Wyniki wyszukiwania - BazTech

1

Scheduling architectures for DiffServ networks with input queuing switches

Yang M., Selvaray H., Lu E., Wang J., Zheng S. Q., Jiang Y.

Electronics and Telecommunications Quarterly

|

2009

|

Vol. 55, No 1

9-30

EN

Due to its simplicity and scalability, the differentiated services (DiffServ) model is expected to be widely deployed across wired and wireless networks. Though DiffServ supporting scheduling algorithms for output-queuing (OQ) switches have been widely studied, there are few DiffServ scheduling algorithms for input-queuing (IQ) switches in the literaure. In this paper, we propose two DiffServ scheduling algorithms for DiffServ networks with IQ switches: the dynamic DiffServ scheduling (DDS) algorithm and the hierarchical DiffServ scheduling (HDS) algorithm. The basic idea of DDS and HDS is to schedule EF and AF traffic according to their minimum service rates with the reserved bandwidth and schedule AF and BE traffic fairly with the excess bandwidth. Both DDS and HDS find a maximal weight matching but in different ways. DDS employs a centralized scheduling scheme. HDS features a hierarchical scheduling scheme that consists of two levels of schedulers: the central scheduler and port schedulers. Using such a hierarchical scheme, the implementation complexity and the amount of information needs to be transmitted between input ports and the central scheduler for HDS are dramatically reduced compared with DDS. Through simulations, we show that both DDS and HDS provide minimum bandwidth guarantees for EF and AF traffic as well as fair bandwidth allocation for BE traffic. The delay and jitter performance of DDS is close to that of PQWRR, an existing DiffServ supporting scheduling algorithm for OQ switches. The tradeoff of the simpler implementation scheme of HDS is its slightly worse delay performance compared with DDS.

2

Comparative evaluation of distributed Bandwidth Broker

Żmudziński P., Piechowiak M.

Image Processing & Communications

|

2006

|

Vol. 11, no 1

59-69

EN

The Differentiated Services (DS) framework is one of the basic architectures that have been proposed for provision in the Internet. One of the most significant advantages of DS is ability to distinguish management plane of the network to provide the customer Quality of Service. A DS architecture proposed by IETF alone is not sufficient to address the end-to-end guaranties in a network layer but it does show great potential for scalability. To fulfill negotiated QoS services Bandwidth Broker - an additional management entity, has to be implemented. The main tasks of the Broker are: limiting the traffic volume carried through the managed domain and services nego-tiation on behalf of domain with customers and adjacent brokers. The authors concentrated on the concept of distributed Broker as a more scalable and efficient solution. The different bandwidth allocation scenarios are presented and compared with regard to signaling overhead, admission control delay and control complexity. The quota-based admission control algorithm has been briefly described and discussed. The new style of reservation has been proposed to decrease the amount of signaling traffic between core and edge routers. The example of its functioning has been given at the end of the presented paper.

3

Methods for evaluation packet delay distribution of flows using Expedited Forwarding PHB

Kaczmarek S., Narloch M.

Journal of Telecommunications and Information Technology

|

2004

|

nr 2

29-37

EN

The paper regards problem of providing statistical performance guarantees for real-time flows using Expedited Forwarding Per Hop Behavior (EF PHB) in IP Differentiated Services networks. Statistical approach to EF flows performance guarantees, based on calculation of probability that end-to-end packet delay is larger than certain value, allows larger network utilization than previously proposed deterministic approach. In the paper different methods of packet delay distribution evaluation are presented and compared. Considered cases comprise evaluation of delay distribution models for the core network and evaluation of end-to-end packet delay in the network consisted of edge node and chain of core nodes. Results obtained with aid of analytical models are compared with simulation results.

4

A concept of Differentiated Services architecture supporting military oriented Quality of Service

Kwiatkowski M.

Journal of Telecommunications and Information Technology

|

2003

|

nr 2

71-76

EN

This paper presents a concept of IP Differentiated Services (DiffServ) architecture in conjunction with bandwidth brokerage and policy based network management, all aimed at efficient and flexible provision of the military oriented Quality of Service (M-QoS) features in the Australian Defence (strategic) wide area network and its satellite trunk interconnections with the tactical domain. Typical DiffServ functions are analysed in the paper with regard to their roles in offering M-QoS. Some preliminary simulation results of applying these mechanisms to achieve traffic policing and differentiation for (UDP) video traffic streams, are also presented. Finally, the paper proposes the use of bandwidth brokerage in each DiffiServ domain to facilitate automatic Service Level Specification (SLS) arrangements with end-user applications, and policy based network management to support the flexible implementation of bandwidth brokerage.