Chapter 16. Testing HIP Rendezvous and HIP Relay Server/Mechanisms

Table of Contents

About the HIP Rendezvous and HIP Relay Mechanisms
The RVS and HIP Relay Configuration File
About the RVS and HIP Relay Configuration File
Configuration File Setup
HIP Rendezvous Mechanisms
Preliminary Setup
HIP Connection Test Using the Rendezvous Server
HIP Relay Mechanisms
Preliminary Setup
HIP Connection Test Using the Relay Server
Additional RVS and HIP Relay Features
Issues in RFC 5203
HIPL Solutions to the Issues in RFC 5203
Additional hipconf commands

Abstract

In this chapter, we guide how to test the Host Identity Protocol rendezvous and relay mechanisms.

About the HIP Rendezvous and HIP Relay Mechanisms

The rendezvous and relay extensions extend HIP and the HIP registration extension for initiating communication between HIP nodes via a HIP rendezvous server or a HIP relay server. The rendezvous server (RVS) and the HIP relay server serve as an initial contact point ("rendezvous point") for its clients. The clients of an RVS / HIP relay server are HIP nodes that use the HIP Registration Protocol to register their HIT to IP address mappings with the server. After this registration, other HIP nodes can initiate a base exchange using the IP address of the server instead of the current IP address of the node they attempt to contact. Essentially, the clients of a server become reachable at the server's IP addresses.

The primary objective of the rendezvous extension is to improve reachability and operation when HIP hosts are mobile or multi-homed. In addition, the rendezvous extension is necessary when a middlebox separates the responder from the public realm. In a Network Address Translator (NAT), session establishment is uni-directional from private address realm to public address realm. Therefore, if a host has detected that it is behind a NAT, the host must first register with the RVS when it is going to act as a responder of a base exchange. The rendezvous extension allows HIP initiators to reach the responder when the NAT devices involved all perform address independent mapping. Such NATs are commonly referred to as "good" NATs.

The primary objective of the HIP relay extension, on the other hand, is to improve reachability when HIP hosts are separated from each other by a NAT device that performs address dependent mapping. Such NATs are commonly referred to as "bad" NATs. In practice, the HIP relay servers are used to relay the Interactive Connectivity Establishment (ICE) address candidates that are encapsulated in HIP messages.

The main difference between the rendezvous server and the HIP relay server is that the RVS only relays I1 packet of the base exchange while the HIP relay server relays all HIP packets. We can summarize the use cases of the RVS and the HIP relay as follows.

The rendezvous server should be used when:

  • The responder is mobile or multi-homed.

  • A NAT device that performs endpoint independent mapping separates the responder from the public Internet.

The HIP relay server should be used when:

  • A NAT device that performs endpoint dependent mapping is en route between the initiator and the responder. Note that it does not make a difference whether the NAT device is at initiator's side or at responder's side. A single "bad" NAT en route is enough to make the communication impossible between the initiator and the responder unless a HIP relay is used.

17th of July 2008