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Communications and Networks, Journal of

Issue 2 • Date June 2000

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Displaying Results 1 - 18 of 18
  • A low cost approximation for a controlled load service in a bridged/switched LAN environment

    Publication Year: 2000 , Page(s): 103 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (463 KB)  

    This paper reports the design and the implementation results of a Controlled Load service in a bridged/switched Local Area Network (LAN). In contrast to other approaches, the service was built based on traffic aggregation and simple two level Static Priority scheduling within LAN switches. All complex control functions such as the per-flow packet classification, policing and traffic reshaping are only performed within end-nodes (hosts or routers) of the LAN. Admission Control is used to restrict the access to the new service. Measurement results received in a bridged test network exhibit low average end-to-end delay characteristics and no packet loss despite: 1) the simplicity of the traffic control implemented in our LAN switches, 2) a worst-case network load, and 3) the use of long range dependent data sources within the experiments. View full abstract»

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  • Performance comparison of layer 3 switches in cases of flow- and topology-driven connection setup

    Publication Year: 2000 , Page(s): 118 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (366 KB)  

    The layer 3 switch enables us to transmit IP datagrams fast using the cut-through technique. There are mainly two cases in establishing connections; one is the flow-driven case and the other is the topology-driven one. In this paper, we analyze the cut-through rate, the datagram waiting time and the mis-order rate as performance measure of both cases and compare these performances. In the analysis, by using interrupted Bernoulli process (IBP), we model the arrival process of IP flow and IP datagram from each source. Furthermore, we investigate impacts of the arrival rate and the average IP flow length on the performance. View full abstract»

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  • A quantitative study of differentiated services for the Internet

    Publication Year: 2000 , Page(s): 127 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The Differentiated Services architecture provides router mechanisms for aggregate traffic, and edge mechanisms for individual flows, that together can be used to build services with varying delay and loss behaviors. In this paper, we compare the loss and delay behaviors that can be provided using the services based on combinations of two router mechanisms, threshold dropping and priority scheduling and two packet marking mechanisms, edge-discarding and edge-marking. In the first part of our work, we compare the delay and loss behaviors of the two router mechanisms coupled with edge-discarding for a wide range of traffic arrivals. We observe that priority scheduling provides lower expected delays to preferred traffic than threshold dropping. In addition, we find that a considerable additional link bandwidth is needed with threshold dropping to provide same delay behavior as priority scheduling. We further observe little difference in the loss incurred by preferred traffic under both router mechanisms, except when sources are extremely bursty, in which case threshold dropping performs better. In the second part of our work, we examine the throughput of a TCP connection that uses a service built upon threshold dropping and edge-marking. Our analysis shows that a significant improvement in throughput can be achieved. However, we find that in order to fully achieve the benefit of such a packet marking, the TCP window must take the edge-marking mechanism into consideration. View full abstract»

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  • On managing traffic over virtual private network links

    Publication Year: 2000 , Page(s): 138 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A Virtual Private Network (VPN) provides corporate networking between geographically dispersed company sites. VPN sites consist of Local Area Networks (LANs) interconnected over a public network infrastructure, through virtual links. The goal of this work is to develop a control model able to manage traffic on these links. By maximizing bandwidth utilization on each link, an optimum balance for the allocation of bandwidth on the entire VPN can be found. The proposed model is called hierarchical bandwidth manager and is implemented in each LAN of the VPN. It is also able to cope with best-effort and guaranteed flows so that bandwidth left unused by guaranteed flows is dynamically distributed among best-effort ones. In each LAN, a tree representation is used to share the capacity of each virtual link between multiple flows in a hierarchical and distributed manner. Each node in the tree respects an inter-node bandwidth share protocol and/or is regulated through an intra-host regulation mechanism. This latter is implemented through a new technique which we call the fair shaper. An implementation of this technique in a Solaris 2.5 operating system and results of the implementation of the inter-node bandwidth share protocol in the ns network simulator are also described in this paper. View full abstract»

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  • Packet management techniques for measurement based end-to-end admission control in IP networks

    Publication Year: 2000 , Page(s): 147 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB)  

    End-to-end Measurement Based connection Admission Control (EMBAC) mechanisms have been proposed to support real-time flows quality of service requirements over a Differentiated Services Internet architecture. The EMBAC basic idea is to decentralize the admission control decision, by requiring each individual user to probe the network path during flow setup, and by basing the accept/reject decision on the probing traffic statistics measured at the destination. In conformance with the differentiated services framework, routers are oblivious to individual flows and only need to serve data packets with a higher priority than probing traffic. In this paper, we build upon the observation that some form of congestion control of the probing packets queue at each router is a key factor to provide performance effective EMBAC operation. The original contribution of the paper is twofold. First, we provide a thorough investigation, by means of both approximate analytical modeling and extensive simulation, of an EMBAC scheme (denoted in the following EMBAC-PD), in which probing queues congestion control is enforced by means of a probing packet expiration deadline at each router. Second, by means of extensive performance evaluation, we show that EMBAC-PD can provide strict QoS guarantees even in the presence of very light probing overhead (few probing packets per flow setup). Most interesting, EMBAC-PD does not necessarily require long probing phases to accurately estimate the network load subject to statistical fluctuations, but can provide effective operation even in the presence of extremely short probing phase duration (e.g., few hundreds of ms, acceptable for practical applications). View full abstract»

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  • BGRP: Sink-tree-based aggregation for inter-domain reservations

    Publication Year: 2000 , Page(s): 157 - 167
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB)  

    Resource reservation must operate in an efficient and scalable fashion, to accommodate the rapid growth of the Internet. In this paper, we describe a distributed architecture for inter-domain aggregated resource reservation for unicast traffic. We also present an associated protocol, called the Border Gateway Reservation Protocol (BGRP), that scales well, in terms of message processing load, state storage and bandwidth. Each stub or transit domain may use its own intra-domain resource reservation protocol. BGRP builds a sink tree for each of the stub domains. Each sink tree aggregates bandwidth reservations from all data sources in the network. Since backbone routers maintain only the sink tree information, the total number of reservations at each router scales linearly with the number of Internet domains N. (Even aggregated versions of the current protocol RSVP have a reservation count that can grow like O(N2).) BGRP maintains these aggregated reservations using “soft state.” To further reduce the protocol message traffic, routers may reserve bandwidth beyond the current load, so that some sources can join or leave the tree without sending messages all the way to the tree root. BGRP relies on Differentiated Services for data forwarding, hence the number of packet classifier entries is extremely small. View full abstract»

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  • QDMR: An efficient QoS dependent multicast routing algorithm

    Publication Year: 2000 , Page(s): 168 - 176
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    Many distributed real-time applications, such as audio-and video-conferencing and collaborative systems, require multicast support from the underlying network. Multicasting involves the delivery of messages over a tree rooted at the sender and whose paths lead to the various receivers. A major objective of the routing protocol is to build a tree with minimum cost. Finding such a tree is known to be computationally expensive, and many heuristics have been proposed to efficiently find near-optimal trees. Moreover, some heuristics exist to efficiently find multicast trees that are of low cost and satisfy Quality-of-Service (QoS) (e.g., delay) delivery constraints required by real-time applications. However, these heuristics are not fast enough for large-scale networks. In this paper, we present a fast algorithm, called QDMR, for generating delay-constrained low-cost multicast routing trees. A salient feature of QDMR is that it dynamically adjusts its low-cost tree construction policy based on how far the current on-tree node is from violating the QoS delay bound. This QoS dependent (adaptive) tree construction, together with the capability of merging least-delay paths into the low-cost tree in case of stringent delay requirements, lead to the following properties: 1) QDMR guarantees that a feasible multicast tree (that satisfies the requested delay) will be found if such tree exists; 2) this delay-bounded multicast tree is very rapidly generated; and 3) the tree has low cost. Through analysis and extensive simulations, we confirm the premise of QDMR by comparing it to many existing multicast algorithms. View full abstract»

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  • Measurement and interpretation of Internet packet loss

    Publication Year: 2000 , Page(s): 93 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB)  

    We analyze a month of Internet packet loss statistics for speech transmission using three different sets of client/server host pairs. Our results exhibit packet loss that is highly bursty, with the majority of individual losses occurring in a relatively small number of bursts. We find that loss exhibits dependence in most cases, but is not always well-modeled as dependent. We introduce an analytical technique for measuring loss dependency. We also consider the asymmetry of round-trip packet loss, and find that most loss on a round-trip path occurs in either one direction or the other. Thus, we provide a normalized metric for measuring loss asymmetry and apply it to our measurements. Finally, we discuss the implications of our study for the next generation of real-time voice services in the Internet. View full abstract»

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  • [Advertisement]

    Publication Year: 2000 , Page(s): 1
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  • Call for papers

    Publication Year: 2000 , Page(s): 1
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  • Call for papers

    Publication Year: 2000 , Page(s): 1
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  • Call for papers

    Publication Year: 2000 , Page(s): 1
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  • Journal of Communications and Networks Copyright transfer form

    Publication Year: 2000 , Page(s): 1
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  • [Front cover]

    Publication Year: 2000 , Page(s): c1
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  • [Back cover]

    Publication Year: 2000 , Page(s): c4
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  • Special issue on QoS in IP networks

    Publication Year: 2000 , Page(s): 89 - 92
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  • Journal of Communications and Networks (JCN) - back inside cover

    Publication Year: 2000 , Page(s): c3
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  • Journal of Communications and Networks (JCN) - back inside cover

    Publication Year: 2000 , Page(s): c2
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Aims & Scope

The Journal of Communications and Networks is published six times per year, and is committed to publishing high-quality papers that advance the state-of-the-art and practical applications of communications and information networks.

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Editor-in-Chief
H. Vincent Poor
Princeton University