7.9. STUDY QUESTIONS

  1. In which cases would a customer prefer an overlay VPN model over a peer VPN model?

  2. In the MPLS/VPN model, a single BGP session carries the routes from all VPNs between two PEs. If the approach of creating separate BGP instances across the core had been taken, what would have been the number of sessions required to support 1000 VPNs, each with 100 sites (assume no route reflectors are used, and 100 PEs)?

  3. At first glance, it would seem that an RD allocated with per-VPN granularity would be sufficient to identify the VPN. What would be the limitations of such an approach?

  4. Describe the RT and RD allocation of two VPN customers, A and B, that wish to provide an overlapping VPN as follows. All customers of VPNA are allowed to access the server whose address is 10.1.1.1 at site 1 of VPNA. Customers in site 1 of VPNB are also allowed to access this server, but no other customers of VPN B are allowed to access it.

  5. To resolve a VPN route, a tunnel capable of transporting MPLS traffic is required to the BGP next-hop. What happens when this tunnel goes away?

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