Reservation Models, From Arequipa to SRP

We analyse and illustrate two approaches that we have developed for providing reservations to flows. The first approach uses the explicit reservation model: a traffic profile is negotiated between users and the network. ATM and RSVP are two examples for this approach. In this paper we describe our experience in the ACT project EXPERT (AC094) with the explicit reservation model in the context of ATM. We show that the integration of ATM in a TCP/IP oriented operating system is easy and does not require developing applications specially for ATM. The method we have designed is called Arequipa and is described in RFC 2170. It is fully implemented in Linux. However, we are confronted with the complexity required to support a single reservation for each flow. Our analysis is that it is well suited for segregating flows in applications such as private virtual networks, but that, for multimedia networks, the cost of handling a large number of flows is too high. This and other factors led us to develop an alternative solution, based on an implicit reservation model. Our solution is called the Scalable Reservation Protocol (SRP). SRP aggregates flows inside the network: routers other than edge routers performing policing do maintain only aggregate information per port. SRP is being developed and implemented in the framework of the ACTS project DIANA (AC319). Keywords: QoS; Aggregation; Arequipa; ATM; IP; SR

Quality of Service Renegotiations

Giving users simple access to QoS selection capability of ATM networks is important for the future of integrated services networks. We describe the first instance of an application in which users had the capacity to tune ATM traffic parameters with a button, at run time. To achieve this we implemented the necessary signaling extension on ATM switches as well as on end-systems. Furthermore, we extended Arequipa (Application REQested IP over ATM; a mechanism that enables applications to request direct ATM connections for their exclusive use and to directly control their traffic parameters) to support modification, and modified the popular Mbone tool Vic (VIdeo Conferencing) to use Arequipa to request and modify ATM bandwidth at will. We describe how Vic accomplished this over the ATM WAN of SWISSCOM, transferring live video from Lausanne to Basel over switched, renegotiable ATM connections

IP and ATM - a position paper

This paper gives a technical overview of different networking technologies, such as the Internet, ATM. It describes different approaches of how to run IP on top of an ATM network, and assesses their potential to be used as an integrated services network

IP and ATM - current evolution for integrated services

Current and future applications make use of different technologies as voice, data, and video. Consequently network technologies need to support them. For many years, the ATM based Broadband-ISDN has generally been regarded as the ultimate networking technology, which can integrate voice, data, and video services. With the recent tremendous growth of the Internet and the reluctant deployment of public ATM networks, the future development of ATM seems to be less clear than it used to be. In the past IP provided (and was though to provide) only best effort services, thus, despite its world wide diffution, was not considered as a network solution for multimedia application. Currently many of the IETF working groups work on areas related to integrated services, and IP is also proposing itself as networking technology for supporting voice, data, and video services. This paper give a technical overview on the competing integrated services network solutions, such as IP, ATM and the different available and emerging technologies on how to run IP over ATM, and tries to identify their potential and shortcomings

Renegotiable VBR service

In this work we address the problem of supporting the QoS requirements for applications while efficiently allocating the network resources. We analyse this problem at the source node where the traffic profile is negotiated with the network and the traffic is shaped according to the contract. We advocate VBR renegotiation as an efficient mechanism to accommodate traffic fluctuations over the burst time-scale. This is in line with the Integrated Service of the IETF with the Resource reSerVation Protocol (RSVP), where the negotiated contract may be modified periodically. In this thesis, we analyse the fundamental elements needed for solving the VBR renegotiation. A source periodically estimates the needs based on: (1) its future traffic, (2) cost objective, (3) information from the past. The issues of this estimation are twofold: future traffic prediction given a prediction, the optimal change. In the case of a CBR specification the optimisation problem is trivial. But with a VBR specification this problem is complex because of the multidimensionality of the VBR traffic descriptor and the non zero condition of the system at the times where the parameter set is changed. We, therefore, focus on the problem of finding the optimal change for sources with pre-recorded or classified traffic. The prediction of the future traffic is out of the scope of this thesis. Traditional existing models are not suitable for modelling this dynamic situation because they do not take into account the non-zero conditions at the transient moments. To address the shortfalls of the traditional approaches, a new class of shapers, the time varying leaky bucket shaper class, has been introduced and characterised by network calculus. To our knowledge, this is the first model that takes into account non-zero conditions at the transient time. This innovative result forms the basis of Renegotiable VBR Service (RVBR). The application of our RVBR mathematical model to the initial problem of supporting the applications' QoS requirements while efficiently allocating the network resources results in simple, efficient algorithms. Through simulation, we first compare RVBR service versus VBR service and versus renegotiable CBR service. We show that RVBR service provides significant advantages in terms of resource costs and resource utilisation. Then, we illustrate that when the service assumes zero conditions at the transient time, the source could potentially experience losses in the case of policing because of the mismatch between the assumed bucket and buffer level and the policed bucket and buffer level. As an example of RVBR service usage, we describe the simulation of RVBR service in a scenario where a sender transmits a MPEG2 video over a network using RSVP reservation protocol with Controlled-Load service. We also describe the implementation design of a Video on Demand application, which is the first example of an RVBR-enabled application. The simulation and experimentation results lead us to believe that RVBR service provides an adequate service (in terms of QoS guaranteed and of efficient resource allocation) to sources with pre-recorded or classified traffic

Application Requested IP over ATM (Arequipa) and its use in the Web

: When using the Web over the TCP/IP protocol suite of the Internet, there is (yet) no possibility to guarantee bandwidth or delay for the transmission of a document. For the multimedia documents of the Web, transmission with guaranteed quality of service (QoS) is however very desirable. ATM networks which are being deployed now are one means of solving this problem. They offer high bandwidths and QoS negotiation at connection establishment. Current implementations of IP over ATM do not pass these advantages of the underlying network to the application level. Assuming that standard solutions involving RSVP [5] and NHRP [8] will not soon be available, we present a service built on a dual stack (IP & ATM) approach which allows to transport IP streams over application requested ATM connections. We show how this service can be used to offer guaranteed QoS to Web users on ATM while preserving compatibility with users which can not benefit of ATM connections. Finally we show how this solutio..

ATM FORUM: Technical Working Group

This contribution is for information only. It provides an overview of Application REQUested IP over Atm ( AREQUIPA). Arequipa is an extension to the classical model of IP over ATM developed at EPFL. Arequipa allows applications running on an ATM attached machine to request dedicated ATM connections for IP data flows. For example, each TCP connection can be run on a dedicated ATM connection with the QoS necessary for that connection