| 1 |
In which type of MPLS Layer 3 VPN architecture does the backbone service provider offer an MPLS VPN service to customer service providers? |
| Answer: |
This type of architecture is known as carriers' carrier (CSC). |
| 2 |
How are internal routes are advertised between CSC customer sites via the carriers' carrier backbone network? |
| Answer: |
Internal routes are advertised using any of the regular PE-CE routing protocols. |
| 3 |
How are label bindings advertised between CSC PE and CE routers? |
| Answer: |
Label bindings are advertised using either LDP or BGP. |
| 4 |
How are external routes advertised in a CSC architecture? |
| Answer: |
External routes are advertised directly between customer sites using BGP. |
| 5 |
What type of MPLS Layer 3 VPN network architecture is required if a customer VPN has some of its sites connected to one autonomous system but other sites connected to other autonomous systems? |
| Answer: |
An inter-autonomous system MPLS VPN architecture is required in this case. |
| 6 |
What are the three methods of provisioning an inter-autonomous system MPLS VPN architecture? |
| Answer: |
Using VRF-to-VRF connectivity at ASBRs; using the advertisement of labeled VPN-IPv4 (VPNv4) between ASBRs with MP-eBGP; and using the advertisement of labeled VPN-IPv4 (VPNv4) between route reflectors in different autonomous systems with multihop MP-eBGP. |
| 7 |
Describe the label stack that is prepended to packets as they cross inter-autonomous system links in an inter-autonomous system MPLS VPN architecture when using VRF-to-VRF connectivity at ASBRs. |
| Answer: |
Packets are unlabeled in this case. The peer ASBRs regard each the other as a CE routers. |
| 8 |
What is the effect of the no bgp default route-target filter command? |
| Answer: |
Usually, when a router receives VPN-IPv4 routes with route targets that do not match the import route targets configured within any of its VRFs, the router drops them. The no bgp default route-target filter command ensures that VPN-IPv4 routes are not dropped in this case. |
| 9 |
What are the two common methods of supporting IP multicast transport between customer sites in an MPLS Layer 3 VPNs? |
| Answer: |
The two methods are point-to-point GRE tunnels and MVPNs. |
| 10 |
What are the main advantages of using MVPN when compared to point-to-point GRE tunnels? |
| Answer: |
MVPN is much more scalable than a mesh of point-to-point GRE tunnels; MVPN does not require special configuration within the customer network. |