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300-410 Exam - Question 28


Refer to the exhibit. The network administrator configured the branch router for IPv6 on the E 0/0 interface. The neighboring router is fully configured to meet requirements, but the neighbor relationship is not coming up.

Which action fixes the problem on the branch router to bring the IPv6 neighbors up?

Show Answer
Correct Answer: A

The issue is that the administrator must correctly configure the interface for IPv6 OSPFv3. In OSPFv3, it is possible to configure OSPF for both IPv4 and IPv6 address families. However, from the exhibit, it appears that OSPFv3 is configured for the IPv4 address family on the E 0/0 interface (using the command 'ospfv3 4 area 0 ipv4'). To fix this, the administrator should disable the OSPFv3 configuration for the IPv4 address family and properly configure it for IPv6. Thus, the command 'no ospfv3 4 area 0 ipv4' should be issued under the E 0/0 interface to correct the configuration.

Discussion

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amgue
Nov 6, 2021

I don't understand the answer ! the question is about the enabling Ipv6 neighborship, not IPV4 neighborship, can somewone explain this to me PLEASE ?

spapi0390
Nov 23, 2021

With the OSPFv3 address families feature, you may have two device processes per interface, but only one process per AF. If the IPv4 AF is used, an IPv4 address must first be configured on the interface. For IPv6 AF it is enough, if only IPv6 is enabled on the interface, as OSPFv3 uses link-local addresses. A single IPv4 or IPv6 OSPFv3 process running multiple instances on the same interface is not supported.

Jenia1Option: B
Nov 15, 2021

B is the correct answer, but I totally agree with amgue, the question is about IPv6 and not IPv4, although if you configure OSPFv3 like this, you will see LSA type 8/9, so maybe what they meant, but it is interesting why they call it IPv6 as you also will see LSA type 1/2. Appreciate if someone can shed a light on this

spapi0390
Nov 23, 2021

With the OSPFv3 address families feature, you may have two device processes per interface, but only one process per AF. If the IPv4 AF is used, an IPv4 address must first be configured on the interface. For IPv6 AF it is enough, if only IPv6 is enabled on the interface, as OSPFv3 uses link-local addresses. A single IPv4 or IPv6 OSPFv3 process running multiple instances on the same interface is not supported.

wts
Jan 27, 2022

Doesn't "address-family ipv4 unicast" automatically appear under the router after adding an interface to OSPF?

wts
Feb 1, 2022

"The appropriate address family is enabled automatically when OSPFv3 is enabled on an interface.", - cisco official guide.

wts
Feb 1, 2022

(config)#ipv6 unicast-routing (config)#ipv6 cef (config)#router ospfv3 4 (config-router)#router-id 192.168.1.1 (config)#interface GigabitEthernet0/0 (config-if)#ipv6 enable (config-if)#ipv6 ospf neighbor FE80: - this and the previous commands are needed because the ipv6 address is not specified. (config-if)#ospfv3 4 ipv6 area 0 - this command is missing so that the interface participates in ospfv3 ipv6. (this is the correct order of the keywords, the wrong order is given in the question.) To be honest, I do not know what to do if I get a question like this.

Huntkey
Sep 10, 2022

Yes but it doesn't appear in the question so someone deliberately removed it. It shows you the running configuration, not the configuration script you would use to configure it.

toto89
Dec 23, 2022

Yes but I tried to remove the address familly under the OSPFv3 router configuration and it automatically remove OSPFv3 configuration on the interface too. This question is broken, hope they fixed it in the exam.

Azaelyus
Jan 10, 2023

call Miroslav Tihlarik

Azaelyus
Jan 10, 2023

+420725950480

Dacusai
Jul 13, 2022

I think the question is wrong from the beginning, The appropriate address family is enabled automatically, but at least you should have a link local address for the relation to form.

examSharkOption: B
Aug 6, 2021

The given answer is correct router ospfv3 [process-id] address-family ipv4 unicast

error_909Option: A
Sep 19, 2021

The given answer is correct

myrmikeOption: B
Dec 1, 2021

spapi0390 is right on. Looking at the config of the interfaces only ospfv3 ipv4 is enabled on the interfaces. The presumption being that the neighbor router is configured for ospfve ipv4 and not ipv6

NetworkingguyOption: B
Jan 31, 2022

B is the correct answer here

Reikidude00Option: B
Jul 19, 2022

B is correct here, af configuration must be done under router-config R1#show running-config | section router router ospfv3 4 router-id 1.1.1.1 ! address-family ipv4 unicast exit-address-family

bk989
Mar 28, 2024

also to add to this: We need the ospf adjacency to form to exchange routing info, whether the info is ipv4 or ipv6. In this case adjacency is failing because of ipv4 issue.

Ll123123Option: B
Oct 31, 2023

i choose B because OSPFv3 configuration require the ipv4 and ipv6 address family configuration under the ospfv3 process.

SeMo0o0o0Option: B
Jul 16, 2024

B is correct