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In this paper, several performance measurements of ATM (Asynchronous Transfer Mode) networks are performed and analysed. Especially, measurement of the buffer size, the traffic management functions and the cell transfer delay in a switching system are studied as a function of various traffic patterns and loading levels. These values have great importance for establishing reliable media for broadband traffic and contributing to the implementation of services in ATM networks.
ATM has been under a thorough standardization process for more than ten years. Looking at it now, what have we achieved during this time period? Originally ATM was meant to be an easy and an efficient protocol enabling varying services over a single network. What it is turning to be is ‘yet another ISDN’-- network full of hopes and promises but too difficult to implement and expensive to market. The fact is that more and more ‘nice features’ are implemented on the cost of overloading network with hard management procedures. Therefore we need to adopt a new approach. This approach keeps a strong reminds on ‘what is necessary.' This paper presents starting points for an alternative approach to the traffic management. We refer to this approach as ‘the minimum management principle.' Choosing of the suitable service classes for the ATM network is made difficult by the fact that the more services one implements the more management he needs. This is especially true for the variable bit rate connections that are usually treated based on the stochastic models. Stochastic model, at its best, can only reveal momentary characteristics in the traffic stream not the long range behavior of it. Our assumption is that ATM will move towards Internet in the sense that strict values for quality make little or no sense in the future. Therefore stochastic modeling of variable bit rate connections seems to be useless. Nevertheless we see that some traffic needs to have strict guarantees and that only economic way of doing so is to use PCR allocation.
One of the most important network elements in the Internet are the routers which do relaying of IP packets. Because of growth of the Internet routers currently experience serious problems in relaying traffic in a satisfying speed. The idea of switching Internet traffic flows has recently been introduced and a new technology called IP switching has emerged. Several differing technological solutions have been suggested. In this paper we describe and compare two methods in flow-based IP switching to make the decisions whether to switch internet traffic flows to separate ATM-connections. Traffic measurements are made in two networks of varying size and based on a specific three-stage flow analysis we suggest that the decision to switch should be made as flexible as possible due to the expected diversity of traffic profiles in different parts of the network. This way the optimal service cluster could be switched and router resources could be optimally utilized. A simple model to determine workload to an IP switch is introduced. Using this model we see that the workload of the flow setup component and the routing component may be optimized, if we use flexible methods to determine the flows that are to be separately switched.
Key issues in the current development of Internet seem to be its capability
to scale and to support new real-time or near real-time applications like
video- and audio conferencing. There are two factors that affect these
qualities: one is the ability to distinguish which connections should be
switched and the other is the effective control over network resources.
ATM is a serious attempt to standardize global multiservice networks. This
attempt seems to suit well for the future Internet. ATM was originally
meant to be an easy and an efficient protocol but it is now turning to
be ‘yet another ISDN’. More and more features are implemented to ATM resulting
in the overloading of the network with management procedures. Therefore
a new approach needs to be taken. In this approach a strong reminder of
‘what is necessary’ needs to be kept in mind. This paper presents an alternative,
simpler approach to the ATM traffic management and introduces some suggestions
how to map Internet applications to simplified ATM environment using an
advanced IP switching concept.
This paper describes and analyses a solution to the problem of interoperability between Intelligent Networks and Voice over IP networks for directory-based routing. We will present an architecture based on a distributed database on the circuit switched network and the IP network. The aim of the solution is to provide efficient service management, efficient routing for 800- and cellular numbers and personal number portability between both architectures. As an introduction, some directory-based solutions for number portability are presented and especially the requirements for a directory-based routing solution are discussed. Arguments for and against using directories and some design issues are presented. We then develop and present an infrastructure for directory-based routing that in addition to number portability also provides efficient service management and routing in a hybrid (SCN, IP voice) network. This paper is mainly intended as a framework of a project under development in our Laboratory.
The solution is based on different approaches for each network. In the IP network we use the Telephony Routing over IP (TRIP) protocol developed by IETF. Additionally, the described architecture is open for inclusion of the Enum protocol that is under development. For the circuit switched network, we suggest a new protocol called Circuit Telephony Routing Information Protocol (CTRIP). The protocol provides a distributed method for synchronizing routing information between databases located in the SDFs. Furthermore, we define the operation of numbering gateways, which are used for transferring number information between the two network types. The numbering gateway functionality is intended as a logical entity in the gateway decomposition model. Due to the different needs in circuit switched networks and IP networks, also the number portability information differs. Precisely defined algorithms are required for mapping information between the protocols to avoid routing loops and inefficient routing. We utilize the Server Cache Synchronization Protocol (SCSP) as the common element for data synchronization and replication for distributed entities.
For Number Portability it is essential to use and maintain data that
is shared among many applications while the data resides in different physical
locations. The introduction of Voice over IP services increases the requirements
for managing large amounts of data. To facilitate user mobility, the data
is distributed over different locations following directory structures
where the information is close to the customer location. The main goal
is to achieve a service that is accessible from everywhere, independently
of the location of the user accessing the service. For that reason, we
are implementing the TRIP and CTRIP based on the SCSP. In this paper its
actual development is discussed. We point out the final application for
the whole solution in a mixed IP/ISDN network. We also review some alternative
approaches to directory services. In conclusion we propose the SCSP as
the basic component for exchanging information about portable numbers between
IN and IP. We want to emphasize the key role of synchronizing and updating
the user information in the emerging global communications infrastructure.
In this paper, we present the design and implementation of a new QoS_based
Routing Simulator (QRS). Based on the core of a public routing simulator
– MaRS , we have developed QRS by designing and implementing new
QoS-related components, i. e., resource reservation (RSVP), resource management
(RM), QoS routing algorithms, traffic scheduling and real-time traffic
workload. QRS allows users to configure the parameters of a QoS guaranteed
network, where the dynamics of QoS routing algorithms as well as traffic
management algorithms can be investigated. We also present some simulation
results obtained by using QRS.
In order to provide various services with different quality requirements,
the current Internet is expected to turn into a QoS based Internet under
the Differentiated Service (DiffServ) architecture. A variety of works
have been done in the field of constraint based routing to provide
QoS guaranteed or assured services by developing novel routing protocols
and algorithms. However, most of these efforts focus on intra-domain routing
rather than inter-domain routing. In this paper, we discuss issues of finding
routes with QoS requirements among multiple domains, called inter-domain
QoS routing. We first investigate the needs and problems faced when introducing
inter-domain QoS routing into the Internet. Then, we present a model for
inter-domain QoS routing and describe its building blocks. Finally, we
present five mechanisms for operating inter-domain QoS routing in
Recently MPLS is used for building up VPNs in IP backbone, called MPLS
VPNs. In this paper, we discuss issues on finding routes with QoS requirements
(i.e., QoS routing) in MPLS VPNs. We first present background on MPLS VPNs
as well as QoS routing. Then we discuss both the benefits and problems
resulted from introducing QoS routing into MPLS VPNs. We particularly present
an architecture of MPLS VPNs with QoS routing capability, on which we discuss
some important issues on running QoS routing in MPLS VPNs.
Keywords: ATM, B-ISDN, IP-switching, internet, traffic measurements, routing
Keywords: C++,SNMP, MIB, SG,UNIX
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