DBS: Distributed Benchmark System

Performance Evaluation on ATM and Router Network

• System Structure

  

• Data sheet

    CPU                SUN SPARCstation10
    OS                 SunOS 4.1.3
    ATM Swintch        NEC ATOMIS 5
    ATM Card           SBA-200
    Router             NEC C&C-NET IP 45/650
    AAL Type           AAL5
    MTU                9188octet
    TCP Buffer Size    52428byte
    Message Size       8196byte
    Start Time         HOST1->(Router)->HOST3: 0.00s
                       HOST2->(Router)->HOST3: 2.00s
    number of send     HOST1->(Router)->HOST3: 2000
                       HOST2->(Router)->HOST3:  500
    

• DBS Command File

• Sequence Number(Application Level)

  

• Throughput(Application Level)

  

  When there is one data stream, the throughput is about 23Mbps. The bottleneck is the performace of the router. If you have not seen this graph, you may think that if there exist two data streams, each throughput must become about 11.5Mbps or greater and the sum of the throughput must be between 23Mbps to 32Mbps. However, it is WRONG! Data segments are transfered intermittently and each throughputs are terrible bad. The reason is thought that the router is overloaded. TCP must avoid congestion but TCP congestion avoidance mechanism functioning at the IP packet level dose not work well toward the congestion occured by the ATM cell level. ATM used by UBR mode is unfamiliar with TCP.