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230 Terminals/ Terminal Adapters •TV • N-ISDN • PC file transfer • Multimedia Traffic Generators & Analysers The main areas of interest for this SIG are: - Definition and evaluation of multiplexing schemes - Evaluation of mechanisms for the support of ABR - Usage and Network Parameter Control (UPC/NPC) and traffic shaping - Fast Resource Management (FRM, or ABT) - ATM Performance. The participating projects are BAF, BRAVE, COMBINE, EXPLOIT, LACE and TRIBUNE. The SIG produces a Baseline document on Traffic Control and ATM Performance [2] consisting of Part A: Theoretical results, and Part B: Experimental results, giving an overview of results obtained within the projects. Here we will only give an indication of topics dealt with in these project related to the different ATM layer bearer capabilities, without the intention of giving an exhaustive description of all aspects covered. EXPLOIT – Exploitation of an ATM Technology Testbed for Broadband Experiments and Applications The EXPLOIT Testbed has been developed within two RACE projects with more than 30 partners (operators, industries and universities) involved. It is located in Basel and comprises: - 4 ATM switches with various internal architecture - Terminal equipment: Multimedia, TVs, PCs, N-ISDN - Broadband signalling - Interworking Units and Mappers - Traffic generators and analysers. The EXPLOIT testbed may be configured in a flexible way to create different complete ATM networks for traffic investiga- Switching network UPC & CAC IWU's • 2 Mbit/s •FR Mappers • 2 Mbit/s • 34 Mbit/s Connections • ATM Pilot Network • MEGACOM- Swissnet • Satellite tions. The ATM switches have small buffers and are used for studying the performance of preventive traffic control functions. A lot of experiments with different UPC algorithms have been carried out with main focus on combined peak cell rate and sustainable cell rate policing using the implemented dual leaky bucket mechanism. The performance of Connection Admission Control (CAC) algorithms have also been evaluated by multiplexing both homogeneous and heterogeneous traffic mixes with various on/off sources from traffic generators. The consistency and the robustness of the co-operation between the UPC and the CAC are being addressed. Thus, the statistical multiplexing gain obtainable based on the PCR and the SCR traffic parameters in a network with small buffers is evaluated. The small buffers can absorb only cell level congestion, hence the resource allocation scheme has to take care of the burst level statistics to prevent excessive cell losses. Furthermore, experiments are being carried out on resource management and performance assessment of end-to-end delays and cell losses through networks, including connections through the PEAN. Both artificial traffic from generators as well as real traffic applications are used in the experiments. BRAVE – Broadband Access Verification Experiments In the BRAVE project, multiplexing schemes based on FRM and ABR are investigated. The BRAVE platform for carrying out experiments to verify the chosen solutions consists of three broadband islands: - one located in Milan and hosted by Italtel - one hosted by Siemens (to be located in Berlin?) - one located in Turin and hosted by CSELT. These islands are interconnected through the Pan European ATM Network (PEAN). The ABR protocol will be tested on this platform using an ATM PC connected to a Service Multiplexer (SM) and ATM Concentrator on the Siemens island, connected across the PEAN to Milan island European ATM Pilot Network Figure 1 The EXPLOIT Testbed Figure 2 The BRAVE Platform ABR FRM Turin island FRM Siemens island ABR
another SM with LANs at the Italtel island. A rate based ABR version is implemented in the terminal, the SM and the ATM Concentrator. Large buffers are necessary to cope with ABR traffic and will be implemented in the ATM Concentrator. The differences between how ATM traffic is handled when using ABR or VBR bearer capability will be highlighted in the experiments. Assessment of the multiplexing gain and the effects of ABR parameter choices on ABR performance will be given. Furthermore, experiments will be performed with an FRM mechanism implemented in the Italtel and CSELT islands in the BRAVE platform interconnected via the PEAN. The efficiency of FRM schemes with delayed transmission depends heavily on the relation between the response time to reserve resources and the holding times of the resources necessary to transfer the information. The response time depends on the round-trip delay of the connection together with processing time in the FRM handling units. However, the holding times are determined by the traffic profile generated by the upper layers. In BRAVE the efficiency of FRM schemes will be studied by considering real traffic generated when running applications like file transfer and remote connections. In FRM schemes there is a probability that the request from a user for allocation of resources will be rejected by the network due to lack of resources, and reattempts will be necessary after a certain delay. The burst level blocking probability becomes a QoS parameter in this scheme and will be measured when running real applications. LACE – Local Applied Customer Environment for integrated communications One way of supporting bursty data traffic is to base it on a best effort service. However, to be effective a loss-free operation should be ensured to avoid excessive retransmissions. Backpressure policies to achieve this are under study in the LACE project. A hop-by-hop flow control will stop and restart the traffic per connection depending on the loading in the switch buffers. The mechanism will throttle the best effort traffic when congestion occurs to avoid cell losses in the network, and make it possible for this kind of traffic to grab as much as possible from the non-reserved and the unused resources. The efficiency in adapting to changing link load, the fairness independent of the location of sources, and the scalability with respect to number of nodes and distances are being studied. References 1 ITU. Traffic control and congestion control in B-ISDN. Paris, 1995. (ITU-T Recommendation I.371, Frozen Issue.) 2 SIG on Traffic control and ATM performance, Baseline Document, Issue 2. 14 March 1995. 231
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Contents Feature Guest editorial, A
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4 N sources 1 The delay along the p
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14 Table 2 Survey of some distribut
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16 0 Local calls mean: 27 sec. Std.
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18 Frame 5 Equilibrium calculations
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20 j k λ ij µji λ ik µ ki λ ir
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22 14 Disturbed and shaped traffic
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26 n * ooo---o A * M, V stream is n
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28 A-subscr. Network B-subscr. λ(
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30 Frame 6 Basic queuing model From
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32 Traffic sources (N) ⇒ III - -
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34 Since Gw (t) is the survivor fun
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38 Figure 38 Mixed international da
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40 3 Gaaren, S. LAN interconnection
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42 Solution of some problems in the
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44 Table 3 a. The “Loss” (in
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46 Table 6. (x = 3). a n 0.0 0.1 0.
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48 Telephone Systems” (published
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50 The life and work of Conny Palm
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52 mind that the seventies were bef
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54 of random traffic it is tacitly
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56 Architectures for the modelling
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58 QoS user Service catagories user
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60 (N)-service-user (N)-service-pro
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62 ACSE Presentation layer Session
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64 Traffic source 1 Traffic source
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oth the traditional ack-based and t
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80 Similarly as for Poisson-traffic
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82 throughput 1 Introduction Commun
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84 processor load Figure 4 its cust
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86 load control mechanisms. It is u
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88 ers to use the same facility at
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90 CE CE Figure 3 IRIM with cluster
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92 and one mini IRSU and one normal
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Table 4 Combined signalling and pac
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96 mission cost of large capacities
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102 According to our plans reroutin
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104 Based on the experiences with t
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user access device 106 sound/speech
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108 overs for mobile stations that
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110 radio interface tion inside a b
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Figure 9 One way of defining space
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114 frequency code here. However, t
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116 class 1 class 2 class 3 [1,1,1]
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1.00E-00 1.00E-01 1.00E-02 case I c
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400 300 200 100 25 25 20 10 120 (a)
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Erlang Erlang Erlang 122 7 6 5 4 3
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124 Table 6 Call holding times (in
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Registered number of calls Register
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Table 9 Number of call attempts, su
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130 LAN Interconnection Traffic Mea
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132 gering table could be employed
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134 OSI name/layer 7) Application 6
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136 kbit/s 4000 3000 2000 1000 0 kb
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Number of type 2 connections 140 Fe
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148 Background Traffic Test Traffic
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150 ATM cell header 2.1.1 Measuring
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156 Sparc2 (SunOS 4.1.1) or Sparc10
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158 Segment size [byte] 8192 6144 4
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160 Throughput [Mbit/s] Throughput
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162 Segment size [byte] Unacknowled
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164 Throughput [Mbit/s] 30 20 4 kby
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166 Throughput [Mbit/s] Throughput
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168 TEL A TEL B Satellitedish Swiss
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170 Cell Discard Ratio Cell Discard
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172 Number of Type 2 Sources Number
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178 Transp. Network LLC MAC PHY Tra
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