300-320 · Question #258
A designer should have which three technologies in the network before configuring MPLS Layer 3 VPNs? (Choose three.)
The correct answer is A. MPLS B. LDP C. Cisco Express Forwarding. MPLS Layer 3 VPNs have three fundamental prerequisites on Cisco devices: (1) MPLS - the core label-switching infrastructure that forwards packets based on labels rather than IP lookups; (2) LDP (Label Distribution Protocol) - the protocol that distributes and negotiates label…
Question
A designer should have which three technologies in the network before configuring MPLS Layer 3 VPNs? (Choose three.)
Options
- AMPLS
- BLDP
- CCisco Express Forwarding
- DVSS
- EvPC
- FVRRP
How the community answered
(36 responses)- A89% (32)
- D3% (1)
- E6% (2)
- F3% (1)
Explanation
MPLS Layer 3 VPNs have three fundamental prerequisites on Cisco devices: (1) MPLS - the core label-switching infrastructure that forwards packets based on labels rather than IP lookups; (2) LDP (Label Distribution Protocol) - the protocol that distributes and negotiates label bindings between MPLS-enabled routers so each router knows which label to use for each prefix; (3) Cisco Express Forwarding (CEF) - required on Cisco routers because MPLS depends on CEF for the FIB (Forwarding Information Base) and label imposition/disposition. Without CEF, MPLS cannot function on Cisco platforms. Options D (VSS - Virtual Switching System), E (vPC - virtual Port Channel), and F (VRRP - Virtual Router Redundancy Protocol) are all high-availability or chassis-virtualization technologies that have no dependency relationship with MPLS L3 VPN configuration.
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