Exam 350-401 topic 1 question 95 discussion

Sorry I forgot the post the article and here it is “ To establish communication between LISP and non LISP sites an extra components must be use, a proxy ingress tunnel router (PITR), which allows non-LISP sits to send packet toward LISP sites. The PITR attracts traffic from non-LISP sites by advertising aggregate prefixes for the LISP EID into the non-LISP network. When PITR receives packets from non-LISP sites it encapsulate and forward these packets to LISP sites. The second element to establish communication between the LISP and non-LISP sites is called a proxy egress tunnel router (PETR). The PETR allows the communication from the LISP sites to the non-LISP sites. The PETR receives LISP encapsulated traffic from ITR. The PITR and PETR can be combine and deployed on the same node called (PxTR) to provide symmetric traffic when stateful inspection devices are deployed between LISP and non-LISP sites.”

Given answer is correct

Correct Answer C The Proxy ITR (P-ITR) is the correct answer because it enables a non-LISP site to send traffic to a LISP site, which is the foundational step for communication between the two. The Proxy ETR (P-ETR), while important for LISP-to-non-LISP traffic, isn’t the primary component for enabling the initial communication from a non-LISP site, which is implied by the question’s focus. Cisco’s documentation supports this prioritization of the P-ITR for non-LISP-to-LISP integration.

D is correct

Proxy ETR (PETR): A PETR is a LISP Infrastructure device that allows EIDs at LISP sites to successfully communicate with devices located at non-LISP sites

D is correct

Ingress Tunnel Router (ITR) – LISP-encapsulates IP packets from EIDs forwarded outside the LISP site. Egress Tunnel Router (ETR) – de-encapsulates LISP-encapsulated IP packets from non-LISP sites destined for EIDs in the LISP site. Tunnel Router (xTR) – can execute both ITR and ETR functionalities. Proxy Ingress Tunnel Router (PITR) – functions similarly to ITR but for non-LISP sites that send traffic to EIDs. Proxy Egress Tunnel Router (PETR) – functions similarly to ETR but for EIDs that send traffic to non-LISP destinations. Proxy xTR (PxTR) – can execute both PETR and PITR functionalities. LISP Router – A router that functions as ITR, ETR, PITR, and/or PETR. Map Server (MS) – learns EID-to-prefix mapping entries from the ETR and stores the entries in an EID-to-RLOC mapping database. Map Resolver (MR) – receives LISP-encapsulated map requests from the ITR and checks the Map Server (MS) to locate the proper ETR response to the requests. Map Server/Map Resolver (MS/MR) – a device with integrated MS and MR functionalities.

I see your point but the questions states "what is required for a LISP site" so shouldn't the focus be on what the LISP site needs ? A LISP site needs an ITR to communicate with ETRs and PETRs.

Proxy ITR (PITR): PITRs are just like ITRs but for non-LISP sites that send traffic to EID destinations. Proxy ETR (PETR): PETRs act just like ETRs but for EIDs that send traffic to destinations at non-LISP sites. Source: CCNP and CCIE Enterprise Core: ENCOR 350-401 Official Cert Guide

LISP Proxy ETR A LISP PETR implements ETR functions on behalf of non-LISP sites. A PETR is typically used when a LISP site needs to send traffic to non-LISP sites but the LISP site is connected through an access network of a service provider that does not accept nonroutable EIDs as packet sources. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_lisp/configuration/xe-3s/irl-xe-3s-book/irl-overview.html#GUID-EBD6EA80-8C5E-448B-BE3B-4B712450CEC2

answer D is ok

answer D is ok!

D is correct

ETR, (Egress) from internal to External ITR, (Internal) from External to Internal

voting. provided answer is correct

D! LISP Proxy ETR ==> Receives traffic from LISP sites and sends it to non-LISP sites

As explaned by Nhan