Technion –Israel Institute of Technology

1. Technion –Israel Institute of Technology Computer Networks Laboratory & Digital laboratory Real Time Ethernet Semester Winter 2001 Students: Shay Auster & Hagit Chen Supervisor: Vitali Sokhin

2. RTE - Preview • An Ethernet protocol for Real-Time. • Analytic analisys of estimated performance. • Design an adiqute simulation. • Run various scenarios in simulation. • Conclusions.

3. Abstract • Real Time Streaming requires a bound on the time of which a packet is created until it reaches its destination. • IEEE 802.3u protocol does not support this requirment. • Hence, a Real Time Ethernet protocol needs to be defined.

4. RTE Protocol - Overview • Combine Ethernet and RTE transmisions on the same network. • On the same Lan – All RTE stations support the same application. • In order to coordinate transmisions between RTE stations – A mechanism to serializes transmisions.

5. head station 1 tail head station 2 tail head station 3 tail • Serializations of RTE transmitsions: • Head and Tail are required for the Handshaking - a mechanism which serealizes RTE transmisions.

6. Head: Clean channel for RT transmisions. Notify all other RT stations on RTE transmision status. Tail: Notify all other RT stations on RTE transmisions status. head standard ethernet frame tail RTE frame Ethernet frame bounded between a head and a tail

7. Overview cont. • Two possible situations in channel: • RTE transmision in channel – A new RTE station join the end of the chain. • No RTE transmision – The RTE station generates a new chain. • A RTE chain transmision in channel: • RTE station interupt at the end of the chain – no handshaking at 1st time. • Part of chain - handshaking from next time.

8. Final Results&Analysis

9. Ethernet – always transmits • Basic Ethernet simulation. • Stations always have packets to transmit.

10. Ethernet – always transmits • Ethernet simulation results are used as a reference in analysing RTE simulation results.

11. RTE – Always transmits • Ethernet – always transmit. • RTE – According to protocol.

12. RTE – always transmits • A Single RTE Station • Various number of Ethernet stations

13. RTE – always transmits • Three RTE Station • Various number of Ethernet stations

14. RTE – always transmits • Five RTE Station • Various number of Ethernet stations

15. Ethernet – The poissonic case • Poissonic arrival of packets to stations. • The interval between arrival of packets is exponential distributed  poissonic arrival of packets. • For exponential probability function we used an inverse distribution function.

16. Ethernet – poissonic case • Ethernet packets arrival rate is poissonic. • t =1000uSec ; mue =1

17. Ethernet – poissonic case • Ethernet packets arrival rate is poissonic. • t =500uSec ; differnet mue (0.5/1/2)

18. Ethernet – poissonic case • Ethernet packets arrival rate is poissonic. • Different t (500/1000/2000uSec) ; mue = 1

19. RTE – The poissonic case • Ethernet – Poissonic arrival of packets to stations. • RTE – According to protocol.

20. RTE – poissonic case • Ethernet packets arrival rate is poissonic. • A single RTE station. • t =1000uSec ; mue =1

21. RTE – poissonic case • Ethernet packets arrival rate is poissonic. • Three RTE stations. • t =1000uSec ; mue =1

22. RTE – poissonic case • Ethernet packets arrival rate is poissonic. • Five RTE stations. • t =1000uSec ; mue =1

23. RTE – poissonic case • Ethernet packets arrival rate is poissonic. • Different RTE stations. • t =1000uSec ; mue =1

24. Ethernet – The On/Off case • On – Always transmits. • Off – Never transmits. • The on/off intervals are exponentily distributed.

25. Ethernet – On/Off case • 64 Bytes packet. • Different On/Off data.

26. Ethernet – On/Off case • 256 Bytes packet. • Different On/Off data.

27. Ethernet – On/Off case • 1024 Bytes packet. • Different On/Off data.

28. RTE – The On/Off case • Ethernet - • On – Always transmits. • Off – Never transmits. • RTE – According to protocol.

29. RTE – On/Off case • 1024 bytes Ethernet packets. • A Single RTE station. • Different On/Off data.

30. RTE – On/Off case • 1024 bytes Ethernet packets. • Three RTE stations. • Different On/Off data.

31. RTE – On/Off case • 1024 bytes Ethernet packets. • Five RTE stations. • Different On/Off data.

32. Ethernet – Stations Wait Time • Ethernet – Allways transmit. • No RTE. • Wait time increases with packet size.

33. RTE – Stations Wait Time • Ethernet – Allways transmit. • One RTE station. • Wait time increases with packet size. • Wait time increases with number of RTE stations.

34. RTE – Stations Wait Time • Ethernet – Allways transmit. • Three RTE stations. • Wait time increases with packet size. • Wait time increases with number of RTE stations.

35. RTE – Stations Wait Time • Ethernet – Allways transmit. • Five RTE stations. • Wait time increases with packet size. • Wait time increases with number of RTE stations.

36. RTE - Jitter • Ethernet – Allways transmit. • Various number of RTE stations. • Jitter increases with packet size & number of RTE stations.

37. Time to genrate RTE chain • Ethernet – Allways transmit. • Various number of RTE stations. • Chain time increases with number of RTE stations.

38. Application example • Ethernet – Allways transmit. • Various number of RTE stations. • Application sampeling rate 1.5Mbps.

39. Conclusions • RTE stations uses a part of the Ethernet channel  Ethernet stations Efficiency decreases. • The total chanel efficiency increases. • For Ethernet – allways transmit & on/off arrival times we get an immediate reduce of efficiency. • For poisonic arrival of packets we don’t get an immediate reduce of efficiency.

40. Conclusions • For each arrival pattern – channel efficiency converges to the allways transmits results (for sufficient number of stations). • More stations (regular/RTE)  Larger wait time. • Bigger packets  Larger wait time. Larger Jitter.