Current Test Conclusions (April 1997)

The progress with benchmarking the network and host computers is summarised in the sections below:

10 Mbps Performance

The local area network is capable of forwarding a simplex data stream (unicast or multicast) of 10 Mbps without introducing any bottleneck to achieve a 100% utilisation of the network. The performance reduces due to collisions when end systems are sending data in both directions using a shared medium (10 or 100 Mbps hub). The switch and the hub do not introduce any bottleneck to the network.

100 Mbps Performance

The 100 Mbps interface card of the Ultra workstation limits the transmission rate to about 68 Mbps (at the transport layer). The switch and the hub do not introduce any bottleneck to the network. The performance of the network significantly reduces when packets travel through our router due to unexplained overhead. This needs further study, and will be investigated when we receive the delivery PCs.

100/10 Mbps Performance

The speed and the transmission capability mismatch between different end systems results in significant performance reduction for the systems with less capability. These results may be significant when designing interactive CAL applications. The high capacity video server can in some circumstances capture the network capacity while transmitting data to a number of stations which request data. This may result in freezing of the backward traffic (e.g. a request from another client).

Status Summary

The following equipment has been installed and configured:

  1. SUN Test hosts at ERG
  2. PC development computer at ERG
  3. PC development computer at FH
  4. Network connection ERG / AUCC VCS via campus network
  5. CISCO Ethernet Switch (100/10)
  6. 3COM Ethernet Hub (100)
  7. CISCO Router (100/10)
  8. Delivery PCs in Classroom used by Medi-CAL
  9. Network connection AUCC VCS / ERG via campus network (10 Mbps / FDDI)
  10. Network connection AUCC VCS / ERG via dedicated link (10 Mbps)
  11. Network connection AUCC VCS / FH via ATM network

The current software development is summarised below:

  1. Definition of Interface between CAL application & Network Transport Protocol - Completed
  2. Delay & Throughput Measurement Tools - Developed & Tested
  3. Porting Tools to PC Delivery Computers & Benchmark
  4. Simplex Delivery of Video from VCS to Delivery PC - Planned for 2Q98

Summary of Future work

The end-to-end performance between two systems with 100 Mbps interfaces needs to be tested and tests will be arranged after arrival (on loan) of 2 of the delivery PCs from the computer centre.

The results shown in this report only provide initial measurements, and they will be further analysed, and accurate results will later be reported.

The wide area performance between VCS and the delivery PCs needs to be analysed, both on the dedicated VCS link to ERG and via the ATM network to Forester Hill.

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