Cisco Enterprise Network Core Technologies (ENCOR) Practice Exam

The Egress Tunnel Router (ETR) plays a crucial role in the Locator/ID Separation Protocol (LISP) architecture, primarily by connecting a site to the LISP-capable network. Its main function is to serve as a point where traffic exits the LISP domain, managing data packets that are being sent out to external networks. The ETR receives packets from internal hosts, encapsulates them if necessary, and forwards them to their destination according to the Locator/ID mapping provided by the xTR (which includes both ETR and Ingress Tunnel Router - ITR).

This functionality is essential for integrating local networks into larger LISP environments, enabling effective communication across diverse network segments. Therefore, the identification of the ETR as a connection point to the LISP network is key to understanding its purpose.

In contrast, the other choices describe functions that are either not specific to the role of the ETR or are more aligned with the responsibilities of other components in a LISP architecture. For instance, initiating traffic flows for all protocols is a broader task that involves many devices, while storing EID-to-RLOC mappings is typically managed by a mapping database service rather than the ETR itself. Furthermore, routing functions within a site are handled by