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A Study Of Cyclone Technology

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Table of Content

• Overview

• Contributions

• The need for time-based resource management

• Cyclone technology - basic idea

• Description of a Cyclone network

• Clock synchronization

• Data movements

• Connection management

• Scheduling

• Adaptation layer

• Fault handling

• Performance

• Advantages and limitations

• Open issues

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• Current networking– event-based, on-demand resource allocation

– best effort performance

• New classes of traffic placing stringent requirements on the communications

• Time-based resource management in a synchronous manner

• End-to-end coordination among network components– no congestion, loss, jitter

– better utilization of bandwidth• one byte header

• reduced control messages

• reduced routing information

– well-suited network environment for traffic with stringent timing requirements

Overview

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Contributions

• Time-based networking technology– components

– protocols

– operations

– host interface

• Time-based resource management

• Alternate way of managing resources in networking– without requiring very accurate and highly synchronized clocks

– without consuming significant amount of bandwidth for handling timing variability

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Time-based Resource Management In Networking

l in k 1

lin k 2n o d e X

n o d eY

n o d e ZA B

C D

t1 t2

t3 t4

t5 t6

t7 t8

t9 t10

A

B

Data Loss

t1 t2

t3 t4

t5 t6

t7 t8

t9 t10

A

B

Data Loss Prevention

Delay and Jitter

A

B

t1 t2

t3 t4

t9 t10

t5 t6

t7 t8

t11 t12

Delay and Jitter Control

A

B

t1 t2

t3 t4

t9 t10

t5 t6

t7 t8

t11 t12

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Cyclone Technology - Basic Idea

tAtA+sA

tA+2sAtA+3sA

tA+isA

tA+(i-1)sA

tA+(i+1)sA

tBtB+sBtB+2sB

tB+(j-1)sB

tB+(j+1)sB

tB+jsB

. . .

. . .

tAtA+sA

tA+dtA+sA+d

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Data Movements - Basic

Incoming link Outgoing link

Slot buffer Pointer buffer

Free slot list

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Data Movements

controller

switch

host

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Types Of Traffic Supported

• Connection-oriented

• Scheduled traffic– data available at known time instant (temporal profile)

– resources reserved when establishing a connection

• On-demand traffic– source routing

– dynamic resource allocation

– possible loss of a chunk

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Description Of Cyclone Network

• Chunk

• Slot and slot time

• Time tag

• Period

• Fixed design parameters– the size of a chunk

– the duration of a period

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Chunk Types

• Three types - Control/Scheduled/On-demand

• Control chunk– multiple sub-chunks in a chunk

– connection request chunk

– confirm/reject/abort/terminate chunk

– pathfinder chunk

• Scheduled chunk– scheduled traffic data chunk

– scheduled traffic data acknowledgement/retransmission request chunk

• On-demand chunk– on-demand traffic data chunk

– on-demand traffic data acknowledgement/retransmission request chunk

marker checksum

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Multiple Sub-chunks In A Chunk

marker n subchunk paddingsubchunk checksum. . .

512 bytes

8 bit marker8 bit n is the number of subchunks contained;

maximum is (512-1-1-2)/bwhere b is the number of bytes in a subchunk (127)

b*n bit subchunks where b is the number of bits in a subchunkv bit padding where (v=(512-1-1-b*n-2)*8>=0)16 bit checksum

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Connection Request Chunk

8 bit marker160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)8 bit type of services64 bit start time64 bit end time16 bit s is the number of temporal descriptors in this chunk24*sbit temporal behaviorv bit padding where (v=(512-1-20-20-1-8-8-2-3*s-2)*8>=0)16 bit checksum

512 bytes

marker ToSsource destination paddingtemporalbehavior

checksumstart end s

8 bit marker160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)16 bit s is the number of temporal descriptors in this chunk24*sbit temporal behaviorv bit padding where (v=(512-1-20-20-2-3*s-2)*8>=0)16 bit checksum

512 bytes

marker source destination paddingtemporalbehavior

checksums

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Confirm/Reject/Abort/Terminate Chunk

8 bit marker160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)672 bit padding (127-1-20-20-2)*216 bit checksum

marker source destination padding checksum

127 bytes

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Pathfinder Chunk

8 bit marker160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)8 bit number of hops(h)*8 bit pointer into current hop position**8*h*2 bit list of outgoing and incoming link identifier pair at each hop*v bit padding where (v=(127-1-20-20-1-1-1*h*2-2)*8>=0)*16 bit checksum** recomputed at each hop on forward path**recomputed at each hop on forward and reverse paths

marker source destination list* checksum*hops* padding*

127 bytes

pointer**

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Scheduled Traffic Data and Acknowledgement/Retransmission Request Chunk

8 bit chunk marker8*d bit data (d bytes of data)v bit padding where (v=(512-1-1*d-2)*8>=0)16 bit checksum

datamarker checksumpadding

512 bytes

8 bit marker160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)16 bit slot sequence number for this connection656 bit padding (127-1-20-20-2-2)*816 bit checksum

marker source destination sequence padding checksum

127 bytes

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On-Demand Traffic Data And Acknowledgement/Retransmission Request Chunk

8 bit check marker8 bit number of hops8 bit index into current hop information8*h*2 bit list of outgoing and incoming link identifier pair at each hop160 bit source address160 bit destination address8*d bit data (d byte data)v bit padding where (v=(512-1-1-1-1*h*2-20-20-1*d-2)*8>=0)16 bit checksum** recomputed at each hop

marker list data padding checksum*

512 bytes

hop pointer* source destination

8 bit marker8 bit number of hops(h)8 bit index into current hop information*8*h*2 bit list of outgoing and incoming link identifier pair at each hop160 bit source address (128 bit address + 32 bit port)160 bit destination address (128 bit address + 32 bit port)8*d bit data containing acknowledgement/retransmit requestv bit padding where (v=(127-1-1-1-1*h*2-20-20-1*d-2)*8>=0)16 bit checksum** recomputed at each hop

marker source destinationlist checksum*hops padding

127 bytes

pointer* data

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Cyclone Network ModelNon-Cyclone

Network

Non-Cyclone Network

Tem poral Regulator

Cyclonode

controller

switch

Incoming link 1

Incoming link m

outgoing link 1

outgoing link m

Backup Incoming

link 1’

Backup Incoming link m’

Backup outgoing link 1’

Backup outgoing link m’

1’

m’

host

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Clock Synchronization

• Markers are sent to indicate the beginning and ending of a period

• A node obtains the clock information of upstream nodes

• A local clock rate is set to the average of incoming clock rates and its own rate

• A local clock phase is set considering clock phase information

Clock Adjustment At A Node With Four Incoming Links

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Connection Establishment/Termination

A

B

C

D

E6

12

5

7

4

3

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Time Relationship Of Scheduling

Timeline of incoming link

Timeline of outgoing link (same speed)

Timeline of outgoing link (slower)

Timeline of outgoing link (faster)

t1 t2

t3 t4

t3

t3

t4

t4

4231 tttt

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Single-Pass Scheduling Approach

0 1 2 3 4 5 6 7

22

23

24

25

0 1 2 3 4 5 6 7

22

23

24

25

26

0 1 2 3 4 5 6 7

22

23

24

25

26

21

27

28

Available slot list

(2, 3, 5, 6, 7)

(3, 6, 7)

(3)

(1, 3, 4, 5)

• First available slot column assignment

• Assignment before reusing the buffer space

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Double-Pass Scheduling Approach

0 1 2 3 4 5 6 7

21

22

23

24

25

26

27

0 1 2 3 4 5 6 7

28

21

22

23

24

25

26

27

Available slot list

(1, 2, 3, 4, 6)

(2, 3, 4)

0 1 2 3 4 5 6 7

28

21

22

23

24

25

26

27

Available slot list

(1, 2, 3, 4, 6)

(2, 3, 4)

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Double-Pass Scheduling Approach

0 1 2 3 4 5 6 7

21

22

23

24

25

26

27

0 1 2 3 4 5 6 7

28

21

22

23

24

25

26

27

Available slot list

(1, 2, 3, 4, 6)

(2, 3, 4)

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Adaptation Layer

• Receive information from an application and provide the appropriate information to a temporal regulator in the form acceptable to a Cyclone network

– Specify temporal profile for a scheduled traffic

– Provide scheduled data chunks according to the temporal profile specified

– Detect bit-errors

– Initiate appropriate recovery mechanisms

– Initiate command control chunks

– Detect data loss for on-demand traffic

• Supports existing applications and communications with non-Cyclone networks

A p p lic a t io n L a y e r

C y c lo n e A d a p t a t io n L a y e r A p p lic a t io n In t e r fa c e (C A L -A )

C y c lo n e A d a p t a t io n L a y e r C y c lo n e In t e r fa c e (C A L -C )

S w it c h

C o n t ro lle r

Hos

t

Tem

pora

l Reg

ulat

or

A p p lic a t io n L a y e r

C A L -A

C A L -C

S w it c h

C o n t ro lle r

Hos

t

Tem

pora

l Reg

ulat

or

T C P

IP

N e t w o rkIn t e r fa c e

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Fault Handling

• Backup link approach– line condition monitor

– backup link pointer

– automatic switching to backup

• Application-dependent recovery mechanism

– primary and secondary connections

– altering partial or entirety of a path

• Reader-writer flag for handling timing variability

s lo t b u ffe r

p o in t e r b u f fe rf re e s lo t lis t

m a rk e r c h e c k e r

in c o m in glin k 1

b a c k u pin c o m in g

lin k 4

b a c k u po u t g o in g

lin k 3

o u t g o in glin k 1

controller

n e xt f re e s lo tp o in t e r

s witch

lin e c o n d it io n m o n it o r

3

in c o m in glin k 2

o u t g o in glin k 2

b a c k u pin c o m in g

lin k 3

b a c k u po u t g o in g

lin k 4

4

b a c k u p lin kp o in t e r

b a c k u p lin kp o in t e r

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Summary Of Scheduling Techniques

Cyclone Stop-and-Go Jitter-EDD W FQBounded Delay Y Y Y YBounded Jitter Y Y Y NBandwidthProtection

Y Y Y Y

Advantages Provides bounded delay and jitterNo additional operations duringdata transm ission.No header.Easy hardware im plem entation

Provides boundeddelay and jitterBounded bufferrequirem ent

Provides boundeddelay and jitterBounded bufferrequirem ent

Sm oothes bursts withoutpolicing

Disadvantages Clock synchronizationExplicit resource reservations

Coupled delay boundand bandwidthallocation

To reduce delay jitter,all packets received alarge delayCom plicateim plementation due toseparate regulatorCostly local delaybound com putation

Coupled delay boundand bandwidthallocationExpensive roundnum ber com putation

E-to-E DelayBound PH

N

mN

HT2

D (or HH

D)

max1 SH

Jitter Bound

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Performance Studies

• Data transfer

• Connection admission– long term connections

– single node and multiple nodes

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Type Of Traffic Studied

• Regularly spaced traffic

• Random pattern traffic

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Regularly Spaced Traffic (S5-S7)

0

20

40

60

80

100

1201 5 9

13

17

21

25

29

33

37

41

45

49

53

57

61

65

69

73

77

81

85

89

93

97

number of trials

nu

mb

er

of

slo

ts(S5: 5-10%) 97.33% Loading(S6: 10-20%) 94.32% Loading(S7: 5-33%) 95.24% Loading

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0

20

40

60

80

100

1201 5 9

13

17

21

25

29

33

37

41

45

49

53

57

61

65

69

73

77

81

85

89

93

97

number of trials

nu

mb

er

of

slo

tsnumber of additionally used slots after 15 requests

number of used slots before the first rejection

(S7) 98.1% Loading

trials 26-30 of (S7)

75

80

85

90

95

100

105

1 2 3 4 5

number of trials

nu

mb

er o

f sl

ots

number of additionally usedslots after 15 requests

number of used slots before thefirst rejection

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Random Pattern (S8)

0

20

40

60

80

100

120

0 20 40 60 80 100 120

% of available slots requested

p(a)

d-avg

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Random Pattern (S9)

01020304050

60708090

100

0 20 40 60 80 100 120

% of available slots requested

p(a)

d-avg

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Random Pattern (S10)

0

20

40

60

80

100

120

0 20 40 60 80 100 120

% of available slots requested

p(a)

d-avg

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Random Pattern (S11)

0

20

40

60

80

100

120

0 20 40 60 80 100 120

% of available slots requested

p(a)

d-avg

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Multiple Nodes

• Multiplied probability

• End-to-end delay is added

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Summary Of Performance Issues

• A couple of millisecond per node connection establishment overhead

• Close to 100% loading for identical, regularly spaced traffic

• Above 90% loading for regularly spaced traffic

• Above 80% loading for arbitrary pattern traffic, requesting 10% of bandwidth

• More than 50% of acceptance when links are 80% loaded, requesting 10% of bandwidth

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Summary

• Time-based resource management approach in networking

• All aspects of a computer network required to support time-based resource management

– both scheduled and on-demand traffic

– end-to-end resource usage scheduling in time

– calendar-based data movements

– existing applications and communications with non-Cyclone network

– fault condition handling

• The feasibility of Cyclone technology– end-to-end delay

– connection establishment overhead

– the probability of connection acceptance

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Advantages

• Temporal determinacy

• Loss free and jitter free end-to-end data delivery with minimal latency, without sustaining significant delays in connection establishment

• Nearly all of the bandwidth available for the actual transmission of data

• High loading without having any adverse impact on performance

• Well-suited for hardware implementation

• Highly scalable

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Limitations

• Temporal determinacy– temporal profile of a connection be known ahead

– not current practice in networking

• Handling applications with significant variability

• Synchronous system

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Open Issues

• Alternative designs and policies

• Optimization of many system parameters

• Design tradeoff and optimization for specific applications

• Dynamic monitoring of performance

• Support existing internetworking protocols other than TCP/IP

• Extensions to point-to-point links and point-to-point connections

• Hardware design

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Value Added

• Time-based resource management

• Alternate way of managing resources in networking– without requiring very accurate and highly synchronized clocks

– without consuming significant amount of bandwidth for handling timing variability

• Current applications with stringent timing requirement will perform better

• Lead to development of new classes of applications that are possible only when tight timing guarantee can be given

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Pathfinder

D

1S

3

checksumpaddingmarker S D 0 0 4

2

2 71 1 12 152 23 3 4 15 644

4

4

2

2

7

7

12

12

15

156

6

4

4

15

15

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Connection Establishment/Termination

A

B

C

D

E6

12

5

7

4

3