CCIE SP MPLS FAQ: MPLS/VPN Architecture Overview

CCIE SP MPLS FAQ: MPLS/VPN Architecture Overview

ccie-sp-mpls-faq-mpls-vpn-architecture-overview

Figure: Virtual Routers Created in a PE Router

Q1. How can overlapping IP addresses be supported between customer sites when MPLS VPN is deployed?

Answer: Each VPN has access to its own routing and forwarding tables

Q2. What routing information is contained within the global routing table on PE routers?

Answer: Routes internal to the P network (internal service provider

Q3. The combination of the per-VPN routing table and per-VPN forwarding table is known as what?

Answer: Virtual Routing and Forwarding Instance (VRF).

Q4. What is a route target?

Answer: A route target is a 64 bit value attached to a BGP route as an

Q5. What is the purpose of the route target?

Answer: To determine which routes must be imported into which VRFs so that VPN membership can be achieved.

Q6. How are client VPN routes distributed across the service provider P network?

Answer: Through use of Multiprotocol BGP (MP-BGP), which provides extensions to BGP so that non-IP prefixes can be transported.

Q7. What is a route distinguisher (RD)?

Answer: The RD is a 64-bit prefix prepended to a VPN client IPv4 address to make it globally unique across the P network.

Q8. What is a routing context?

Answer: It is a routing instance within a routing process that distinguishes between different VPN routing information.

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