JNCIS-SP Exam: Provisioning Layer 3 VPNs

Preparing Provider Core for VPN Traffic

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Question

You have been asked to provision a service provider's network to accommodate Layer 3 VPNs as defined in RPC 4364.

Which three tasks must be performed before the provider core is ready to carry VPN traffic? (Choose three.)

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Explanations

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A. B. C. D. E.

BCE

To provision a service provider's network to accommodate Layer 3 VPNs as defined in RFC 4364, the following three tasks must be performed before the provider core is ready to carry VPN traffic:

A. All P routers and PE routers must be configured to support MPLS administrative-groups (colors): MPLS administrative-groups, also known as colors, are used to segregate and differentiate VPN traffic. Configuring MPLS administrative-groups on all P routers and PE routers is necessary to ensure that VPN traffic is properly segregated and routed through the network. This is a critical step in implementing Layer 3 VPNs and should be completed before any VPN traffic is carried across the network.

B. All PE routers must be configured to support Multiprotocol BGP (MP-BGP): Multiprotocol BGP (MP-BGP) is used to distribute VPN routing information between PE routers in a Layer 3 VPN. All PE routers must be configured to support MP-BGP to ensure that they can exchange VPN routing information with each other. This is necessary for proper VPN routing and forwarding, and must be completed before any VPN traffic is carried across the network.

C. All P routers and PE routers must have a signaling protocol such as RSVP or LDP enabled: A signaling protocol is required to set up label-switched paths (LSPs) between routers in an MPLS network. RSVP (Resource Reservation Protocol) and LDP (Label Distribution Protocol) are two commonly used signaling protocols. These protocols must be enabled on all P routers and PE routers to ensure that LSPs can be established between them. This is necessary for the proper functioning of MPLS and Layer 3 VPNs, and should be completed before any VPN traffic is carried across the network.

The following tasks are not required for provisioning a service provider's network to accommodate Layer 3 VPNs as defined in RFC 4364:

D. All P routers and PE routers must have a discovery protocol such as LLDP or CDP enabled: Discovery protocols such as LLDP (Link Layer Discovery Protocol) and CDP (Cisco Discovery Protocol) are used to discover information about neighboring devices on a network. While these protocols may be useful for network management and troubleshooting, they are not required for the proper functioning of MPLS or Layer 3 VPNs.

E. All P routers and PE routers must have MPLS reachability to PE routers: MPLS reachability to PE routers is important for ensuring that MPLS labels can be exchanged between routers. However, this is not a required step for provisioning a service provider's network to accommodate Layer 3 VPNs as defined in RFC 4364. MPLS reachability can be established after the other tasks have been completed.