NET4009_Module 2 - Tshooting EIGRPv4v6

How does EIGRP establish neighbor relationships for IPv4?

sending hello packets to the multicast address 224.0.0.10

What are some reasons that EIGRP neighbor relationships might not form?

1. Interface is down

2. Mismatched autonomous system numbers

3. Incorrect network statement

4. Mismatched K values

5. Passive interfaces

6. Different subnets

7. Authentication

8. ACLs - could be blocking multicast address 224.0.0.10

9. Timers - Could be mismatched but if not configured correctly it could flap

Command to debug mismatched as numbers?

dubug eigrp packets

Command to show incorrect network statements?

show ip eigrp interfaces

Command to see mismatched K Values

show ip protocols

What K values are enabled by default?

K1 and K3 (bandwidth and delay respectively)

What does passive interface do for EIGRP?

• reduces the EIGRP-related traffic on a network

• Improves EIGRP security

What command can be used to see if the wrong interface is set as passive?

show ip protocols

What is the simplest way to troubleshoot different subnets?

look at the interface configuration in the running config (show run interface int_type int_num)

What is authentication used for in EIGRP?

used to ensure the EIGRP routers form a neighbor relationship only with legitimate routers.

Command to verify weather EIGRP authentication is enabled or not?

show ip eigrp interfaces detail int_type int_num

Command to verify the correct keychain that will be used?

show key chain

It is not mandatory that the key ID in use and the key string in use between neighbors match (True/False)

False

EIGRP timers have to match (True/False)

False. Although EIGRP timers do not have to match, if the timers are skewed enough the adjacency will flap

How to verify the timers?

show ip eigrp interfaces detail

What are the reasons for there being missing EIGRP routes?

1. Bad or missing network command

2. Better source of information

3. Route filtering

4. Stub configuration

5. Interface is shut down

6. Split horizon

How to fix the route if there is a better route available?

Adjust the AD (Admin Distance). EIGRP wins by default over OSPF since the AD is lower.

How to show the route filtering?

show ip protocols

EIGRP Stub

allows an admin to conrol the scope of EIGRP queries in the network

How to configure EIGRP stub on a router?

eigrp stub command

Command to show if a router is stub or not?

show ip protocols

How to confirm if the neighbor is a stub router?

show ip eigrp neighbors detail

Split Horizon

routes learned inbound on an interface will not be advertised out the same interface. Prevents routeing loops

Command to verify weather split horizon is enabled on an interface?

show ip interface int_type int_num

What command should be used when there is a discontinuous network within the network?

no auto-summary

What command shows weather automatic summarization is enabled?

show ip protocols

Route Summarization

when a summary route is created on a router a summary route to Null 0 is created

What AD does the route to Null 0 have?

5

What are the two ways EIGRPv6 can be configured?

1. classic AS mode

2. Named mode

How are EIGRP packets identified?

using protocol ID 88 for both IPv4 and v6

What commands are used to display EIGRPv6 configurations

Same commands as ipv4

EIGRPv6 Neighbor Issues

1. Mismatched AS numbers

2. Mismatched K Values

3. Passive Interfaces

4. Mismatched Authentication

5. ACLs

How is EIGRPv6 enabled for an interface?

ipv6 eigrp AS_num
it is enabled automatically on all interfaces

How can ACLs effect EIGRPv6?

could deny packets to the multicase address FF02::A

How to troubleshoot Interfaces not participating in the routing process?

show ipv6 eigrp interfaces

When configuring the named process for EIGRPv6 all the IPv6-enabled interfaces immediately start participating in routing (True/False)

True

How to disable the routing process on an IPv6 interface when using named mode EIGRPv6

the interface needs to be shut down in af-interface configuration mode
This also applies to IPv4 address family

The show commands are the same for classic and named mode EIGRPv6 (True/False)

False

command to verify interfaces for named EIGRP mode?

show eigrp address-family ipv4/ipv6 interfaces
passive interfaces do not show up in this command

command to verify neighbors for named EIGRP?

show eigrp address-family ipv4 ipv6 neighbors