Which tool identifies the point of failure in a P2MP LSP from the ingress LSR?

Question

Options

• AJitter TLV
• BSPAN
• CP2MP traceroute
• DP2MP ping

• A
  6% (3)
• B
  2% (1)
• C
  90% (43)
• D
  2% (1)

Explanation

P2MP traceroute is specifically designed to trace the path of a Point-to-Multipoint Label Switched Path hop-by-hop from the ingress LSR, using MPLS echo request packets that reveal exactly where the forwarding breaks down across the multipoint tree. P2MP ping (D) only confirms whether end-to-end connectivity exists or not - it tells you that something is broken but not where, making it useful for detection but not localization. Jitter TLV (A) is a Type-Length-Value field used in OAM packets to measure delay variation, which is a performance metric unrelated to failure localization. SPAN (B) is a port mirroring feature on switches used to copy traffic for analysis, and has no role in MPLS LSP diagnostics.

Memory tip: Think of it this way - ping = "is it alive?" (yes/no), traceroute = "where did it die?" (hop-by-hop). The same logic applies to their P2MP counterparts; when you need to locate the failure point, always reach for the traceroute variant.

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