350-401 Question #179: Real Exam Question with Answer & Explanation

Question

Which two LISP infrastructure elements are needed to support LISP to non-LISP internetworking? (Choose two)

Options

• APETR
• BPITR
• CMR
• DMS
• EALT

Explanation

To enable communication between LISP and non-LISP networks, Proxy Egress Tunnel Routers (PETR) are needed for traffic originating from LISP, while Map Resolvers (MR) facilitate the necessary EID-to-RLOC mapping lookups.

Common mistakes.

• B. A Proxy Ingress Tunnel Router (PITR) is used when a non-LISP site initiates communication to a LISP site; it receives traffic from a non-LISP network, encapsulates it, and sends it into the LISP domain.
• D. A Map Server (MS) stores EID-to-RLOC mappings for LISP sites and responds to Map-Requests; while crucial for LISP operation, it doesn't directly handle the internetworking encapsulation/decapsulation for LISP to non-LISP traffic like a PETR.
• E. ALT (Alternative Logical Topology) is a routing protocol used by Map Servers and Map Resolvers to find each other and exchange mapping information, but it is an internal LISP mechanism rather than an infrastructure element directly responsible for LISP to non-LISP internetworking.

Concept tested. LISP to non-LISP internetworking components

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_lisp/configuration/xe-3s/irl-xe-3s-book/irl-lisp-non-lisp.html

No community discussion yet for this question.