Exam 350-401 topic 1 question 411 discussion

ANS RLOC, RESOLVER, ITR Map resolver (MR): This is a network device (typically a router) that receives LISP-encapsulated map requests from an ITR and finds the appropriate ETR to answer those requests by consulting the map server.

Steps: 1. ITR sends an encapsulated Map-Request to the MR. 2. MR decapsulates the Map-Request and forwards it to the MS. 3. MS responds with a Map-Reply containing RLOCs. 4. MR forwards the Map-Reply to the ITR. 5. ITR encapsulates the original data packet using the RLOCs and sends it to the ETR. 6. ETR decapsulates the packet and forwards it to the destination endpoint. This process ensures that packets can be routed efficiently through the LISP network by resolving endpoint identifiers to routing locators and encapsulating packets accordingly.

RLOC MAP Resolver ITR

To my mind: - RLOC - MR - ITR This is from Cisco's 31 days before CCNP book: "Map resolver (MR): It accepts encapsulated Map-Request messages sent by ITRs, decapsulates them, and then forwards them over the ALT router toward the ETRs responsible for the EIDs being requested." So, MS creates the database (based on ETR registerations) that the MR is using.

Roof, map resolvers, itr

D. The function of the LISP MR is to accept encapsulated Map-Request messages from ingress tunnel routers (ITRs), decapsulate those messages, and then forward the messages to the MS responsible for the egress tunnel routers (ETRs) that are authoritative for the requested EIDs.

I agree with RLOC and Resolver what i dont understand is why the 3rd option is ITR. This is not making sense to me.

ANS RLOC, RESOLVER, ITR routing locator (RLOC) An IPv4 or IPv6 address of an ETR that is Internet facing or network core facing map resolver (MR) A network device (typically a router) that receives LISP-encapsulated map requests from an ITR and finds the appropriate ETR to answer those requests by consulting the map server. If requested by the ETR, the MS can reply on behalf of the ETR. ingress tunnel router (ITR) A router that LISP-encapsulates IP packets coming from EIDs that are destined outside the LISP site.

The statement is mixed up!? "receives map request messages from ITR" ---> MR "searches the appropriate ETR by consulting mapping database" ---> MS So basically what they are describing is a MS/MR device...

The map resolver (MR), on the other hand, accepts LISP encapsulated map requests from an ITR. Based on a map request, two things may happen. If the destination IP address is part of the EID namespace, the MR finds the appropriate EID-to-RLOC mapping by consulting the distributed mapping database system. https://www.ciscopress.com/articles/article.asp?p=2992605

Given answer is correct! When MS and MR function runs on separate devices: 1. ITR --'map-request'--> MAP-Resolver (MR) 2. MR --- forwards 'map-request' -----> MAP-Server (MS) 3. MS --- check DB for RLOC -- finds (ETR) 4. MS -- Sends 'map-request' to ------> Egress Tunnel Router (ETR) 5. ETR -- sends 'MAP-Reply' directly to ----->ITR When MS and MR function runs on same devices (which is this question): 1. ITR --'map-request'--> MAP-Resolver (MR/MS) 2. MS --- check DB for RLOC -- find (ETR) 3. MS -- Sends 'map-request' to ------> Egress Tunnel Router (ETR) 4. ETR -- sends 'MAP-Reply' directly to ----->ITR

RLOC, RESOLVER, ITR for sure. Link provided by PALURDIN.

Ans: RLOC, Resolver, ITR.

I guess it is map resolver instead of map server: 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-92481C7B-F44D-4D8C-8085-A2E98530CA50:~:text=and%20ITR%20components).-,LISP%20Map%20Resolver,-Like%20an%20MS