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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. - PowerPoint PPT Presentation
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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.