Last update at http://inet.nttam.com : Thu May  4 12:36:21 1995

 Solutions of IPng Support for Wireless-ATM Integration

                                       Lu Wei     
                    Wireless-ATM Research Group
        Correspondence: DDKE0002@UTMKL.UTM.MY


Abstract

  One of the solutions to realize Wireless-ATM integration is to use
the TCPng/IPng, which is promising in the future global networks. 
Compared with the traditional TCP, TCPng will need to be developed
describing the new header fields and formats. It would contain support
for broadband wireless networks as well as ATM networks. In this
paper, the author proposes some solutions and aspects for the
Wireless-ATM implementation.

Keywords:  Internet, TCPng/IPng, Wireless-ATM, Internetworking, Router.

1. Introduction
  
  Wireless networks are becoming increasingly popular for network
applications since they eliminate the problems involved in cabling
within and across buildings in wired networks. The future integrated
services ( voice, data, video, etc ) environment needs broadband
networks. The latest developments in the wireless transmission
technology render wireless networks the capability to carry broadband
services. Providing broadband network capacity using wireless medium
can be accomplished by allocating a single high bandwidth channel for
all the users to share through an agreed channel access algorithm.
  To integrate the broadband wireless networks into the broadband
integrated service digital networks (B-ISDN) is an important and
valuable work, which involves many newest technologies, such as
Wireless ATM, broadband access, intelligent routing, wireless coding,
etc. However, research on this topic is full of challenge as well as
interest.
  When discussing about the above integrated networks, the broadband
wireless networks could be Infra-Red system, Millimeter wave in-door
system, satellite system or Laser system. That means the wireless
transmission bitrate can be lower (64Kb/s) or very higher ( >300
Mb/s). Also, the transmission bitrate of B-ISDN flow can be from
34Mb/s to 622Mb/s.  Meanwhile, the spectrum utilization of the
wireless networks is one of the most important aspects in considering
the integrated system. Firstly there is no enough wireless bandwidth
for the future large-capacity communication services. On the other
hand, in order to meet the increasing demand of broadband traffics,
wireless channel is an inevitable solution. That is to say, in the
research of the integrated system, an effective broadband coding,
error correction and frequency re-use scheme must be proposed to
ensure the system feasible.
  B-ISDN is the future trend of telecommunication networks. In this
network, Asynchronous Transfer Mode (ATM ) is the core not only in
transmission node, but also in switching node. Due to the attractive
features which ATM posseses, it is popularly used in many integrated
systems, such as ATM-LAN, ATM-MAN, etc. Besides, because the
transmission bitrate of ATM cells could be very high, it is regarded
as the future main backbone of broadband networks.

  In a word, the integration of broadband wireless network and B-ISDN
is of great significance to the broadband telecommunication networks. 
The concept " Wireless-ATM" has been becoming the new focus in the
communications.
  
 The author proposed two ways to realize the Wireless-ATM integration. 
One is to make use of the existing medium and interconnect the two
heterogeneous networks directly, such as "ATM Via Satellite", etc.
The other is to construct a common platform and make the integrated
system flexible to control and manage. This platform is the so-called
TCPng/IPng, which will be the Next Generation of Transport Control
Protocol (TCP) and Internet Protocol (IP). In this paper, the author
discusses some solutions for the second method of Wireless-ATM
implementation.

2. TA (Transport Address) for   TCPng/IPng Independence

  "The internet architecture, the grand plan behind the TCP/IP
protocol suite" was developed and tested in the late 1970s, and but
for the addition of subnetting, autonomous systems, and the domain
name system in the early 1980s and the more recent IP multicasting
implementation, stands today essentially unchanged. Even with the
understood benefits of a multi-layer protocol stack, all steps taken
to enhance the internet and its services have been very incremental
and narrowly focused.
  The reasons for change from IP to IPng can be described in terms of
problems for which the current IP will simply become inadequate and
unusable in the near future. These problems are the exhaustion of IP
address space in general, the non-hierarchical nature of address
allocation leading to a flat routing space, and the dependence of
TCP/IP.

  The OSI model specifies that each layer be independent of the
adjacent layers. What is specified in the interface between layers. 
This allows layers to be replaced and/or modified without making
changes to the other layers. As was pointed out previously, the TCP
and IP layers violate this precept.  TCP is highly dependent on the IP
netwprk layer for two very low level reasons: 1) a TCP socket is
formed by concatenating a network layer address ( IP address) and the
transport layer TCP port number. 2) included in the TCP checksum
calculation are the IP layer source and destination address mentioned
above which are transferred across the TCP/IP interfaces as procedure
call arguments. It should be noted at this point that the reason for
such strong dependence between the transport and network layers in
TCP/IP is to ensure a globally unique TCP layer address, so that a
unique connection could be identified by a pair of sockets. To
overcome the TCP's dependence on IP will require changes to the
structure of the TCP header.

  Meanwhile, someone proposed that the IP address requirement with TCP
be replaced with a globally unique transport address (TA) concatenated
with a transport layer port addrress. This solution offers the
capability to still maintain a globally unique address and host unique
port number with the added benefit of eliminating the transport and
network layer dependence on one another. Some of the goals defined in
developing this TA are:

  1. Fixed size ( A fixed size will make parsing easier for decoding
     stations.
  2. Minimum impact on TCP packet size ( This information will need to
     be carried in each TCP packet.
  3. Global Uniqueness ( It is desirable (required) to have a globally
     unique transport address.
  4. Automatic Registration ( To reduce implementation problems, an
     automatic registration of the TA is desirable.

  The TA will be used when an Internet node attempts to communicate
with another Internet node. Conceptually you can view the TA as
replacing the IP number in every instance it now appears in the
transport layer (i.e., a socket would change from IP#.port# to
TA#.port#). The author of this paper proposed a model for the design
of this TA and developed it for the Wireless-ATM implementation.
 
 3.  IPng over ATM

   This section describes parameters that are needed to map IPng (or
any protocol operating above the link level) to ATM services. ATM is a
"sophisticated" link level technology which provides the potential
capability for applications at the TCP/UDP level to map to a single
ATM virtual circuit for transport across an ATM network(s) customized
to the network performance and traffic requirements for that
application. This is a step above many of today's existing link
technologies which can only support a single level of network
performance that must be shared by all applications operating on a
single endpoint.
   The future Internet will be comprised of both conventional and
"sophisticated" link technologies.  The "sophisticated" features of
link layers like ATM need to be incorporated into an internet where
data travels not only across an ATM network but also several other
existing wireless network technologies. Future networks are likely to
be a combination of subnetworks providing best-effort link level
service and also sophisticated subnetworks that can support quality of
service-based connections like ATM.  One can envision data originating
from an WirelessNet, passing through an ATM network, FDDI network,
another ATM network, and finally arriving at its destination residing
on a HIPPI network. IPng packets will travel through such a list of
interconnected network technologies as ATM is incorporated as one of
the components of the future Internet.
   To support per application customizable link level connections,
four types of ATM information should be derivable from the higher
level protocol(s) like IPng. This ATM information includes: source and
destination ATM addresses, connection quality of service parameters,
connection state, and an ATM virtual circuit identifier which maps to
a single IPng application (i.e., single TCP/UDP application). Some of
these mapping could potentially be derivable through information
provided by proposed resource reservation protocols supporting an
integrated services Internet.  However, the ATM virtual circuit
identifier needs to be efficiently mappable from IPng packet
information.

 Characteristics of ATM Service

   ATM has several characteristics which differentiates it from
current link level technologies.  First of all, ATM has the capability
of providing many virtual channels to transmit information over a
single wire (or fiber). This is very similar to X.25, where many
logical channels can be established over a single physical media. But
unlike X.25, ATM allows for each of these channels or circuits to have
a customizable set of performance and quality of service
characteristics. Link level technologies like Ethernet provide a
single channel with a single performance and quality of service
characteristic. In a sense, a single ATM link level media appears like
an array of link level technologies each with customizable
characteristics.
   ATM virtual circuits can be established dynamically utilizing its
signaling protocol. ATM signaling is a source initiated negotiation
process for connection establishment. This protocol informs elements
in the network of the characteristics for the desired connection. ATM
signaling does not provide any guidelines for how network elements
decide whether it can accept a call or where a signaling request
should be forwarded if the end destination (from the link level
perspective) has not been reached. In short, ATM signaling does not
support any routing functionality of network admission control.
   ATM signaling establishes a "hard state" in the network for a call. 
"Hard state" implies that the state of a connection in intermediate
switching equipment can be set and once established it will be
maintained until a message is received by one of the ends of the call
requesting a change in state for the connection. As a result, an ATM
end system (this could be a workstation with an ATM adapter or a
router with an ATM interface) receives guaranteed service from the ATM
network. The ATM network is responsible for maintaining the connection
state. The price the ATM termination points pay for this guarantee is
the responsibility of changing the state of the connection,
specifically informing the ATM network to establish, alter, or
tear-down the connection.
   Each ATM end point in a network has an ATM address associated with
it to support dynamic connection establishment via signaling. These
addresses are hierarchical in structure and globally unique. As a
result, these addresses are routable. This allows ATM networks to
eventually support a large number of ATM endpoints once a routing
architecture and protocols to support it become available.
   The ATM User-Network Interface (UNI) signaling protocol based on
ITU-TS Q.93B allows many different service parameters to be specified
for describing connection characteristics. These parameters can be
grouped into several categories: ATM adaptation layer (AAL)
information, network QOS objectives, connection traffic descriptor,
and transit network selector. The AAL information specifies negotiable
parameters such as AAL type and maximum packet sizes. The network QOS
objectives describe the service that the ATM user expects from the
network. Q.93B allows for one of five service classes to be selected
by the ATM user. The service classes are defined as general traffic
types such as circuit emulation (class A), variable bit rate audio and
video (class B), connection-oriented data transfer (class C),
connectionless data transfer (class D), best effort service (class X),
and unspecified. Each of these categories are further specified
through network provider objectives for various ATM performance
parameters. These parameters may include cell transfer delay, cell
delay variation, and cell loss ratio. The connection traffic
descriptor specifies characteristics of the data generated by the user
of the connection. This information allows the ATM network to commit
the resources necessary to support the traffic flow with the quality
of service the user expects. Characteristics defined in the ATM Forum
UNI specification include peak cell rate, sustainable cell rate, and
maximum and minimum burst sizes.
   Lastly, the transit network selection parameter allows an ATM user
to select a preferred network provider to service the connection.

  Parameters Required to Map IPng to ATM

   There are several parameters required to map ATM services from a
higher level service like IPng. These ATM parameters can be
categorized in the following manner: addressing parameters, connection
QOS-related parameters, connection management information, and ATM
virtual circuit identifier. The first three categories provide support
for ATM signaling. The last parameter, a connection identifier that
maps IPng packets to ATM virtual circuits, provides support for an ATM
virtual circuit per application when the end-to-end connection travels
across an ATM subnetwork(s) (this does not assume that ATM is the only
type of subnetwork that this connection travels across). Below,
mapping issues for each of these parameters will be described.

a. Addressing

   ATM supports routable addresses to each ATM endpoint to facilitate
the dynamic establishment of connections. These addresses need to be
derived from a higher level address such as an IPng address and IPng
routing information.  This type of mapping is not novel. It is a
mapping that is currently done for support of current IP over link
technologies such as Ethernet.  An IP over ATM address resolution
protocol (ARP) has been described in the Internet Standard, "Classical
IP over ATM". In addition, support for IP routing over large ATM
networks is being worked in the IETF's "Routing over Large Clouds"
working group.

b. Quality of Service

   As described before, an ATM virtual circuit is established based
upon a user's traffic characteristics and network performance
objectives. These characteristics which include delay and throughput
requirements can only be defined by the application level (at the
transport level or above) as opposed to the internetworking (IPng)
level. For instance, a file transfer application transferring a 100 MB
file has very different link level performance requirements than a
network time application. The former requires a high throughput and
low error rate connection whereas the latter could perhaps be
adequately serviced utilizing a best-effort service. Current IP does
not provide much support for a quality of service specification and
provides no support for the specification of link level performance
needs by an application directly. This is due to the fact that only a
single type of link level performance is available with link
technologies like Ethernet.  As a result, all applications over IP
today receive the same level of link service.

   IPng packets need not explicitly contain information parameters
describing an application's traffic characteristics and network
performance objectives (e.g., delay = low, throughput = 10 Mb/s).

c.  Connection Management

   The establishment and release of ATM connections should ultimately
be controlled by the applications utilizing the circuits. Currently,
IP provides no explicit mechanism for link level connection
management.
   Future support for link level connection management could be
accomplished through resource reservation protocols and need not
necessarily be supported directly via information contained in the
IPng protocol.

d. Connection Identifier

   A mapping function needs to exist between IPng packets and ATM so
that application flows map one-to-one to ATM virtual circuits. 
Currently, application traffic flows are identified at the transport
level by UDP/TCP source and destination ports and IP protocol
identifiers.  This level of identification should also be available at
the IPng level so that information in the IPng packets identify an
application's flow and map to an ATM virtual circuit supporting that
flow when the IPng packets travels across an ATM subnetwork(s).
   Using the current IP protocol, identifying an application's traffic
flow requires the combination of the following five parameters: source
and destination IP addresses, source and destination UDP/TCP ports,
and IP protocol identifier. This application connection identifier for
IP is complex and could potentially be costly to implement in IP end
stations and routers.  The IPng connection identifier should be large
enough so that all application level traffic from an IPng end point
can be mapped into the IPng packet.
   Currently, ATM provides 24 bits for virtual circuit identification
(VPI and VCI). This provides sufficient capacity for 2^24 (16,777,216)
connections. The actual number of bits that are used for the ATM
virtual circuit however is established through negotiation between the
ATM endpoint and ATM network. This number is useful as an upper bound
for the number of mappings that are needed to be supported by IPng.
   An IPng candidate should be able to identify how IPng packets from
an application can map to an ATM virtual circuit. In addition, this
mapping should be large enough to support a mapping for every IPng
application on an end system to an ATM virtual circuit. Careful
consideration should be given to complexity of this mapping for IPng
to ATM since it needs to eventually support gigabit/sec rates.

4.  IPng  Wireless Interconnection

   Current versions of the Internet Protocol make an implicit
assumption that a node's point of attachment remains fixed.  Datagrams
are sent to a node based on the location information contained in the
node's IP address.
   If a node moves while keeping its IP address unchanged, its IP
network number will not reflect its new point of attachment.  The
routing protocols will not be able to route datagrams to it correctly.
   A number of considerations arise for routing these datagrams to a
Wireless Node.

Addressing

   Each Wireless Node must have at least one Home-Address which
identifies it to other nodes.  This Home-Address must be globally
unique.

Ownership

   The presence of ownership information in the Home-Address would be
beneficial.  A Wireless Node will be assigned a Home-Address by the
organization that owns the machine, and will be able to use that
Home-Address regardless of the current point of attachment.
   The ownership information must be organized in such a fashion to
facilitate "inverse" lookup in the Domain Name Service, and other
future services. Ownership information could be used by other nodes to
ascertain the current topological location of the Wireless Node. 
Ownership information could also be used for generation of accounting
records.

Topology

   There is no requirement that the Home-Address contain topological
information.  Indeed, by the very nature of mobility, any such
topological information is irrelevant.
   Topological information in the Home-Address must not hinder
mobility, whether by prevention of relocation, or by wasting bandwidth
or processing efficiency.
   In order that transport connections be maintained while roaming,
topological changes must not affect transport connections.
   For correspondent nodes which do not implement wireless functions,
topological changes should not be communicated to the correspondent.
   For correspondent nodes which implement wireless functions, the
correspondent should be capable of determining topological changes.
   Topological change information must be capable of insertion and
removal by routers in the datagram path, as well as by the
correspondent and Wireless Node.

Numbering

   The number of wireless nodes is expected to be constrained by the
population of users within the lifetime of the IPng protocol.  The
maximum world-wide sustainable population is estimated as 16e9,
although during the lifetime of IPng the population is not expected to
exceed 8e9.
   Each user is assumed to be mobile, and to have a maximum combined
personal mobile and home network(s) on the order of 4e3 nodes.
   The expectation is that only 46 bits will be needed to densely
number all mobile and home nodes.
 The size of addressing elements is also constrained by bandwidth
efficiency and processing efficiency, as described later.

Configuration

   Since the typical user would be unlikely to be aware of or willing
and able to maintain 4e3 nodes, the assignment of Home-Addresses must
be automatically configurable.  Registration of the nodes must be
dynamic and transparent to the user, both at home and away from home.

Communication

   A Wireless Node must continue to be capable of communicating
directly with other nodes which do not implement wireless functions.
   No protocol enhancements are required in hosts or routers that are
not serving any of the wireless functions.  Similarly, no additional
protocols are needed by a router (that is not acting as a Home Agent
or a Foreign Agent) to route datagrams to or from a Wireless Node.
   A Wireless Node using its Home-Address must be able to communicate
with other nodes after having been disconnected from the Internet, and
then reconnected at a different point of attachment.
   A Wireless Node using its Home-Address must be able to communicate
with other nodes while roaming between different points of attachment,
without loss of transport connections.

Routing Updates

   Wireless Nodes are expected to be able to change their point of
attachment no more frequently than once per second.
   Changes in topology which occur more frequently must be handled at
the link layer transparently to the internetwork layer.  It is further
noted that engineering margins may require the link layer to handle
all changes at a frequency in the neighborhood of 10 seconds.
   Changes in topology which occur less frequently must be immediately
reflected in the wireless updates.  This may preclude the use of the
Domain Name Service as the repository of wireless topological
information.
   It must be noted that global routing updates do not operate at this
frequency.  As old topological information may be obsoleted faster
than global routing updates, access to the repository of wireless
topological information must be independent of prior topological
information.
   The wireless specific repository should use ownership information
in the Home-Address for access to the repository.

Path Optimization

   Optimization of the path from a correspondent to a wireless node is
not required.  However, such optimization is desirable.
   For correspondent nodes which implement wireless functions, the
correspondent should be capable of determining the optimal path.
   The optimization mechanism is also constrained by security,
bandwidth efficiency and processing efficiency, as described later.

Security

a.  Authentication

   Wireless registration messages must be authenticated between the
home topological repository and Wireless Node.
   When the correspondent implements wireless functions, redirection
or path optimization must be authenticated between the correspondent
and Wireless Node.

b.  Anonymity

   The capability to attach to a foreign administrative domain without
the awareness of the foreign administration is not prohibited. 
However, any wireless mechanism must provide the ability to prevent
such attachment.

c.  Location Privacy

   The capability to attach to a foreign administrative domain without
the awareness of correspondents is not prohibited.  However, any
wireless mechanism must provide the ability for the home
administration to trace the current path to the point of attachment.

d. Content Privacy

   Security mechanisms which provide content privacy must not obscure
or have a dependency on the topological location of Wireless Nodes.

Bandwidth

   Wireless must operate in the current link environment, and must not
be dependent on bandwidth improvements.  The Wireless Node's directly
attached link is likely to be bandwidth limited.
   In particular, wireless frequency spectrum is already a scarce
commodity.  Higher bandwidth links are likely to continue to be scarce
in the wireless environment.
   Current applications of wireless links include HF links which are
subject to serious fading and noise constraints, VHF and UHF line of
sight radio between ships or field sites, UHF Satellite Communications
links, and Millimeter wave in-door broadband channels.
   It appears likely that satellite-based PCS will be widely deployed
for basic telephony communications in many newly-industrialized and
lesser-developed countries.  There is already significant PCS interest
in East and SouthEast Asia, India, and South America.

Administrative Messages

   The number of administrative wireless messages sent or received by
the Wireless Node must be limited to as few as possible.  In order to
meet the frequency requirement of changing point of attachment once
per second, registration of changes must not require more than a
single request and reply.
   The size of administrative wireless messages must be kept as short
as possible.  In order to meet the frequency requirement of changing
point of attachment once per second, the registration messages must be
not more than 120 bytes for a complete transaction, including link and
internet headers.

Response Time

   For most wireless links in current use, the typical TCP/IPv4
datagram overhead of 40 bytes is too large to maintain an acceptable
typing response of 200 milliseconds round trip time.
   Therefore, the criteria for Wireless IPng is that the response time
not be perceptably worse than IPv4. This allows no more than 6 bytes
of additional overhead per datagram to be added by IPng.
   This was a primary concern in the design of wireless forwarding
headers.  Larger headers were rejected outright, and negotiation is
provided for smaller headers than the default method.
   Topological headers are removed by the Foreign Agent prior to
datagram transmission over the slower link to the Wireless Node, which
also aids header prediction, as described below.

Header Prediction

   Header prediction can be useful in reducing bandwidth usage on
multiple related datagrams.  It requires a point-to-point peer
relationship between nodes, so that a header history can be maintained
between the peers.
   Header prediction is less effective in wireless environments, as
the header history is lost each time a Wireless Node changes its point
of attachment.  The new Foreign Agent will not have the same history
as the previous Agent.
   In order for header prediction to operate successfully, changing
topological information must be removed from datagram overhead prior
to transmission of the datagram on any final hop's directly attached
link.  This applies to both the Wireless Node peering with a Foreign
Agent, and also the final link to a Correspondent.  Otherwise, header
prediction cannot be relied upon to improve bandwidth utilization on
low-speed Wireless and Correspondent links.
   Since the changing topological information cannot be removed in the
forwarding path of the datagram, header prediction will also be
affected at any other pair of routers in the datagram path.  Each time
that a Wireless Node moves, the topological portion of the header will
change, and header history used at those routers will be updated.
Unless topological information is limited to as few headers as
possible, this may render header prediction ineffective as more
Wireless Nodes are deployed.

Mobility

  In some cases, the wireless subnet will perform its own routing and
management of this dynamic topology.  This will be invisible to the
internet protocol except for (hopefully) subtle changes to some
routing metrics (e.g., more or less delay to reach a host).  In this
instance, the wireless subnetwork protocols serve as a buffer to the
internet routing protocols and IPng will not need to be too concerned
with mobility.
   In other cases, however, the platform may make a dramatic change in
position and require a major change in internet routing.  IPng must be
able to support this situation.  It is recognized that an internet
protocol may not be able to cope with large, rapid changes in
topology.  Efforts will be made to minimize the frequency of this in a
wireless communication architecture, but there are instances when a
major change in topology is required.
   Furthermore, it should be realized that mobility in the setting is
not limited to individual nodes moving about, but that, in some cases,
entire subnetworks may be moving.  An example of this is a Navy ship
with multiple ATM Beds on board, moving through the domains of
different wireless networks.  In some cases, the wireless subnet will
be moving, as in the case of an aircraft strike force, or Navy
battlegroup.

Flows and Resource Reservation

   The tactical military has very real requirements for multi-media
services across its shared and inter-connected Wireless networks.
This includes applications from digital secure voice integrated with
applications such as "white boards" and position reporting for mission
planning purposes to low-latency, high priority tactical data messages
(target detection, identification, location and heading information).
Because of the limited capacity of tactical wireless networks,
resource reservation is extremely important to control access to these
valuable resources.  Resource reservation can play a role in
"congestion avoidance" for these limited resources as well as ensuring
that quality-of-service data delivery requirements are met for
multi-media communication.
   Note there is more required here than can be met by simple
quality-of-service (QoS) based path selection and subsequent
source-routing to get real-time data such as voice delivered.  For
example, to support digital voice in the CSNI project, a call setup
and resource reservation protocol was designed.  It was determined
that the QoS mechanisms provided by the CLNP specification were not
sufficient for our voice application path selection.  Voice calls
could not be routed and resources reserved based on any single QoS
parameter (e.g., delay, capacity, etc.) alone.  Some wireless subnets
in the CSNI test bed simply did not have the capability to support
voice calls.
   To perform resource reservation for the voice calls, the CLNP cost
metric was "hijacked" as essentially a Type of Service identifier to
let the router know which datagrams were associated with a voice call.
The cost metric, concatenated with the source and destination
addresses were used to form a unique identifier for voice calls in the
router and subnet state tables.  Voice call paths were to be selected
by the router (i.e. the "cost" metric was calculated) as a rule-based
function of each subnet's capability to support voice, its delay, and
its capacity.  While source routing provided a possible means for
voice datagrams to find their way from router to router, the network
address alone was not explicit enough to direct the data to the
correct interface, particularly in cases where there were multiple
communication media interconnecting two routers along the path.
Fortunately, exclusive use of the cost QoS indicator for voice in CSNI
was able to serve as a flag to the router for packets requiring
special handling.
   While a simple Type of Service field as part of an IPng protocol
can serve this purpose where there are a limited number of well known
services, a more general technique such as RSVP's Flow Specification
can support a larger set of such services.  And a field, such as the
one sometimes referred to as a Flow Identification (Flow ID), can play
an important role in facilitating inter-networked data communication
over these limited capacity networks.
   For example, the D/V ATD wireless sub-network provides support for
both connectionless datagram delivery and virtual circuit
connectivity. To utilize this capability, an IPng could establish a
virtual circuit connection across this wireless subnetwork which meets
the requirements of an RSVP Flow Specification. By creating an
association between a particular Flow ID and the subnetwork header
identifying the established virtual circuit, an IPng gateway could
forward data across the low-capacity while removing most, if not all,
of the IPng packet header information.  The receiving gateway could
re-construct these fields based on the Flow Specification of the
particular Flow ID/virtual circuit association.  In summary, a field
such as a Flow Identification can serve at least two important
purposes:
   1) It can be used by routers (or gateways) to identify packets with
special, or pre-arranged delivery requirements.  It is important to
realize that it may not always be possible to "peek" at internet
packet content for this information if certain security considerations
are met (e.g., an encrypted transport layer).
  2) It can aid mapping datagram services to different types of
communication services provided by specialized subnet/data link layer
protocols.
 
Multicast

   Wireless communication has a very clear requirement forulticast. 
For example, efficient dissemination of information to distributed
participants can be the key to success in a battle.  In modern
warfare, this information includes imagery, the "tactical scene" via
tactical data messages, messaging information, and real-time
interactive applications such as digital secure voice.  Many of the
tactical wireless communication media are broadcast by nature, and
multicast routing can take advantage of this topology to distribute
critical data to a large number of participants.  The throughput
limitations imposed by these wireless media and the physics of
potential electronic counter measures (ECM) dictate that this
information be distributed efficiently.  A multicast architecture is
the general case for information flow in a tactical internetwork.

Quality of Service and Policy-Based Routing

   Quality of service and policy based routing are of particular
importance in some environment with limited communication resources,
limited bandwidth, and possible degradation and/or denial of service.
Priority is a very important criteria in this setting.  In some
wireless world of limited resources (limited bandwidth, radio assets,
etc.) there will be instances when there is not sufficient capacity to
provide all users with their perception of required communication
capability.  It is extremely important for a shared, automated
communication system to delegate capacity higher priority users.
Unlike the commercial world, where everyone has a more equal footing,
it is possible in the military environment to assign priority to users
or even individual datagrams.  An example of this is the special data
exchange.  Special data messages are generally single-datagram
messages containing information on the location, bearing,
identification, etc., of entities detected by sensors.  In CSNI,
special data messages were assigned 15 different levels of CLNP
priority.  This ensured that important messages were given priority
over less important messages.

Applicability

   There will be a significant amount of applicability to wireless
networks.  The current IP and CLNP protocols are being given
considerable attention in the wireless community as a means to provide
communication interoperability across a large set of heterogeneous
wireless networks in use by different services and countries.  The
applicability of IPng can only improve with the inclusion of features
critical to supporting QoS and Policy based routing, security,
real-time multi-media data delivery, and extended addressing.  It must
be noted that it is very important that the IPng protocol headers not
grow overly large.  There is a sharp tradeoff between the value added
by these headers (interoperability, global addressing, etc.) and the
degree of communication performance attainable on limited capacity
wireless networks.

Datagram Service

   The datagram service paradigm provides many useful features for
tactical communication networks.  The "memory" provided by datagram
headers, provides an inherent amount of survivability essential to the
dynamics of some communication environment. The efficiency with which
multi-cast can be implemented in a connectionless network is highly
critical in some environment where rapid, efficient information
dissemination can be a deciding factor.  And, as has been proven, with
several different Internet applications and experiments, a datagram
service is capable of providing useful connection-oriented and
real-time communication services.
   Consideration should be given in IPng to how it can co-exist with
other architectures such as switching fabrics which offer demand-based
control over topology and connectivity. Standard management (SNMP,
etc.) is of course useful here, but wireless communication media can
be somewhat dynamically allocated. Dial-up IP routing is an example of
an integrated solution.  The IPng should be capable of supporting a
similar type of operation.

Support of Communication Media

   The communication environment includes a very broad spectrum of
communication media.  Many of the wireless links, even higher speed
ones, can exhibit error statistics not necessarily well-serviced by
higher layer reliable protocols (i.e., TCP).  In these cases,
efficient lower layer protocols can be implemented to provide reliable
datagram delivery at the link layer, but at the cost of highly
variable delay performance.
   It is also important to recognize that wireless communication
cannot be viewed from the IPng designer as simple point-to-point
links. Often, highly complex, unique subnetwork protocols are utilized
to meet requirements of survivability, communications performance with
limited bandwidth, anti-jam and/or low probability of detection
requirements.  In some of these cases IPng will be one of several
Layer 3 protocols sharing the subnetwork.
   It is understood that IPng cannot be the panacea of Layer 3
protocols, particularly when it comes to provide special mechanisms to
support the endangered-specie low data rate user.  However, note that
there are many valuable low data rate applications useful to some
users.  And low user data rates, coupled with efficient networking
protocols can allow many more users share limited wireless bandwidth.
As a result, any mechanisms which facilitate compression of network
headers can be considered highly valuable in an IPng candidate.

5. Implementation

 In order to design the integrated system, some solutions should be
adopted according to the above discussion.
	. By using Cooperative Parallel Expert-system (CPE), we have
          successfully designed the TA Embedded Board for the TCPng/IPng
          independence[1].
	. By using Neural Network, we realize the Datagram Forwarding
          Algorithm in a much flexible way[3]. This means that the IPng Router
          can be designed intelligently based on the IP Router.
	. Through using TCPng/IPng, the Wireless-ATM system management
          can be simple and standard.  With SNMP (Simple Network Management
          Protocol), we defined the Managed Objects for the Wireless-ATM
          management in our Test-bed.
      The detailed design of the system can be obtained by contacting
the author directly.


6. Conclusion

  Wireless-ATM and TCPng/IPng are the newest technologies in the
telecommunication fields. All these ideas are for the Future Global
Communication Trends. Through 3 years research on this topic, we found
the above methods are the feasible solution to the implementation of
the integrated system. However, in order to varify the practical
performance using our method, much works are being undertaken in the
real test bed. In the near future, we will also entend our solutions
to some famous international nodes for on-site testing.


Reference

1. W.Lu. V-Language: A New Rule Based Programming Language for
   Real-time Application, International Conference on Information
   Processing, New Orlean, USA, Nov.9-11, 1994.

2. W.Lu, I.Ishak. Research on the Integration of Mobile Network and
   the ATM Network, PTC'95, Jan 22-26, 1995. Honolulu, USA.

3. W.Lu. Analysis of Neural Network Routing Scheme for
   Telecommunication Network, IEICE Trans. on Communications. ( will be
   published)

4. W.Lu. DQCA: A New Medium Access Control Protocol for Broadband
   Networks, 7th IEEE LAN/MAN Workshop, Mar 26-29, 1995. Florida.

5. RFC Documentations.

6. W.Lu. Wireless-ATM Research Reports.  University of Technology
   Malaysia and Wireless-ATM Research Group, 1994.