Route-Optimized NAT Traversal Approach for LISP Mobile Node

The Locator/ID Separation Protocol (LISP) is being standardized in IETF, which separates the IP address functionality into routing locators (RLOCs) and endpoint identifiers (EIDs). A mobility support approach, LISP Mobile Node (LISP-MN), has been proposed to enable mobile node roaming. However, an issue that we are going to tackle in this paper remains. A LISP mobile node (MN) cannot communicate with other MNs or end hosts in a LISP site when it is behind a network address translation (NAT) device and can only acquire a private RLOC address. Although an extension for LISP-MN has introduced the NAT Traversal Router (NTR) as a proxy between MNs and the outside Internet, all traffic destined for MNs needs to go through the NTR device, which causes additional delays between end hosts and becomes a centralized performance bottleneck as the number of MNs increases. In this paper, we present the Route-Optimized NAT Traversal Approach for LISP Mobile Node (ROTAM). ROTAM makes slight changes to MNs and Map Server/Map Resolvers (MS/MR). It enables MNs to receive LISP data packet by opening a port in advance at the NAT device using Map-Register message. Using ROTAM reduces delays of the LISP data path and avoids the formation of a centralized bottleneck because there is no must-go-through point (e.g. NTR) in LISP data path.