Subject: [mobile-ip] Unresolved issue #9: Terminology

From: Jari Arkko <[email-masked]>
Date: Thu, 11 Apr 2002 21:22:30 +0300

Background:

Some of the MIPv6 terminology was changed in draft 16:

   - Some options inside an IPv6 DO became messages inside the Mobility Header
   - One option (HAO) was left inside the IPv6 DO
   - All suboptions inside options became parameters inside messages

It isn't clear if these are the best terms. Also, draft 16 introduced
a number of new mechanisms and concepts, some of which need to be
talked about and referred to. These may need terms and abbreviations.
For instance, we have the Return Routability (RR) mechanism and
signaling exchange. RR itself encompasses a number of concepts, such
as nonces, cookies, and nonce indices. A new message, Binding Missing
was created, and the role of some existing messages has changed:
Binding Request can no longer be used without an existing binding. It
has been discussed that Binding Acknowledgement might also be used to
respond in error situations relating to other messages than Binding
Update. The role of the authentication fields has changed from draft
15.

Question: What are the correct terms for these things? Do we have all
necessary terms?

Proposal:

Message
=======

The Mobile IPv6 protocol defines a number of messages that used in
creating and managing bindings. The Mobility Header carries all
these messages.

Mobility Option (alt. Parameter)
================================

In order to allow optional fields that may not be needed in every use
of any given Mobility Header, and to allow future extensions to the
format of these messages to be defined, any of the Mobility Header
messages defined in this document MAY include one or more options.
Such options are included in the data portion of the message itself,
after the fixed portion of the message data.

Destination Option (alt. Option)
================================

Destination options are carried by the IPv6 Destination Options
extension header. Mobile IPv6 defines one new destination option,
the Home Address Destination Option. (Question: is this going to
be too confusing, having too different types of options in the same
specification?)

RR Procedure
============

The Return Routability Procedure consists of the Home Test Init, Home
Test, Care-of Test Init, and Care-of Test messages between the mobile
node and the correspondent node. The RR Procedure is used to establish
a suitable key for eventual BU authorization, based on cookies
received from the correspondent node in these messages.

Correspondent Binding Procedure (alt. BU Procedure)
===================================================

The Correspondent Binding Procedure (CBP) consists of the RR Procedure,
Binding Update message, and an optional Binding Acknowledgement message.

Nonce (alt. something else?)
============================

Nonces are random numbers used internally by the correspondent node in
the creation of cookies that will be later used for Binding Update
authorization. The nonces are not specific to a mobile node, and are
kept secret within the correspondent node, only used as one input in
the creation of the cookies. The correspondent node should try to keep
track of nonces up to MAX_COOKIE_LIFE seconds after their last use.

Nonce Index
===========

In the process of authorizing a Binding Update, the mobile node uses a
particular set of cookies, which in turn have been produced using a
particular set of nonces. For security reasons, neither the cookies or
the nonces can appear in the Binding Update message. Given that
multiple nonces may be in use simultaneously, the correspondent node
has to decide which nonce to use in verifying the authorization. This
decision can be made by sequentially trying all possible nonces, but
for performance reasons the Nonce Index can be used to find the right
nonce directly.

Cookie
======

Cookies are cryptographically produced entities that are used by mobile
nodes in the process of authorizing Binding Updates.

Binding Missing
===============

This is the Binding Missing message.

Binding Refresh Request (alt. Binding Request)
==============================================

This is the old Binding Request message.

Authorization Data Option (alt. Authentication Data Option)
===========================================================

This is the current Authentication Data Option.

Authenticator
=============

This is the MAC field in the Authorization Data Option.

Binding Acknowledgment
======================

This is the response to a Binding Update, or to an unknown MH Type.