ccnp4 layer3+troubleshooting

8/4/2019 CCNP4 Layer3+Troubleshooting

1/15

1

1 2003, Cisco Systems, Inc. All rights reserved.

CCNP4

Layer 3 troubleshootingHalmstad University

Olga Torstensson

035-167575 [email protected]


Network Layer Overview


2/15

2


Interior IP Routing


Troubleshooting Static Routes


3/15

3


Troubleshooting Static Routes


Debug ip routing


4/15

4


Common Routing Problems


Isolating the Problem

The first step is to isolate the problem.

Identify and document the symptoms

Some of the things to consider include:Has anything in the network changed recently?

Is there anyone currently working on thenetwork infrastructure?


5/15

5


Troubleshooting Commands

Commands used in this example and some of the commands that canbe used for other routing protocols include:

show ip interface

show ip interface brief

show ip eigrp interfaces

show ip ospf interface

debug ip routing

debug ip rip

debug ip igrp transactions

debug ip eigrp

debug isis adj packets

debug isis update-packets


RIP

Incompatible RIP Version Types

Mismatched Authentication Key

RIP Hop Count Limit

Discontinuous Networks


6/15

6


Troubleshooting EIGRP

Mismatched K Values (K1 for bandwidth , K2for load , K3 for delay , K4 for reliability, K5

for reliability)

Mismatched AS Numbers

Stuck in Active

Duplicate Router IDs


Common EIGRP Errors


7/15

7


Troubleshooting EIGRP

Big showBig show && Big DBig D for EIGRPfor EIGRP

shsh ipip eigrpeigrp neighborsneighbors [ as_number | interface ][ as_number | interface ]

shsh ipip eigrpeigrp topology [as_number | active |topology [as_number | active |pending | summary ]pending | summary ]

showshow ipip protocolsprotocols showshow ipip routeroute

debugdebug ipip eigrpeigrp


Down

Attempt

Init

2Way

Exstart / Exchange

Loading

Full

No info from neighbour

Hello sent no reply

1 side blocking hello packet

Normal on broadcastnetworks

Access list, MTU size

Neighbour sending badpacket

Troubleshooting OSPF - Neighbours

OSPF Neighbour stateOSPF Neighbour state Possible reason for stuck in statePossible reason for stuck in state


8/15

8


Layer 2 down

OSPF no enabled

Passive interface used

Mismatched subnets

Mismatched Hellos/Dead interval

Mismatched authentication

Mismatched Area Ids

Mismatched Area types

Troubleshooting OSPF

Adjacencies not coming up?Adjacencies not coming up?


Troubleshooting OSPF missing routes

Routing protocols

Redistribution

Stub vs NSSA vs Totally stub

Default routes

Summarisation

Route filters

access-lists

Virtual Links


9/15

9


OSPF Mismatched Parameters

Mismatched Hellos/Dead interval

Mismatched authentication

Mismatched Area Ids

Mismatched Area types


External Route Installation Problems


10/15

10


Route Summarisation Problems


show ip ospf database

show ip ospf neighbors

show ip ospf interface show ip ospf

show ip route

debug ip ospf adj

debug ip ospf events

Troubleshooting OSPF

Big showBig show && Big DBig D for OSPFfor OSPF


11/15

11


Common BGP Neighbour Problems

Directly connected EBGP neighbours notinitializing

Non-directly connected EBGP neighbours

not initializing IBGP neighbours not initializing


Directly ConnectedEBGP Neighbor Problems

Directly connected EBGP neighbors notinitializing

Layer 2 is down

incorrect neighbor IP address


12/15

12


Directly ConnectedEBGP Session

AS109 AS110


Nondirectly Connected

Common causes for nondirectlyconnected EBGP neighbors not initializingare:

route to the nondirectly connected peer addressis missing from the routing table.

ebgp-multihop command is missing

update-source interface command is missing


14/15

14


Redistribution Problems with OSPF


Redistribution Problems with BGP


15/15

15


Documentation reviewDefine Problem

Gather Facts

Consider Possibilities

Create Action Plan

Implement Action Plan

Observe results

Fixed ?

Problem Diagnosis How Resolved

Document ProcessYesNo

Troubleshootingtools

'show ...'

'debug ...''logging ...' SiSi


Documentation review

Define Problem

Gather Facts

Consider Possibilities

Create Action Plan

Implement Action Plan

Observe results

Fixed ?

Problem Diagnosis How Resolved

Document ProcessYesNo

Troubleshootingtools

'show ...''debug ...''logging ...' SiSi

RouterA - interfaceS0/0 is shutdown

sh ip interface briefshow running-config

show protocols

No shutdown oninterfaceS0/0.

ccnp4 layer3+troubleshooting

Documents