350-401 Question #1229: Real Exam Question with Answer & Explanation

The correct answer is B: ETR. In a LISP architecture, the Egress Tunnel Router (ETR) is responsible for receiving encapsulated LISP traffic and forwarding the original IP packets to the intended endpoints within its local site.

Submitted by tom_us· Mar 6, 2026DOMAIN_LIST_NOT_PROVIDED

Question

Which device, in a LISP routing architecture, receives and de-encapsulates LISP traffic for endpoints within a LISP-capable site?

Options

AMR
BETR
CMS
DITR

Explanation

In a LISP architecture, the Egress Tunnel Router (ETR) is responsible for receiving encapsulated LISP traffic and forwarding the original IP packets to the intended endpoints within its local site.

Common mistakes.

A. An MR (Map Resolver) is responsible for receiving LISP map-requests from an ITR and forwarding them to the appropriate Map Server (MS).
C. An MS (Map Server) receives map-register messages from ETRs, stores the EID-to-RLOC mappings, and responds to map-requests forwarded by Map Resolvers.
D. An ITR (Ingress Tunnel Router) is responsible for receiving IP packets from non-LISP hosts or sites and encapsulating them with a LISP header before forwarding them towards the destination ETR.

Concept tested. LISP routing architecture roles

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_lisp/configuration/xe-16/irl-xe-16-book/irl-overview.html

Topics

#LISP#Routing architecture#ETR

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