active-determining the problem

> Router#show ip eigrp topology [active | pending | zero-successors]

5.7.1

Mismatched parameters

> Router#debug ip ospf adj

5.7.5

Forwarding address is not know through the intra-area or inter-area route

> Router(config-router)#area area-id range ip-address mask [advertise | not-advertise] [cost cost]
> Router#show ip ospf database [external]
> Router#debug ip route
> Router(config)#route-map map-tag [permit | deny] [sequence-number]

5.7.6

Route summarization problems

> Router#show ip ospf [process-id] summary-address

5.7.8

SPF Calculation and route flapping

> Router#debug ip ospf monitor
> Router#show log

5.8.1

IS-IS adjacency problems

> Router#show clns area-tag is-neighbors [type number] [detail]
> Router#debug isis adj-packets
> Router#show clns neighbors [detail]

5.8.2

Some or all of the adjacencies are not coming up

> Router(config-router)#is-type [level-1 | level-1-2 | level-2-only]
> Router#debug isis adj-packet

5.8.3

Adjacency is stuck in INIT state

> Router#show clns area-tag is-neighbors [type number] [detail]
> Router#show clns interface
> Router#debug isis adj-packet

5.8.6

Route flapping problem

> Router#show isis area-tag spf-log
> Router#debug isis spf-events
> Router#debug isis spf-triggers
> Router#debug isis spf-statistics
> Router#debug isis update-packet
> Router#debug isis adj-packet

5.9.1

Troubleshooting BGP neighbor relationships

> Router#show ip bpg summary
> Router#show ip bgp neighbors
> Router#debug ip bgp

5.10.2

Redistribution problems with IGRP/EIGRP

> Router(config-router)#neighbor {ip-address | peer-group-name} default-originate [route-map map-name]
> Router(config-router)#default-metric
> Router(config-router)#neighbor {ip-address | peer-group-name} distribute-list {access-list-number | expanded-list-number | access-list-name| prefix-list-name} {in | out}

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