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Why WAN-PHY

IEEE 802.3 Albuquerque meetingMarch 6-10, 2000

Paul Bottorff, Norival Figueira, David Martin

- Nortel Networks

Enrique Hernandez-Valencia Lucent Technologies (Bell Labs)

Nevin Jones Lucent Microelectronics

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Agenda• What is wrong with the Bridge solution

• What is wrong with the EoS solution

• How WAN-PHY solves the problems

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‘Ethernet over SONET (EoS)’a) An ANSI/ITU Proposed methodology for

mapping 802.3 Ethernet MAC frames intact intoSONET payloads.

b) The Path termination is at the interface betweenthe SONET MUX and the EoS mapping function.

c) This gets mapped over a system fully compliantwith all requirements of SONET/SDH standards.

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10Mb/s 802.3 802.3 PHY

802.3 PHY

802.3 PHY

802.3 PHY 802.3 MAC

802.3 MAC

802.3 MAC

802.3 MAC

802.1Relay

SO

NE

T M

UX

SONET100Mb/s 802.3

1Gb/s 802.3

100Mb/s 802.3

Brid ges fromEthernet to SONET

EoS

EoS

EoS

802.1Relay

EoS

E/O

Line

SONET

802.3 LAN Segment

Paths

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802.3 LAN PMA

802.3 LAN PCS

802.3 LAN PMD 3R

OC192802.3 LANLink Segment

SONETRegenerator

SONET

802.3 LAN Segment

802.3 MAC

802.3 LAN PMD

SONET MUX

Physical

Data Link

Higher Layers

Logical LinkControl

OSIReference

ModelLayers

LANCSMA/CD

Layers

RS

Bridge from Ethernet toSONET (OSI Layer model)

802.3 LAN PMA

802.3 LAN PCS

802.3 MAC

RS

802.1 Relay

EoS

SONETE/O

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So Why Bother With WAN-PHY• ANSI/ITU is working on a standard for

carrying Ethernet over SONET

• Just bridge from LAN-PHY into EoS

• The cost of a Bridge is low compared toOC-192 SONET optics

• Bridges are already being incorporated intoLTEs to provide Ethernet services

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What is wrong with this picture?

10 GigE LAN PHY

DWDM

EoS

Router

DWDM

EoS

EoS

WAN

MAN MAN

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

802.1Bridge

Router

Router

Router

Router

Router

Router

10 GigE LAN PHY

10 GigE LAN PHY

10 GigE LAN PHY

10 GigE LAN PHY

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Bridges Negate Router Protocols• IP traffic management does not work!! The bridges do not

support a traffic model compatible with current and futureIP traffic.

• IP routing is defeated!! The Bridges add traffic mergepoints outside the IP topology.

• The total buffer in the network is more than doubledgiving the network both longer latency and higher delayvariation.

• The bridges add unnecessary cost to the network.

• The Bridges limit the useful services a provider can offer

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To Fix It Take the Bridge Out Ofthe LTE

SO

NE

T M

UX

SONET

E/O

Line

SONET

802.3 LAN Segment

Paths

10Mb/s 802.3802.3 PHY

802.3 PHY

802.3 PHY

802.3 MAC

802.3 MAC

802.3 MAC

100Mb/s 802.3

1Gb/s 802.3

802.1Relay

EoS E/O E/O

E/O

E/O

Bridge(Router) LTE

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The “Bridge” Can Now Be aRouter

• IP traffic management works!! The bridgeis no longer an integral part of a carrierequipment.

• IP routing works!! The network no longerhas internal merge points.

• The storage in the network is reduced bymore than 50% reducing the latency bymore than 1/2.

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Better - But?

DWDM

EoS

Router

DWDM

EoS

EoS

WAN

MAN MAN

LTE

LTE LTE

LTE

LTE

LTE

LTELTE

Router

Router

Router

Router

Router

Router

EoS

EoS

EoS

EoS

LTE

LTELTE

EoS Router

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We still have some problems• We have tripled the SONET optical

components increasing the the cost of boththe LTE and the Router/Bridges

• The EoS interface is not specified in detaillimiting the vendors who can successfullybuild Router/Bridge interfaces

• Bridge/Routers will need to implement fullSONET management, SONET clock, andSONET systems for standard compliance

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The Solution Is WAN-PHY

SO

NE

T M

UX

SONET

E/O

Line

SONET

802.3 LAN Segment

Paths

10Mb/s 802.3802.3 PHY

802.3 PHY

802.3 PHY

802.3 MAC

802.3 MAC

802.3 MAC

100Mb/s 802.3

1Gb/s 802.3

802.1Relay

802.3MAC

802.3WANPHY

802.3WANPHY

802.3WANPHY

802.3WANPHY

Layer1 PathRelay

Layer1 PathRelay

Layer1 PathRelay

802.3 WAN PHY Segment

Bridge(Router) ELTE

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Best - Simple, Efficient, Low Cost

DWDM

EoS

Router

DWDM

EoS

EoS

WAN

MAN MAN

ELTE

ELTE ELTE

ELTE

ELTE

ELTE

ELTEELTE

Router

Router

Router

Router

Router

Router

10 GigEWAN PHY

10 GigE WAN PHY

10 GigEWAN PHY

10 GigEWAN PHY

ELTE

ELTEELTE

10 GigEWAN PHY

Router

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WAN-PHY Benefits• IP traffic management works

• IP routing works

• The network storage and latency is reducedby 50%

• IEEE standard gives a complete equipmentspecification enabling a universal WANinterface

• Ethernet’s low cost optics reduce the costof routers and LTEs

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A WAN Architecture Proposal

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802.

3 W

AN

PM

AD

escr

ambl

er

802.3 WAN PMA

802.3 WAN PCS

802.3 WAN PMD80

2.3

WA

NP

MD

SO

NE

TE

/O

SO

NE

TF

ramer

3R

Line

Section

Layer 1Path Relay

OC192

ELTE

GR253/1377Full “SONET” spec

802.

3 W

AN

Link

Seg

men

t

SONETRegenerator

λB

λΑ

Ethernet Line TerminationEquipment (ELTE )

SONET

802.3 WAN Segment

SONETPTE

802.3 MAC

MAC Client

Path

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802.3 WAN PMA

802.3 WAN PCS

802.3 WAN PMD 3R

Layer 1 Relay

OC192

Ethernet Line TerminationEquipment (non-muxed)

802.3 WANLink Segment

SONETRegenerator

λBλΑ

SONET

802.3 WAN Segment

802.3 MAC

802.3 WAN PMA

802.3 WAN PMD

SONET Framer

SONET E/O

Physical

Data Link

Higher Layers

Logical LinkControl

OSIReference

ModelLayers

CSMA/CDLayers

RS

Ethernet Line TerminationEquipment (ELTE )

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10Gb/sWAN 802.3

10Gb/sWAN 802.3

10Gb/sWAN 802.3

10Gb/sWAN 802.3

SO

NE

TO

/E

SO

NE

TF

ramer

3R

Line

Section

MUXOC768

WA

NP

MD

WA

NP

MA

desc

ram

’

WA

NP

MD

WA

NP

MD

WA

NP

MD

WA

NP

MA

desc

ram

’

WA

NP

MA

desc

ram

’

WA

NP

MA

desc

ram

’

Ethernet Line TerminationEquipment (muxed)

Ethernet LineTermination Equipment (ELTE )

SONETRegenerator

SONET

802.3 WAN Segment

Laye

r 1

Pat

hR

elay

Laye

r 1

Pat

hR

elay

Laye

r 1

Pat

hR

elay

Laye

r 1

Pat

hR

elay

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Point to Point SONET Interconnect

RegeneratorEthernet

LTEEthernet

LTE

WANPHY

WANPHY

SONET

802.3 WAN Segment

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Dark Fiber

WANPHY

WANPHY

802.3 WAN Segment

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DWDM Case

ELTE ELTE

SONET SONET

WANPHY

WANPHY

DWDMOpticalMUX

RegeneratorDWDMOpticalMUX

SONET

802.3 WAN Segment

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Backup

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WAN PHY DEFINITIONS

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Adhoc Contributors

Brad Booth Paul Bottorff

Ben Brown Roy Bynum

Steve Haddock David Law

Jeff Lynch David Martin

Stuart Robinson Geoff Thompson

Nader Vijeh

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Some definitions for us from802.3 and SONET

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‘802.3 MAC’a) 802.3 standard.

b) MAC client above.

c) Reconciliation sublayer below.

d) Single channel, no multiplexor.

e) Full duplex (for 10GbE), no CSMA/CD.

f) No buffering.

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‘802.1D Relay’a) Connects elements (eg MACs) at MAC-

client interface to create a bridge / switch.

b) A MAC client.

c) Packet store and forward (no cut through).

d) Accommodates speed changes port to port.

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‘802.3 Repeater’a) 10, 100, 1000 single speed.

b) Half-duplex, CSMA/CD only (no full-duplex).

c) Shared access to a single channel.

d) Bit store and forward for clock tolerancedifferences.

e) Fractional packet latency.

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‘Path’, ‘Line’, ‘Section’

Section Section

Line

Path(s)

Stratum Clock

Regenerator(STE)

LineTerminatingEquipment

(LTE)

LineTerminatingEquipment

(LTE)

LocalClock

LocalClock

Note: A Line can be longer than two Sections

PTE PTE

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‘SONET Regenerator’a) Full-duplex (dual-simplex).

b) Operates on one and only one wavelength in eachdirection.

c) Input wavelength equals the output wavelength ineach direction.

d) Forward wavelength may or may not equal thereverse wavelength.

e) Couples SONET Sections within a Line.

f) Buffer-less. Pipeline fixed delay. Transmit clockis the recovered receive clock.

continued ...

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‘SONET Regenerator’ (cont’)g) Examines and/or writes SONET section

overhead.

h) Payload, Line and Path information are passedthrough unmodified.

i) Unscrambles and re-scrambles to support g).

j) Keeps output Section active even if input Sectionfails (fault isolation).

k) This is a ‘3R’ (re-amplify, re-shape, re-time).

l) This is a ‘STE’ (Section Terminating Equipment)

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SONET ‘Line TerminatingEquipment (LTE)’

a) Everything a SONET Regenerator does plus:

b) Terminates a Line and the associated Section.

c) Operates on Stratum clock.

d) Multiplexes Paths onto a Line and de-multiplexesa Line into Paths.

e) It is a dual simplex Path mux.

f) Maintenance/Protection switching for muxedPaths between LTEs.

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SONET ‘Path TerminatingEquipment (PTE)’

a) Terminates a Path and the associated Line andSection.

b) Operates on Local clock.

c) This is where the SONET path overhead isprocessed.

d) This is the 802.3 WAN PHY.

e) In 802.3 this is where we attach the Reconciliationsublayer.

f) This is where the 802.3 MAC Frames are mappedinto the SONET payload.

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‘SONET Transponder’a) Couples differing optical PMDs back to back.b) E.G. wavelength 1 to wavelength 2, multimode to

singlemode, 850nm to 1300nm.c) Dual simplex.

‘Passive Transponder’ (emerging term) :

d) Transparently passes all bits (Items a, b, c).

‘Active Transponder’ (emerging term) :e) This is a special case of SONET Regenerator

because of item a).

f) Terminates Section (see Regenerator) and Line(see LTE).