Technion –Israel Institute of Technology

Computer Networks Laboratory & Digital laboratory

Real Time EthernetSemester 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 1st 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.

Channel Efficiency vs. Number Of Stations NoRte ; AllWays Transmits

0

10

20

30

40

50

60

70

80

90

100

1 2 4 8 16 32 64 128 256

Number Of Stations

Eff

icie

ncy

(%

) Packet Size 1024

Packet Size 512

Packet Size 256

Packet Size 128

Packet Size 64

RTE – Always transmits

Ethernet – always transmit.

RTE – According to protocol.

RTE – always transmits

A Single RTE Station Various number of Ethernet stations

Efficiency vs. Number Of Stations 1Rte ; Allways Transmits

0

10

20

30

40

50

60

70

80

90

1 2 4 8 16 32 64 128 256

Number Of Stations

Eff

icie

ncy (

%) Packet Size 1024

Packet Size 512

Packet Size 256

Packet Size 128

Packet Size 64

RTE – always transmits

Three RTE Station Various number of Ethernet stations

Efficiency vs. Number Of Stations 3RTE ; Allways Trnsmits

0

10

20

30

40

50

60

1 2 4 8 16 32 64 128 256

Number Of Stations

Eff

icie

ncy (

%)

Packet Size 1024

Packet Size 512

Packet Size 256

Packet Size 128

Packet Size 64

RTE – always transmits

Five RTE Station Various number of Ethernet stations

Efficiency vs. Number Of Stations5RTE ; Allways Transmits

0

5

10

15

20

25

30

1 2 4 8 16 32 64 128 256

Number Of Stations

Eff

icie

nc

y (

%) Packet Size 1024

Packet Size 512

Packet Size 256

Packet Size 128

Packet Size 64

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

Channel Efficiency vs. Number Of Ethernet Stations (poissonic arrival of Ethernet packets, differenet packet size,

t=1000uSec, mue=1, no RTE stations)

0

10

20

30

40

50

60

70

80

90

100

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

NoRte 1024

NoRte 512

NoRte 256

NoRte 128

NoRte 64

Ethernet – poissonic case

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

Channel Efficiency vs. Number Of Stations (poissonic arrival of Ethernet packets, Packets Size=1024 Bytes,

t=500, different mue)

0

10

20

30

40

50

60

70

80

90

100

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

an

ne

l Eff

icie

nc

y (

%)

1024 500 0.5

1024 500 1

1024 500 2

Ethernet – poissonic case

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

Channel Efficiency vs. Number Of Ethernet Stations (poissonic arrival of Ethernet packets, packet size of 1024 Bytes,

differnet t, mue=1, no RTE stations)

0102030405060708090

100

1 2 4 8 16 32 64 128 256

Number Of Ethernet Stations

Ch

an

ne

l Eff

icie

nc

y (

%)

1024 500 1

1024 1000 1

1024 2000 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

Channel Efficiency vs. Number Of Ethernet Stations (1 RTE Station, poissonic arrival of Ethernet Packets,

t=1000uSec, mue=1)

0

10

20

30

40

50

60

70

80

1 2 4 8 16 32 64 128 256

Number Of Ethernet Stations

Ch

ann

el E

ffic

ien

cy (

%)

1rte 1024

1rte 512

1rte 256

1rte 128

1rte 64

RTE – poissonic case

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

Channel Efficiency vs. Number Of Stations (3 RTE Stations, poissonic arrival of Ethernet packets,

t=1000uSec, mue=1)

0

10

20

30

40

50

60

1 2 4 8 16 32 64 128 256

Number Of Ethernet Stations

Ch

an

ne

l Eff

icie

nc

y (

%)

3rte 1024

3rte 512

3rte 256

3rte 128

3rte 64

RTE – poissonic case

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

Channel Efficiency vs. Num of Ethernet Stations (5RTE Stations, poissonic arrival of Ethernet packets, t=1000uSec,

mue=1)

0

5

10

15

20

25

30

1 2 4 8 16 32 64 128 256

Number Of Ethernet Stations

Eth

ern

et C

han

nel

Eff

icie

ncy

(%

)

5rte 1024

5rte 512

5rte 256

5rte 128

5rte 64

RTE – poissonic case

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

Channel Efficiency vs. Number Of Ethernet Stations (differenet RTE Stations, poissonic arrival of Ethernet packets, t=1000uSec,

mue=1)

0

10

20

30

40

50

60

70

1 2 4 8 16 32 64 128 256

Number Of Ethernet Stations

Cha

nnel

Eff

icie

ncy

(%)

NoRte 256

1Rte 256

3Rte 256

5Rte 256

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.

Channel Efficiency vs. Number Of Stations (Packet Size=64Bytes, Poisson on/off, t=1000uSec, No RTE stations)

0

5

10

15

20

25

30

35

40

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1 offMue=1

onMue=1 offMue=2

onMue=2 offMue=1

Ethernet – On/Off case

256 Bytes packet. Different On/Off data.

Channel Efficiency vs. Number Of Stations (Packet Size=256Bytes, Poisson on/off, t=1000uec, No RTE stations)

0

10

20

30

40

50

60

70

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1, offMue=1

onMue=1, offMue=2

onMue=2, offMue=1

Ethernet – On/Off case

1024 Bytes packet. Different On/Off data.

Channel Efficiency vs. Number Of Stations (Packet Size=1024Bytes, Poisson on/off, t=1000uSec, No RTE stations)

0

10

20

30

40

50

60

70

80

90

100

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1, offMue=1

onMue=1, offMue=2

onMue=2, offMue=1

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.

Channel Efficiency vs. Number Of Stations (Packet Size=1024Bytes, Poisson on/off, t=1000uSec, 1 RTE stations)

0

10

20

30

40

50

60

70

80

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1, offMue=1

onMue=1, offMue=2

onMue=2, offMue=1

RTE – On/Off case

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

Channel Efficiency vs. Number Of Stations (Packet Size-1024Bytes, Poisson on/off, t=1000uSec, 3 RTE stations)

0

10

20

30

40

50

60

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1, offMue=1

onMue=1, offMue=2

onMue=2, offMue=1

RTE – On/Off case

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

Channel Efficiency vs. Number Of Stations (Packet Size=1024Bytes, Poisson on/off, t=1000uSec, 5 RTE stations)

0

5

10

15

20

25

30

1 2 4 8 16 32 64 128 256

Number Of Stations

Ch

ann

el E

ffic

ien

cy (

%)

onMue=1, offMue=1

onMue=1, offMue=2

onMue=2, offMue=1

Ethernet – Stations Wait Time

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

Average wait time vs. Num of Stations No RTE stations. Allways transmits.

0

5

10

15

20

25

30

1 2 4 8 16 32 64 128 256

Num of Stations

Wa

it t

ime

(m

illi S

ec

)

1024 Bytes

512 Bytes

256 Bytes

128 Bytes

64 Bytes

RTE – Stations Wait Time

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

Wait Time vs. Num of Stations1 RTE stations. Allways transmits.

0

5

10

15

20

25

30

35

1 2 4 8 16 32 64 128 256

Num of Stations

Wa

it T

ime

(m

illi s

ec

)

1024 Bytes

512 Bytes

256 Bytes

128 Bytes

64 Bytes

RTE – Stations Wait Time

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

Wait Time vs. Num of Stations 3 RTE. Allways Transmits

0

5

10

15

20

25

30

35

40

45

50

1 2 4 8 16 32 64 128 256

Num of Stations

Wa

it T

ime

(m

illi s

ec

)

1024 Bytes

512 Bytes

256 Bytes

128 Bytes

64 Bytes

RTE – Stations Wait Time

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

Wait Time vs. Num of Stations5 RTE. Allways Transmits

0

10

20

30

40

50

60

70

80

90

1 2 4 8 16 32 64 128 256

Num of Stations

Wa

it T

ime

(m

illi s

ec

)

1024 Bytes

512 Bytes

256 Bytes

128 Bytes

64 Bytes

RTE - Jitter

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

stations.

Jitter Time (nano sec) vs. Packet Size

0

10000

20000

30000

40000

50000

60000

64 128 256 512 1024

Packet Size

Jit

ter

(na

no

se

c)

1 RTE

3 RTE

5 RTE

Time to genrate RTE chain

Ethernet – Allways transmit. Various number of RTE stations. Chain time increases with number of RTE

stations.

Chain Time vs. Num of RTE Stations

0

2000000

4000000

6000000

8000000

10000000

12000000

1 3 5

Num Of RTE Stations

Ch

ain

Tim

e (n

ano

Sec

)

Application example

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

Channel Efficiency vs. Num of Stations RTE Rate = 1.5Mbps

0

10

20

30

40

50

60

70

80

90

100

1 2 4 8 16 32 64 128 256

Num of Stations

Ch

an

ne

l Eff

icie

nc

y (

%)

60 RTE

30 RTE

1 RTE

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.