OneClockNOMSpresentation.pdf

OneClock

to Rule Them All:

Using Time in Networked Applications

Tal Mizrahi, Yoram Moses

Technion – Israel Institute of Technology

Outline

•

Background

•

Generic protocol

•

Accurate scheduling

Using Accurate Time

Network-managed applications

using

accurate time

Power substations

Industrial automation

Particle accelerators

Coordinated

events

Coordinated

snapshot

Using Accurate Time

Network-managed applications

using

accurate time

Power substations

Industrial automation

Particle accelerators

Standard clock synchronization protocols

Network Time Protocol (NTP) [

RFC 5905

]

<

1msec

accuracy

Precision Time Protocol (PTP) [

IEEE 1588 2008

]

<

1

μ

sec

accuracy

OneClock to Rule Them All

O

NE

C

LOCK

A generic

protocol for

using

time.

An accurate

scheduling

Outline

•

Background

•

Generic protocol

•

Accurate scheduling

NETCONF in a Nutshell

server

client

rp

c

rp

c

-r

e

p

ly

time

NETCONF [

RFC 6241

]: Network Configuration Protocol

RPC: Remote Procedure Call

(Network Management

Station – NMS)

Generic Abstractions for Using Time

Client

Server 1

Server 2

...

Server n

T

T

T

Client

Server 1

Server 2

...

Server n

T

T

T

The NETCONF

Time

Capability

server

time

client

rp

c

(

T

s

)

rp

c

-r

e

p

ly

T

s

scheduled time

[

RFC 7758

] Time Capability in NETCONF

Scheduled RPC

The NETCONF

Time

Capability

server

client

rp

c

(g

e

t-tim

e

)

rp

c

-r

e

p

ly

(

T

e

)

T

e

RPC executed

time

rpc-reply reports the time of execution,

T

e

The NETCONF

Time

Capability

server

client

rp

c

(

T

s

,

g

e

t-tim

e

)

rp

c

-r

e

p

ly

(

T

e

)

T

e

T

s

RPC

executed

Scheduling & Reporting

The NETCONF

Time

Capability

Aborting an RPC

Scheduled RPC

Cancellation

server

client

rp

c

(T

s

)

rp

c

-r

e

p

ly

T

s

n

o

ti

fi

c

a

ti

o

n

c

a

n

c

e

l-s

c

h

e

d

u

le

RPC

not

executed

Outline

•

Background

•

Generic protocol

•

Accurate scheduling

T

e

T

s

T

s

’

time

(i)

(ii)

ETE

Elapsed Time of Execution (ETE)

Scheduled time

Actual start time

Completion time

(i) Start time

accuracy

ETE Measurement

server

client

rp

c

(

T

s

,

g

e

t-tim

e

)

rp

c

-r

e

p

ly

(

T

e

)

T

e

T

s

ETE

ETE is known

T

d

time

ETE

T

s

Prediction-based Approach

Desired

completion time

Scheduled time:

T

s

= T

d

- ETE

meas

ured T

e

ETE[n

] = T

e

- T

s

3

Scheduling:

rpc(

T

)

2

Predict next ETE value

1

ETE measurements

ETE[1], ETE[2], … , ETE[n-1]

Prediction Process

ETE[i] = the i

th

measured ETE value

Prediction Algorithms

Algorithm Description

Baseline

No prediction.

Average

The average of the last N measurements.

FT-Average The fault-tolerant average of the last N

measurements.

Outline

•

Background

•

Generic protocol

•

Accurate scheduling

•

Evaluation

Evaluation Method

•

NETCONF Time capability prototype.

–

Open source.

–

Based on OpenYuma.

•

Measurements on:

–

Amazon AWS.

–

Microsoft Azure.

–

DeterLab.

–

Emulab.

•

Periodic RPC transmission.

ETE

Measurement

Evaluation Results

Type I Type II Type III Type IV Type V Type VI

Mean

Abs

olute

Scheduling

Err

or

[seconds

-

log.]

Server Type

Baseline

Average

FT-Average

Kalman

Type Platform / class

I Amazon / t2.micro

II Azure / A0

III DeterLab / MicroCloud

IV DeterLab / pc2133

V Emulab / d710

VI DeterLab / bvx2200

•

Prediction approach reduces scheduling error by an order of magnitude.

•

The simple FT-Average provides the lowest error in most cases.

Outline

•

Background

•

Generic protocol

•

Accurate scheduling

•

Evaluation

The

Timed

Project

Conclusions

O

NE

C

LOCK

A prediction-based approach for

accurate scheduling

.

A generic protocol for

using time

in networked applications.

[RFC 7758]

-

Sensors

-

Actuators

-

IoT devices

-

Toasters

-

Switches

-

Routers

Thanks!

O

NE

C

LOCK

to rule them all,

O

NE

C

LOCK

to link them,

O

NE

C

LOCK

to time them all,

The

Project

Why do we need

time in SDN?

Scheduling

protocol

Accurate scheduling

method

SDN Clock

synchronization

R

EVERSE

PTP

[HotSDN ‘14, ISPCS ‘14]

T

IME

F

LIP

[INFOCOM ‘15]

O

NE

C

LOCK

[NOMS ‘16]

OpenFlow

Scheduled Bundles

[INFOCOM ’16, OpenFlow 1.5]

NETCONF

Time Capability

[NOMS ’16, RFC 7758]

Timed Consistent

Updates

[SOSR, ‘15]

O

C

to Rule

Them All

[NOMS, ‘16]

T

4: Dynamic

Path Updates

[INFOCOM, ‘16]

Data Plane

Timestamping

References

[1] T. Mizrahi, Y. Moses, “OneClock to Rule Them All: Using Time in Networked Applications”, IEEE/IFIP Network Operations and Management Symposium (NOMS), 2016.

(http://tx.technion.ac.il/~dew/OneClockNOMS.pdf)

[2] T. Mizrahi, Y. Moses, “Time Capability in NETCONF”, RFC 7758, IETF, 2016. (http://tools.ietf.org/html/rfc7758)

[3] T. Mizrahi, Y. Moses, “Software Defined Networks: It’s About Time", IEEE INFOCOM, 2016. (http://tx.technion.ac.il/~dew/Time4INFOCOM.pdf)

[4] T. Mizrahi, E. Saat, Y. Moses, "Timed Consistent Network Updates", ACM SIGCOMM Symposium on SDN Research (SOSR), 2015. (http://tx.technion.ac.il/~dew/TimedConsistentSOSR.pdf)

[5] T. Mizrahi, O. Rottenstreich, Y. Moses, "TimeFlip: Scheduling Network Updates with Timestamp-based TCAM Ranges", IEEE INFOCOM, 2015. (http://tx.technion.ac.il/~dew/TimeFlipINFOCOM.pdf)

[6] T. Mizrahi, Y. Moses, "Time-based Updates in Software Defined Networks", the second workshop on hot topics in software defined networks (HotSDN), 2013. (http://tx.technion.ac.il/~dew/TimeSDN.pdf) [7] T. Mizrahi, Y. Moses, "Time4: Time for SDN", arXiv preprint arXiv:1505.03421, 2016.