通信網(wǎng)絡(luò)與交換-ch5-傳送網(wǎng)

通信網(wǎng)絡(luò)與交換中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}14

傳送網(wǎng)傳輸介質(zhì)

波分復(fù)用SDH與網(wǎng)同步光傳送網(wǎng)設(shè)計(jì)中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}2中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}34.3SDH與網(wǎng)同步w{中國(guó)科學(xué)技術(shù)大學(xué)主干傳送網(wǎng)的特點(diǎn)主干傳送網(wǎng)坐落在電信網(wǎng)絡(luò)的提供傳輸服務(wù)。，為周邊的接入網(wǎng)絡(luò)主干傳送網(wǎng)通常具有mesh拓?fù)洌詾楦鹘尤刖W(wǎng)提供高效、靈活和可靠的互聯(lián)互通。電信網(wǎng)絡(luò)的設(shè)計(jì)理念:

pushing

the

in ligence

anddecision

making

into

the

access

networksandkee the

core

networkdumb

andfast.主干傳送網(wǎng)的主要功能：Traffic

aggregation

and

data

switchingCore{wei,zqzhu}學(xué)中國(guó)科學(xué)技術(shù)大光傳送網(wǎng)的體系結(jié)構(gòu)SONET/SDH層聚合低速率的數(shù)據(jù)流，并將它們整合在一起在波長(zhǎng)信道中傳輸：SONET/SDH

are

standardized

protocols

that

transfer

multiple

digitalbit

streams

over

optical

fibers.WDM(the

optical

layer)層是網(wǎng)絡(luò)體系的物理層，負(fù)責(zé)運(yùn)用波長(zhǎng)路由的方式建立高速數(shù)據(jù)通道。.IPSONET/SDHWDM{wei,zqzhu}中國(guó)科學(xué)技術(shù)大學(xué)Cross-Layer

Networking高速數(shù)據(jù)流通過全光的連接

(lightpaths)傳輸，每個(gè)連接占用一個(gè)波長(zhǎng)信道。Optical

circuit

switchingLightpath之間的數(shù)據(jù)轉(zhuǎn)發(fā)由高速

IP路由器實(shí)現(xiàn)Electrical

packet

switchingSONET/SDN是以上兩者之間的適配層，負(fù)責(zé)高速數(shù)據(jù)流的復(fù)用和解復(fù)用。中國(guó)科學(xué)技術(shù)大學(xué)SONET/SDH概述SONET:

Synchronous

Optical

NetworksNorth

AmericaSDH:

Synchronous

Digital

HierarchyEurope,

JapanSONET/SDHStandards

convergenceTime

division

multipleSynchronous

network網(wǎng)同步與同步復(fù)用（Synchronous

Multiplexing）異步復(fù)用中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}需要在數(shù)據(jù)流中填充比特以應(yīng)付時(shí)鐘差別。針對(duì)任意一個(gè)低速數(shù)據(jù)流的解復(fù)用都必須將整個(gè)高速流解復(fù)用。同步復(fù)用網(wǎng)絡(luò)中所有時(shí)鐘都完全同步（網(wǎng)同步）。數(shù)據(jù)的復(fù)用和解復(fù)用更加輕松靈活。SONET/SDH中的同步復(fù)用Basic

signal

rate

in

SONET:

51.84

Mb/sBasic

signal

rate

in

SDH:

155.52

Mb/s155.52

Mb/s速率的光通

口被成為OC-3(Optical

Carrier-3).OC-3:

155.52

Mb/s,

OC-12:

622.08Mb/sOC-24:

1.244

Gb/s,

OC-48:

2.488

Gb/sOC-192:

9.953

Gb/s,

OC-768:

39.814

Gb/s中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}104.4光傳送網(wǎng)設(shè)計(jì)光傳送網(wǎng)中的波長(zhǎng)路由中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Optical

Add/Drop

Multiplexer

(OADM)中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Reconfigurable

Optical

Add/Drop

Multiplexer

(ROADM)中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Optical

Cross-connect

(OXC)中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)設(shè)計(jì)的問題定義Network

Design（靜態(tài)問題）Given

a

set

of

connection

requests

(traffic

matrix),

networkdesign

inserts

network

resource

to

support

them

with

acost-effective

way.Static

problemas

the

requests

are

known.Network

Provisioning（動(dòng)態(tài)問題）Given

a

network

with

finite

resource,

network

provisioningallocates

network

resource

to

support

dynamic

connectionrequests.Dynamic

problem

as

the

requests

are

unknown.中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)設(shè)計(jì)的數(shù)學(xué)模型Physicaltopology:G(V,E),

G

is

the

topology,

V

is

the

setof

nodes,andE

is

the

set

of

links.Wavelength

channels

per

link:

WTraffic

Matrix:

a

NxN

matrix,

N

is

the

number

of

nodes

inthe

network,

and

(i,j)-th

element

is

the

average

trafficload

flowing

from

node

i

to

node

j.Design

objectives:

minimize

average

delay,

minimizeequipmentcost,minimizeenergy

consumption,

multi-objective

optimization.中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)設(shè)計(jì)的限制條件Wavelength

continuityAlong

the

routing

path,

the

wavelength

of

a

lightpath

cannot

bechanged

when

there

is

no

wavelength

conversion.CapacityThe

used

wavelength

channels

on

each

link

should

be

less

than

orequal

to

W.FlowAll

required

traffic

should

be

supported.Single-route中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)設(shè)計(jì)的基本任務(wù)Lightpath

routing

or

virtual

topology

designThe

nodes

of

the virtual

topology

correspond

to

the

nodes

in

thephysical

topology.Each

link

between

a

pair

of

nodes

in

the

virtual

topology

correspondsto

an

optical

lightpath

between

the

them.Wavelength

assignmentAssign

wavelength

channel

to

each

lightpath.Routing

and

wavelength

assignment

(RWA).中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}路由與波長(zhǎng)分配問題中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}關(guān)于路由問題的ILP模型中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}路由算法Solve

ILP

problemHeuristics中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Shortest

path

routing

(Dijkstra)K-Shortest

path

routingWeighted

path

routing

(modified

Dijkstra)Least

congested

path

routing

(load

balancing)Adaptive

shortest

path

routing…波長(zhǎng)分配Graph

Coloring

problem中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Construct

an

auxiliary

graphLightpaths

=>

nodes

in

the

auxiliary

graphIf

two

lightpaths

share

a

common

link

=>

a

linkbetween

the

corresponding

nodes

in

the

auxiliarygraphColor

the

nodes

in

the

auxiliary

with

minimalnumber

of

colors

such

that

no

adjacent

nodes

havethe

same

color波長(zhǎng)分配Heuristics-fit:

number

the

wavelength

on

the

links,available

wavelength

with

theand

use

thelowest

indexRandom-fitLeast-used:

assign

the

wavelength

that

is

leastused

in

the

network.Most-used:

assign

the

wavelength

that

ismostused

in

the

network.中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}電信網(wǎng)絡(luò)流量模型Erlang:

dimensionless

unit

for

the

statisticalmeasure

of

traffic

loadin

network.Carried

traffic:

Average

numberofconcurrentrequests

carried

by

the

network

over

a

period

oftime.One

Erlang

of

carried

traffic:

a

single

resourcebeing

incontinuous

use

for

a

period

oftime.中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}電信網(wǎng)絡(luò)流量模型Offered

traffic:

Average

number

of

concurrentrequests

arrived

in

the

network

over

a

period

oftime.Request

arrival

rate:

λ,

Poisson

process中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}Average

request-holdingdistributedErlang:

E=

λhtime:

h,

ExponentiallyBlocking:

there

is

no

enough

network

resource

toserve

the

offered

traffic.電信網(wǎng)絡(luò)中的阻塞率Assumption:

An

unsuccessful

request,

becauseof

insufficient

resource,

is

not

queued

or

retried,but

lost

forever.The

blockingprobability

Pb

of

a

path:

m:

#

of

wavelength

channels

on

the

pathE

=

λh:

offered

traffic

to

the

path中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)中的阻塞率In

WDM

mesh

network,

the

model

esmore

complicated

and

it

is

hard

to

provide

anytical

expression.Discrete

timesimulations:Generate

Network

TopologyGenerate

requests

for

a

service

periodTry

to

serve

the

requests

and

record

blockingsRepeat

2-3

until

statistical

accuracy

has

beenachieved.中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)中的阻塞率例子中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}光傳送網(wǎng)的網(wǎng)絡(luò)生存性Customers

lease

lightpaths

from

the

serviceprovider.A

Service-Level

Agreement

is

signed

to

makesure

the

provider

commits

to

providing

a

certainavailability

for

thelightpath.A

common

requirement:

the

lightpath

will

beavailable

99.999%of

thetime.Down-time

per

year:

5minutes中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}網(wǎng)絡(luò)生存性(0.9999999)100

<

0.99999!!中國(guó)科學(xué)技術(shù)大學(xué){wei,zqzhu}網(wǎng)絡(luò)生存性Therearemany

elementsalong

alightpath.The

only

practical

way

of

obtaining

99.999%availability

is

to

provide

service

continuouslywhen

failurespresent.Protection:

providing

redundant

capacity10

~

100

milliseconds

recovery

time.Restoration:

recovering

service

during

failure.1

~

10

seconds

recovery

time.中國(guó)科