CCNP TSHOOT 6.0 - Cisco Learning Home

CCNPv6 TSHOOT
Sample Route Redistribution
Troubleshooting Flow
Layer 3
problem
caused by
suboptimal
or incorrect
routes
Verify route
selection and
installation
Locate
source of
incorrect
information
Investigate routing
table and routing
protocol data
structures
Filter or
manipulate
redistributed
routes
Change
administrative
distance or
implement route
filtering
© 2009 Cisco Systems, Inc. All rights reserved. TSHOOT v1.0—89
The first question to ask at this point is if the route is only improperly selected. In other words, you expected this
route to be present but did not want it to be selected as the best route. If this is the case, you can manipulate the
route selection process by changing the administrative distance. This can be done for all routes learned via a
particular routing protocol or selectively using an access list.
If the route was not only improperly selected but should not have been present at all in the routing protocol data
structures in this router, you must track the source of the route and use route-filtering techniques at the source to
stop it from being advertised.
Verify the Routing Table
R1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 15 subnets, 3 masks
O IA 10.1.10.0/24 [110/2] via 10.1.2.1, 07:43:07, FastEthernet0/1
O 10.1.2.12/30 [110/3] via 10.1.2.1, 07:42:57, FastEthernet0/1
C 10.1.1.2/32 is directly connected, Serial0/0/0
C 10.1.2.0/30 is directly connected, FastEthernet0/1
C 10.1.1.0/30 is directly connected, Serial0/0/0
O IA 10.1.30.0/24 [110/2] via 10.1.2.1, 07:43:07, FastEthernet0/1
O IA 10.1.20.0/24 [110/2] via 10.1.2.1, 07:43:07, FastEthernet0/1
O IA 10.1.50.0/24 [110/2] via 10.1.2.1, 07:43:07, FastEthernet0/1
O IA 10.1.100.0/24 [110/2] via 10.1.2.1, 07:43:07, FastEthernet0/1
D 10.1.202.1/32 [90/2297856] via 10.1.1.2, 07:43:48, Serial0/0/0
O IA 10.1.203.1/32 [110/4] via 10.1.2.1, 07:42:57, FastEthernet0/1
C 10.1.201.1/32 is directly connected, Loopback0
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