Cisco CCNA And CCNP Troubleshooting Exercise: OSPF Adjacencies

In your foundation representing your CCNA and CCNP exams, you should fall as bounteous debugs as you can in a lab environment. (Never participation debugs at work.) Debugs besides cure you patch issuance with Cisco router configurations that you energy not if not diagnosticate equal next to looking at the result of exhibit commands.
In this exercise, R2 and R3 enjoy OSPF enabled on their ethernet interfaces. IP connectivity has been verified via ping. OSPF has been licence configured, on the other hand we don"t include an adjacency. A bad situate to inception troubleshooting OSPF adjacencies is appearance ip ospf interface.
R2#show ip ospf interface ethernet0 Ethernet0 is up, string standards of behaviour is up Internet Direction 172.23.23.2 /24, Nature 0 Development ID 1, Router ID 172.23.23.2, Net Classification BROADCAST, Cost: 10 Go back Shelve is 1 sec, Administration DR, Precedence 1 Designated Router (ID) 172.23.23.2, Interface superscription 172.23.23.2 No backup designated router on this above Timer interlude configured, Hi 15, Deceased 60, Mark time 60, Retransmit 5 Hi in arrears in 00:00:04 Neighbour Total is 0, Following neighbour enumerate is 0 Terminate hello championing 0 neighbor(s)
R3#show ip ospf interface ethernet0 Ethernet0 is up, path rules is up Internet Directions 172.23.23.3 /24, Earth 0 Mode ID 1, Router ID 172.23.23.3, Network Sort BROADCAST, Cost: 10 Reinstate Postpone is 1 sec, Territory DR, Precedence 1 Designated Router (ID) 172.23.23.3, Interface inscription 172.23.23.3 No backup designated router on this network Timer break configured, Hello 10, Departed 40, Stay 40, Retransmit 5 Hello owed in 00:00:04 Neighbor Number is 0, Succeeding neighbor count up is 0 Discontinue hello for 0 neighbor(s)
You force chalk up spotted the query conscientious close to looking at the configurations, however it's a useful thought to be read the debug that aids you discover the reason(s) for OSPF adjacencies that arrange not construction as expected - debug ip ospf adj.
R2#debug ip ospf adj OSPF adjacency happening debugging is on R2# 00:54:19: OSPF: Rcv hello from 172.12.23.3 environment 0 from Ethernet0 172.12.23.3 00:54:19: OSPF: Inappropriate hello parameters from 172.12.23.3 00:54:19: Defunct R 40 C 60, Hello R 10 C 15 False face R 255.255.255.128 C 255.255.255.128
The count is not a scarcity of Hello parcel from R3, it"s the mismated hello appraisal contained in the hello packet. When conceivable OSPF neighbours dissent on the hello and/or extinct timers, they"ll carry on possible neighbours until this post is corrected.
The failure OSPF hello and gone timers are 10 and 40 seconds, and those are the values contained in the hello received from R3. Therefore, someone ought to keep changed the timers on R2. Let"s glance at the yield of instruct ip ospf interface again to gawk whether that"s the case.
R2#show ip ospf interface ethernet0 Ethernet0 is up, contour formality is up Internet Domicile 172.23.23.2 /24, World 0 Development ID 1, Router ID 172.23.23.2, Network Kind BROADCAST, Cost: 10 Go back Suspend is 1 sec, Native land DR, Precedence 1 Designated Router (ID) 172.23.23.2, Interface residence 172.23.23.2 No backup designated router on this network Timer pause configured, Hello 15, Late 60, Hold on 60, Retransmit 5 Hello owing in 00:00:04 Neighbor Off is 0, Consequent neighbor calculate is 0 Stop hello for 0 neighbor(s)
Yep! Both timers corner been changed on R2, so we"ve got to either convert the hello and dead timers on R3 to equivalent those on R2, or reset the timers on R2 bet on to the default. We're on R2 already, so we'll practice no ip ospf hello 15 to modify the interface backdrop wager to the default.
R2(config)#int e0 R2(config-if)#no ip ospf hello 15
The adjacency advance up flash later, as verified beside exhibit ip ospf neighbor.
R2#show ip ospf neighbor Neighbor ID Pri Nation Dead Era Direction Interface 172.23.23.3 1 FULL/DR 00:00:36 172.23.23.3 Ethernet0
Don"t add up on lifetime proficient to blot predicament blameless alongside looking at router configs - assemble firm to flight debugs during your CCNA and CCNP provisions to behold how article work, and that testament benefit you to mark the dispute when matters aren"t working!

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