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Juniper Exam JN0-664 Topic 1 Question 44 Discussion

Actual exam question for Juniper's JN0-664 exam
Question #: 44
Topic #: 1
[All JN0-664 Questions]

Refer to the exhibit.

Click the Exhibit hutton.

You are configuring an interprovider Option C Layer 3 VPN to connect two customer sites.

Referring to the exhibit, which three statements are correct? (Choose three.)

Show Suggested Answer Hide Answer
Suggested Answer: A, B, C

Interprovider Option C for Layer 3 VPNs involves the use of Autonomous System Boundary Routers (ASBRs) to exchange labeled VPN-IPv4 routes between different Autonomous Systems (AS). This option requires BGP sessions between ASBRs, and the VPN routes are carried end-to-end using MPLS labels. Here's a detailed analysis of the roles of different routers in this scenario:

1. **ASBR Routers**:

- ASBRs are responsible for exchanging VPN-IPv4 routes between different ASes.

- **A. ASBR routers maintain the internal routes from its own AS and the loopback addresses from the other AS PEs.**

- Correct. ASBRs maintain routes to internal destinations within their own AS, and they also need to know the loopback addresses of PEs in the other AS to set up the BGP sessions and MPLS tunnels.

2. **PE Routers**:

- PE routers are responsible for maintaining VPN routes and label information to forward VPN traffic correctly.

- **B. PE routers maintain the internal routes from its own AS, the loopback address from the other AS PEs, and the L3VPN routes.**

- Correct. PE routers need to maintain:

- Internal routes within their AS for routing.

- Loopback addresses of other AS PEs for establishing MPLS LSPs.

- L3VPN routes to provide end-to-end VPN connectivity.

3. **P Routers**:

- P routers are the core routers that do not participate in BGP VPN routing but forward labeled packets based on MPLS labels.

- **C. P routers only maintain the internal routes from their own AS.**

- Correct. P routers maintain the internal routing information to forward packets within the AS and use MPLS labels for forwarding VPN packets. They do not maintain VPN routes or routes from other ASes.

4. **Incorrect Statements**:

- **D. P routers maintain the internal routes from its own AS and the loopback address from the other AS PEs.**

- Incorrect. P routers do not need to maintain the loopback addresses of other AS PEs. They only maintain internal routing and MPLS label information.

- **E. ASBR routers maintain the internal routes from its own AS, the loopback address from the other AS PEs, and the L3VPN routes.**

- Incorrect. ASBR routers do not maintain L3VPN routes. They exchange labeled VPN-IPv4 routes with other ASBRs and forward them to PE routers.

**Conclusion**:

The correct answers are:

**A. ASBR routers maintain the internal routes from its own AS and the loopback addresses from the other AS PEs.**

**B. PE routers maintain the internal routes from its own AS, the loopback address from the other AS PEs, and the L3VPN routes.**

**C. P routers only maintain the internal routes from their own AS.**

**Reference**:

- Juniper Networks Documentation on Interprovider VPNs: [Interprovider VPN Configuration](https://www.juniper.net/documentation/en_US/junos/topics/topic-map/mpls-vpn-interprovider.html)

- MPLS and VPN Architectures, CCIP Edition by Ivan Pepelnjak and Jim Guichard


Contribute your Thoughts:

Gilma
16 days ago
I guess the P routers are just too proud to learn about the other AS, huh?
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Shayne
25 days ago
I'm not sure about statement E, I think it might be C instead.
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Daron
1 months ago
I agree with Devora, those statements make sense based on the exhibit.
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Gilbert
1 months ago
C is definitely wrong. The P routers can't just maintain the internal routes from their own AS, they need to know about the other AS as well to enable the inter-provider connectivity.
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Jesusita
1 months ago
A and E both seem plausible. The ASBR routers should have the routes from their own AS, the loopback addresses of the other AS PEs, and potentially the L3VPN routes as well.
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Vince
17 days ago
Yes, B is correct. PE routers maintain internal routes from their own AS, loopback addresses from other AS PEs, and L3VPN routes.
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Giuseppe
19 days ago
So, that means B is also correct since PE routers maintain those routes as well.
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Chau
20 days ago
I agree, ASBR routers maintain internal routes from their own AS, loopback addresses from other AS PEs, and L3VPN routes.
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Nada
21 days ago
I think A and E are correct. ASBR routers should have routes from their own AS and loopback addresses from other AS PEs.
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Ettie
1 months ago
D looks correct to me. The P routers should have the internal routes from their own AS and the loopback addresses from the other AS PEs to forward the traffic between the customer sites.
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Denae
4 days ago
In addition to that, the ASBR routers also play a role in maintaining internal routes, loopback addresses, and L3VPN routes for the interprovider Option C Layer 3 VPN.
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Matthew
6 days ago
Yes, the P routers need to maintain the internal routes from their own AS and the loopback addresses from the other AS PEs for proper communication.
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Leonie
9 days ago
I think D is correct too. The P routers play a crucial role in forwarding traffic between the customer sites.
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Delsie
2 months ago
I think B is the correct answer. The PE routers need to maintain the internal routes, the loopback addresses of the other AS PEs, and the L3VPN routes to enable the inter-provider connectivity.
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Charlette
25 days ago
Yes, B is one of the correct answers. ASBR routers also play a role in maintaining certain routes for the interprovider Option C Layer 3 VPN.
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Nada
28 days ago
I agree with you, B is the correct answer. PE routers need to maintain those routes for inter-provider connectivity.
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Devora
2 months ago
I think the correct statements are A, B, and E.
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