Which LISP component is required for a LISP site to communicate with a non-LISP site?

Question

Options

• AETR
• BITR
• CProxy ETR
• DProxy ITR

• A
  7% (2)
• B
  4% (1)
• C
  89% (24)

Explanation

LISP Proxy ETR Explanation

A Proxy ETR (PETR) is required for a LISP site to communicate with a non-LISP site because it acts on behalf of LISP-capable sites when sending traffic to destinations that do not understand LISP encapsulation - it decapsulates the LISP-encapsulated packets and forwards them into the non-LISP internet. An ETR (Egress Tunnel Router) only decapsulates traffic destined within a LISP site, so it cannot bridge communication to non-LISP destinations (Option A). An ITR (Ingress Tunnel Router) encapsulates traffic leaving a LISP site but has no mechanism to resolve or reach non-LISP EIDs on its own (Option B). A Proxy ITR (PITR) serves the opposite role - it allows non-LISP sites to reach LISP sites by encapsulating traffic on their behalf, not the other way around (Option D).

Memory Tip: Think of the P in PETR as "Path out" - when a LISP site needs a path out to a non-LISP world, it uses a Proxy ETR. Conversely, a PITR provides a path in for non-LISP sites reaching LISP sites.

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