Week 2: Troubleshooting EIGRP for IPv4/IPv6

Question 1

Which multicast address does EIGRP use for neighbor relationship?

Answer 1

224.0.0.10

Question 2

What are the main reasons for a failed EIGRP neighbor relationship?

Answer 2

1 - Interface is down
2 - Mismatched AS numbers
3 - Incorrect network statement
4 - Mismatched K values
5 - Passive interfaces
6 - Different subnets
7 - Authentication
8 - ACLs (an ACL might deny multicast address)
9 - Timers (they do not have to match; recommended hello timer < (3x) hold timerq

Question 3

What are the debug commands for EIGRP?

Answer 3

debug eigrp packets
show ip eigrp interface
show ip protocols
show run int g0/0
show ip eigrp int detail g0/0
show ip eigrp neighbor
show ip eigrp neighbor detail
show key chain

Question 4

How to troubleshoot EIGRP authentication?

Answer 4

The name of the key does not matter
Make sure that ID and string match

Question 5

What are the main causes behind missing EIGRP routes?

Answer 5

• bad or missing network command
• better source of information
• route filtering
• stub configuration
• interface is shut down
• split horizon

Question 6

What is EIGRP’s split-horizon rule?

Answer 6

It states that any route learned inbound on an interface will not be advertised out the same interface.

Question 7

What is EIGRP’s protocol ID?

Answer 7

88

Question 8

What are the messages sent by EIGRPv6?

Answer 8

• Hello
• Acknowledgment
• Query
• Reply
• Update