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

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

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.

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.

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

RTE frame  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. Ethernet frame bounded between a head and a tail tailstandard ethernet framehead

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 1 st time.  Part of chain - handshaking from next time.

Final Results & Analysis

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

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

RTE – Always transmits  Ethernet – always transmit.  RTE – According to protocol.

RTE – always transmits  A Single RTE Station  Various number of Ethernet stations

RTE – always transmits  Three RTE Station  Various number of Ethernet stations

RTE – always transmits  Five RTE Station  Various number of Ethernet stations

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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.