Technology
Configure and Troubleshoot IP Routing
Protocols - EIGRP & OSPF
Process
Cisco
Support
Community
Manas R Moothedath
Sumit Kothiyal
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Cisco Confidential
1
IP Routing Protocols – Part 2
EIGRP
Manas Moothedath and Sumit Kothiyal
Cisco Systems (India) Pvt Limited
26th Mar 2014
EIGRP
AGENDA

EIGRP packets – a quick recap

Basic troubleshooting of EIGRP issues.

A closer look at typical EIGRP error messages

Practical view of EIGRP failure scenarios

Best practices in EIGRP
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EIGRP Packets – A Quick Recap
-
The Hello
Hello
R1
R2
Hello
Network command
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ENABLES EIGRP.
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EIGRP Packets – A Quick Recap
-
The Update
Update
R1
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R2
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EIGRP Packets – A Quick Recap
Reply
R3
-
The Query
-
The Reply
X
R1
R2
Query
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Troubleshooting EIGRP – Effect to cause…
Typical EIGRP error messages – neighborship flapping continuously:
a) EIGRP Hold time expired
b) Retry Limit Exceeded
a) Peer restarted
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The EIGRP – STUCK IN ACTIVE
Revisiting the EIGRP
Query
“show ip eigrp topology active”
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Understanding the ‘EIGRP Topology’
router B# show ip eigrp topology 170.16.0.0 255.255.0.0
IP-EIGRP topology entry for 172.16.0.0/16
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 3757056
Routing Descriptor Blocks:
12.1.2.2 (Serial1), from 12.1.2.2, Send flag is 0x0
Composite metric is (3757056/3245056), Route is External
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 82000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 7
External data:
Originating router is 192.168.1.1
AS number of routes is 0
External protocol is OSPF, external metric is 64
Administrator tag is 0
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Typical EIGRP Failures scenarios:
1. One way link
1. Mismatched Parameters
1. Query boundary too large
Hello
1. Duplicate router-id
ping 224.0.0.10
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EIGRP Caveats:
Discontiguous
Classful Boundary
1. auto-summary
• Enabled/Disabled?
2. Redistribution metric into EIGRP
• MUST be specified
192.168.1.0/24
172.16.1.0/24
3. Routes advertised to a neighbor
1. Only if EIGRP in Routing Table
2. Only the best routes
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172.16.2.0/24
172.16.3.0/24
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OSPF
AGENDA
 OSPF
Hello
 OSPF
Neighborship States
 Troubleshooting
Neighborship Issues
 Common
Misconceptions
 Common
Issues.
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OSPF Hello
• Hello Interval
• Dead Interval
• Subnet Mask
• Area ID
• Authentication
• Optional Capabilities - eg. Stub
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Neighborship states
• Down
• INIT - Initiated (Multicast)
• 2-WAY - See ourself in the neighbor Hello (Multicast)
• Exstart - Master/Slave (Unicast)
• Exchange - Exchanging DBD (Unicast)
• Loading - LSR - LSU - Exchange LSA’s (Unicast)
• Full
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Lab Topology:
R4
R2
R1
R5
R3
R6
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R7
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Neighborship Issue
Neighbor not seen –
• Hello Parameters mismatch.
• Multicast Issues.
Neighbor stuck in Exstart –
• MTU mismatch.
• Unicast Issue.
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Common Caveats:
• Summary LSA is not summarisation.
• Distribute-list out doesn’t work.
• Checking the LSA in the wrong database
(checking intra-area route in show ip ospf database)
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Other issues:
• 2-way with all the neighbors (no DR)
• Not full will all the neighbors
• expected, DR-BDR are full with all the neighbors.
• DROthers are only full with DR-BDR
• Advertising router is not reachable (not pingable)
could be expected if RID is not advertised.
- RID is just a name.
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Thank you.