Huawei Exam H31-161 Topic 6 Question 84 Discussion

Actual exam question for Huawei's H31-161 exam

Question #: 84
Topic #: 6

Refer to the exhibit.

As shown in the figure, CE 1 and CE 3 belong to VPN A, CE 2 and CE 4

belong to VPN B, and users on different VPNs are not allowed to access each other. Which of the following configurations can enable mutual access between CE 1 and CE 4 but forbid cross-VPN access between other CEs?

Configuration of PE 1:

sysname PE 1

ip vpn-instance vpna

route-distinguisher 100:1vpn-target 1:1 3:3 export-extcommunity

vpn-target 1:1 3:3 import-extcommunity

# i

p vpn-instance vpnb

route-distinguisher 100:2

vpn-target 2:2 4:4 export-extcommunity

vpn-target 2:2 4:4 import-extcommunity

Configuration of PE 2:

sysname PE 2

ip vpn-instance vpna

route-distinguisher 200:1

vpn-target 1:1 export-extcommunity

vpn-target 1:1 import-extcommunity

ip vpn-instance vpnb

route-distinguisher 200:2

vpn-target 2:2 4:4 export-extcommunity

vpn-target 2:2 4:4 import-extcommunity

ARun vpn-target 1:1 on VPN b of PE 2
The configuration is as follows:
[PE 2]ip vpn vpnb
[PE 2-vpn-instance-vpnb]vpn-target 1:1 export-extcommunity
[PE 2-vpn-instance-vpnb]vpn-target 1:1 import-extcommunity

BRun vpn-target 2:2 on VPN a of PE 1The configuration is as follows:
[PE 1]ip vpn vpna
[PE 1-vpn-instance-vpna]vpn-target 2:2 export-extcommunity
[PE 1-vpn-instance-vpna]vpn-target 2:2 import-extcommunity

CRun vpn-target 3:3 on VPN b of PE 2
The configuration is as follows:
[PE 2]ip vpn vpnb
[PE 2-vpn-instance-vpnb]vpn-target 3:3 export-extcommunity
[PE 2-vpn-instance-vpnb]vpn-target 3:3 import-extcommunity
'

DRun vpn-target 4:4 on VPN a of PE 1
The configuration is as follows:
[PE 1]ip vpn vpna
[PE 1-vpn-instance-vpna]vpn-target 4:4 export-extcommunity
[PE 1-vpn-instance-vpna]vpn-target 4:4 import-extcommunity

Show Suggested Answer

Suggested Answer: C

by Sheron at Apr 14, 2024, 10:55 PM

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Viola

1 years ago

But the static route leading to CE 3 is learned based on the IBGP neighbor relationship between PEs.

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Freeman

1 years ago

I disagree. I believe the answer is B, as there are two possible routes that can reach CE 3.

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Joana

1 years ago

I agree with because the static route is imported to the OSPF and then to the VPN instance of the BGP.

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Viola

1 years ago

I think the correct answer is A.

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Rebecka

1 years ago

But if the routes are imported to BGP and OSPF, wouldn't that allow more routes to reach CE 3?

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Nicolette

1 years ago

I'm leaning towards C, I don't think any route can reach CE 3

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Eloisa

1 years ago

I disagree, I believe the answer is A because of the way routes are imported and filtered

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Rebecka

1 years ago

I think the answer is B because there are two routes that can reach CE 3

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Frank

1 years ago

Haha, I bet the exam writers are trying to trip us up with this one. They probably want us to think about things like OSPF loopback detection and how that might impact the routing on PE1-B.

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Blair

1 years ago

Aha, I think I see where this is going. The static route on PE1-A is likely being imported into the OSPF domain, and then the OSPF route is being imported into the VPN instance of the BGP. That would give us two possible routes to CE3 on PE1-B.

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Arlette

1 years ago

I agree. One route from IBGP neighbor and the other from OSPF category-5 route.

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Daren

1 years ago

I think the answer is B) Two

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Alpha

1 years ago

Okay, let's break this down step-by-step. We have OSPF being used to exchange VPN route information between CE1 and PE1-A, and between CE2 and PE1-B. Then we have a static route configured on PE1-A leading to CE3.

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Wilda

1 years ago

Hmm, I think the key here is understanding how the OSPF and BGP routes are being imported and exchanged between the different components. That will likely determine the number of routes that PE1-B can reach CE 3 with.

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Lilli

1 years ago

Yeah, this is definitely not a straightforward question. We need to carefully consider the different routing mechanisms and how they interact in this scenario.

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Janine

1 years ago

This is a tricky question. It seems to involve some complex networking concepts like dual-plane bearer networks, OSPF, BGP, and VPN routing. I'm not sure I fully understand all the details, but I'll give it my best shot.

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