Which method can be used to discover targeted LDP neighbors dynamically when configuring VPLS between PE routers?

Question

Options

• ABGP autodiscovery
• BVPLS peers under the VFI
• CVPWS
• DBGP

• A
  92% (55)
• B
  5% (3)
• C
  2% (1)
• D
  2% (1)

Explanation

BGP autodiscovery allows PE routers in the same VPLS instance to find each other automatically using BGP NLRI (specifically the BGP VPLS address family), eliminating the need to manually enumerate every targeted LDP peer - once PEs discover each other via BGP, they signal pseudowires using LDP without static configuration.

Option B (VPLS peers under the VFI) is the static/manual alternative - you explicitly list each remote PE neighbor, which is the opposite of dynamic discovery. Option C (VPWS) is a point-to-point Layer 2 service, not multipoint VPLS, and has no role in PE neighbor discovery. Option D (BGP) is a distractor because it names the protocol without the key qualifier - plain BGP can also signal VPLS pseudowires (BGP-signaled VPLS), which would bypass LDP entirely rather than discovering LDP neighbors.

Memory tip: Think of it as two jobs - find the peers vs. signal the pseudowires. BGP autodiscovery handles the find step dynamically; LDP then handles the signal step. If the question mentions "dynamic + LDP," the answer is always BGP autodiscovery.

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