An Egress Tunnel Router (ETR) connects a site to the LISP-capable part of a core network (such as the Internet), publishes EID-to-RLOC mappings for the site, responds to Map-Request messages, and decapsulates and delivers LISP-encapsulated user data to end systems at the site. Reference: 3s/irl-xe-3s-book/irl-overview.html