4-4 - Summary Challenge

Question 1

Match the inter-AS option with the correct description:

Descriptions:
An IGP or BGP exchanges customer routing information between ASBRs.

This method provides more scalability than the back-to-back VRF method.

This method is highly scalable, because there is no route overhead on ASBRs.

The IETF has defined these networks in RFC 4364 section 10 “Multi-AS Backbones.”

Options:
single-hop MP-EBGP
combination of A and B
back-to-back VRF
multihop MP-EBGP

Answer 1

An IGP or BGP exchanges customer routing information between ASBRs. == back-to-back VRF

This method provides more scalability than the back-to-back VRF method. == single-hop MP-EBGP

This method is highly scalable, because there is no route overhead on ASBRs. == multihop MP-EBGP

The IETF has defined these networks in RFC 4364 section 10 “Multi-AS Backbones.” == combination of A and B

Question 2

What is true about the option D inter-AS?

A. ASBR peers subinterfaces are not enabled to receive MPLS traffic.
B. Traffic that flows between ASBRs is not labeled.
C. It combines the best functionality of an inter-AS Option A and Option B.
D. You can apply QoS mechanisms to isolate VRF traffic.

Answer 2

C

Question 3

What is true about the CSC MPLS VPN services?

A. One CSC backbone cannot provide services to both VPN service providers and ISP.
B. The customer service providers operate their own long-distance network.
C. You can use special link types only inside the CSC backbone.
D. You can use one CSC backbone to connect many POP sites.

Answer 3

D

Question 4

What is true about the CSC architecture?

A. For LDP and IGP, you must disable MPLS on the link between the customer and the backbone.
B. For MP-EBGP, you must enable LDP on links between the customer and the backbone.
C. You use MPLS between backbone PE routers and customer carrier VPN sites.
D. You use MPLS between backbone PE routers and customer carrier VPN sites.

Answer 4

C

Question 5

What is true about using MP-EBGP instead of LDP to exchange labels?

A. Service providers who prefer BGP choose this method.
B. You can use MP-EBGP to exchange the labels of CSC-CE loopback addresses.
C. An MP-IBGP session between the CE routers provides VPNv4 routing.
D. You cannot deploy route reflectors to resolve full-mesh requirements.

Answer 5

A

Question 6

What is true about the CSC data flow when you use IGP and LDP?

A. When the packet enters the backbone carrier network, the LDP label is not swapped.
B. The VPN label identifies packets from different VPNs.
C. A label stack transports customer packets through carrier networks.
D. The label stack consists of three labels in the customer carrier network and two labels in the backbone carrier network.

Answer 6

C

Question 7

What is true about the CSC data flow when you use MP-EBGP?

A. The label stack consists of three labels in the customer carrier network and two labels in the backbone carrier network.
B. The outer label is a VPN label that identifies packets from the same VPN.
C. The inner label is a VPN label that identifies packets from the same VPN.
D. Due to penultimate hop popping, the packet arrives at the destination with two labels.

Answer 7

C