Browse Prior Art Database

Use of the PPAR Scope to Implement IP over Mobile ATM

IP.com Disclosure Number: IPCOM000014851D
Original Publication Date: 2001-Apr-13
Included in the Prior Art Database: 2003-Jun-20
Document File: 3 page(s) / 88K

Publishing Venue

IBM

Abstract

1. Introduction

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Use of the PPAR Scope to Implement IP over Mobile ATM

1. Introduction

The mobility of ATM networks is specified by the ATM Forum with
the PNNI mobility extensions. The mechanism allows the logical
group node abstracting a mobile ATM network to roam in the PNNI
hierarchy of the terrestrial backbone network. Routing
information about the current location of a mobile network, is
advertised through regular PNNI, thus enabling the setup of calls
from a ground end-system to an end-system on board of a mobile
platform and vice-versa.

The implementation of the an ATM rerouting mechanism for SVCs in
addition to the PNNI mobility extensions, makes the complete
handling of mobility at layer 2 ATM possible.

Proxy Par, also specified at the ATM Forum, allows upper layer
protocols (e.g. IP) to register information and get this
information flooded by the PNNI protocol. Proxy Par has been
designed to allow IP routers at the edge of an ATM cloud to learn
about each other, thus avoiding manual configuration of the IP
adjacencies of the routers. Routers can register their layer
protocol information (e.g. IP address, ATM address, OSPF area) to
their serving ATM switch, which floods the information throughout
the ATM network. Other routers can retrieve this information by
querying their serving ATM switches and initiate for example a
BGP session based on the IP and ATM address learned. Proxy Par
allows a router to indicate a scope when registering information.
The piece of information registered is flooded within the ATM
network, up to the PNNI level matching the scope specified.

2. IP over mobile ATM

In a mobile environment the layer 3 IP protocol, can be logically
configured as a fixed IP network, relying on the ATM layer to
handle all the mobility aspects.

However, this configuration can lead to sub-optimal routing at
the IP layer. Because the IP layer is not aware of the mobility,
two IP routers can be logically directly linked, even though the
SVC linking the two routers runs around half of the earth.

To avoid this routing inefficiency, it is proposed that the
routers on board of a mobile platform build dynamically
adjacencies with routers geographically close to the current ATM
access points of the mobile network. When the mobile platform
moves and changes of access point, the routers build new
adjacencies, to the routers that are local to the ar...