1-Tai Lieu OTN

1

Li m u

Khuyn ngh G.709 bt u c xy dng t T11/1988 vi cc quy nh lin quan cu trc

ghp ng b (Synchronous multiplexing structure) vi tc truyn ti s cao nht STM-16.

T2/2001, T chc ITU-T xy dng mi Khuyn ngh G.709, vi tn gi sa i Khuyn ngh

G.709/ Y.1331, xy dng cc quy nh lin quan giao din cho mng truyn ti quang

(interfaces for the Optical Transport Network) vi tc truyn ti s cao nht 40Gb/s. Tuy

nhin, ni dung Khuyn ngh thiu nhiu loi hnh dch v tc thp, nht l cc dch v gi.

Vi s pht trin ca cc loi dch v gi v TDM vi tc ngy cng cao, Khuyn ngh

G.709/ Y.1331 tip tc c sa b sung.

Theo cc ti liu trnh by phng n cho cc d n nng cp cc tuyn ca VTN lp t trong

2014, cc Hng ALU, Ciena, s cung cp thit b theo Khuyn ngh G.709/ Y.1331 phin

bn 3 (V3).

Khuyn ngh G.709/ Y.1331 V3 c T chc ITU-T pht trin t T4/2009, nhm thc hin cc

quy nh ghp n tng v nhiu ci tin khc ng thi h tr tc ln n 100Gb/s (100

Gbit/s support, one-stage multiplexing and other improvements).

Nhm phc v cng tc vn hnh khai thc, trin khai nhiu loi hnh dch v tng ng cc

giao din ca cc h thng thit b c lp trn mng VTN trong nm 2014 v tng lai,

PKTNVH bin son ti liu mng truyn ti quang OTN theo Khuyn ngh G.709/Y.1331 V3

v c b sung cc ni dung Khuyn ngh c hiu chnh n T10/2013.

Ni dung bin son ch gii hn n cc loi hnh dch v, giao din c cp trong cc

d n cung cp thit b cho VTN trong nm 2014. Cc loi cu trc khung v giao din c trong

Khuyn ngh G.709/Y.1331 V3 nhng cha c trnh by trong ti liu ny s c b sung

nu c VTN a vo khai thc trong tng lai.

Phn bin son khng trnh c thiu st ni dung v hnh thc, xin cm n cc gp gi v

PKTNVH TT2 ti liu tip tc c b sung v hon chnh.

Phng K thut Nghip v iu hnh

2

Phn I : C s v mng truyn ti quang OTN (Optical Transport Network)

1. Th no l mng truyn ti quang OTN (Optical Transport Network) ?

Cc nh cung cp dch v vin thng hin ang phi i mt vi nhiu kh khn, thch thc t

s st gim doanh thu ca cc dch v thoi truyn thng, cnh tranh gia tng, chi ph leo thang

cng nh s bng n ca lu lng d liu. Bo co ca T-Mobile trong Hnh 1.1 cho thy vic

s dng d liu di ng trn in thoi thng minh tng t 25 MB/ngi dng/thng nm

2009 ln 760 MB vo nm 2012, vi tc tng trng hai ch s hng nm (CAGR) trn

200%. S pht trin mnh m ca cc mng 4G s ch tip tc y nhanh xu hng ny, tc

ti tin download mng di ng 4G c th tng gp 10 ln mt khi mng 4G c trin khai rng

ri.

Theo Economist, mc tiu th d liu Internet ti hu ht cc quc gia c d bo s tng gp

ba ln t nm 2010 n nm 2015, ti cc quc gia pht trin con s ny s vt 30 GB/ngi

dng/thng. Vi ch 33% dn s th gii hin nay c th truy cp Internet, th s tng trng

dng nh khng c du hiu chm li sm.

Hnh 1. 1 : Tc tng trng lu lng d liu Internet

1.1 Cc yu cu ca mng quang qun l bng thng mng quang DWDM 100G, 500G, 1Tb/s.

1.1.1 Cc yu t thc y hin i ho mng thng tin quang

3

p ng tc tng trng lu lng d liu Internet, cc nh sn xut thit b vin thng

ng dng cng ngh ghp bc sng quang WDM kt hp vi h thng thit b truyn dn SDH

truyn thng.

Trong cng ngh ghp bc sng quang WDM, lu lng c gia tng trn cng mt si

quang bng cch gi i cng lc trn cng si quang nhiu tn hiu c bc sng ring ca

chng, khng phi l tng tc ca mt tn hiu duy nht (v d gi 16 tn hiu 10Gb/s, mi tn

hiu 10Gb/s s trn bc sng ring ca chng, ch khng phi gi i l duy nht ch 1 lung

160Gb/s). Ghp nh vy c gi l ghp knh phn chia bc sng WDM (wavelength-

division multiplexing).

H thng WDM gi mi tn hiu quang nh dng gc ca n ch khng phi l lp nh x

vo ti tin ca mt tn hiu khc nh trong h thng SONET/SDH. Phng thc ghp knh phn

chia bc sng WDM s gy kh cho mt nh iu hnh mng trong vic cung cp s khai thc,

qun l , bo tr, v d phng ( OAM & P) cho mi tn hiu nu n c s dng vi nh dng

tn hiu gc, v iu ny s i hi c thm cc h thng qun l ph thuc vo tn hiu ca

khch hng. Vn ny c bit ng vi cc tn hiu ca cc knh truyn hnh.

Do cc h thng thit b c nn tng l cng ngh truyn dn SDH v ghp bc sng quang

WDM c cung cp bi nhiu hng sn xut thit b khc nhau v WDM khng c giao thc

tiu chun nh x lu lng vo h thng thit b (nh trnh by trn), cho nn vic gim

st cht lng v tnh ton vn tn hiu gp nhiu kh khn, hiu qu hot ng khng cao.

Vic pht trin mt nh dng tn hiu mi cho cc tn hiu WDM (thay v ch s dng cc tn

hiu SONET/SDH hin c) l kh nng thm cc knh dnh cho tiu mi s cung cp cho cc

tnh nng b sung cn thit thc hin c hiu qu cc chc nng OAM & P trn mng WDM.

Mt l do khc cho vic pht trin mt tiu chun mi dnh cho cc tn hiu WDM l cung cp

mt phng tin c kh nng sa li mnh m hn. H thng SDH truyn thng c mt kh

nng sa li chuyn tip FEC tng i khim tn. Khi tn hiu i qua mt mng quang a-

chng, t s tn hiu trn tp m SNR b gim. V cc nh khai thc mng mong mun gia tng

khong cch truyn dn v tc bit mi bc sng, sa li chuyn tip FEC ca h thng SDH

FEC khng phi lun lun p ng c. Cui cng, mt l do khc cho tiu chun mi dnh

cho truyn ti WDM l cung cp mt kh nng ng gi ti tin truyn ti lu lng khch

4

hng c nhn c bng thng cao hn c tch hp t cc mng truy cp. V d, nu lu lng

ca khch hng cn bng thng chuyn mch cui cng nh nht trong mng l mt tuyn lin

kt Gigabit Ethernet duy nht th vic cung cp chuyn mch trong mng truyn ti vi tc

STS-1s ( 51,84 Mbps) s lm pht sinh chi ph v s phc tp trong mng.

Ngoi ra, cc kin trc vng (ring) SDH thng c s dng bo v cc thay i theo a l

vn khng hiu qu, lng ph n 50% tng bng thng mng. Thc t l nhng thit b c ny

gn ht tui th v khng th p ng c nhu cu ca cc mng hin nay. Do bt buc

cc nh cung cp dch v phi nng cp mng, nhng nng cp ci g v nng cp nh th no

li l mt vn ?

Vi nhiu u im so vi h thng SDH v WDM truyn thng, cc thit b mng truyn ti

quang OTN (Optical Transport Network) tr thnh nn tng h tng thng tin thay th tip

theo cho h thng SDH. D bo ca Infonetics cho thy mc chi tiu cho cng ngh OTN s

tng t con s di 50% tng mc chi tiu quang trong nm 2011 ln 80% vo nm 2016.

OTN cung cp cc tnh nng qun l v gim st tt trn h tng thit b cng nh kh nng

truyn ti. Ngoi ra cc c im quan trng khin cho OTN tr nn hp dn l kh nng ng

gi, cho php qun l hiu nng dch v khch hng n 2 u cui (end-to-end), ghp cc

khung tn hiu ODU tc thp thnh cc khung tn hiu OTN tc cao hn nhiu ln

truyn ti v kh nng h tr i vi nhiu tng dch v c ti u ha v tr, khong cch,

tnh hiu qu v/hoc chi ph. Do , h thng thng tin vi nn tng cng ngh OTN thc s

chim lnh c th trng v thay th cc h thng mng SDH c truyn thng.

Vic trin khai h thng thng tin cu hnh li (mesh) vi nn tng cng ngh OTN cn gip

gii phng dung lng ri trong mng m trc y c dnh cho vic bo v ring. Nh ,

cc nh cung cp dch v c th khai thc thm nhng ngun doanh thu mi t vic a ra cc

gi cc dch v c nhiu c tnh linh hot khc nhau v kh dng, tr v dung lng

qua nng cao li nhun v kh nng cnh tranh. Ngoi ra, vi kh nng qun l, gim st v

thng k t tr, mng OTN gip vic trin khai cc dch v mi nhanh hn, d dng hn. Bn

cnh l nhng li ch lin quan ti vic gim chi ph v tng tnh hiu qu m OTN cung cp.

1.1.2 Hin i ho mng thng tin trn nn tng cng ngh OTN

5

Vic chuyn i sang cc thit b th h k tip cho php cc nh cung cp dch v ci thin hiu

qu s dng in: in nng cn thit truyn ti d liu gim t trn 200W/GB xung

di 10W/GB trong 10 nm qua. Thng thng vic x l thng tin s tiu th khong 20W/GB

d liu, vt qu 10 ln in nng cn thit cho chuyn mch ghp bc sng quang DWDM.

Trong , khong 60% lu lng c x l bi mt b nh tuyn li l lu lng chuyn tip.

V th vi gii php b qua b nh tuyn li s gip mng OTN tit kim ng k chi ph do

khng cn phi c chuyn i qua li quang in quang t cc b nh tuyn (Hnh 1.2). C

th l s dng cc chuyn mch OTN tc 10G ch gi lu lng cn phi c x l ti

b nh tuyn v cho php nhng lu lng cn li chuyn tip nhanh v tc cao qua cc

tuyn quang OTN. Do gim ng k OPEX (mc tiu th in nng) ti b nh tuyn. Ngoi

ra, tip cn ny gip ti s dng hiu qu cc cng 10G hin c trn cc thit b nh tuyn, dn

n tit kim ng k CAPEX do khng cn phi nng cp ln cc cng 40/100G t tin, chi

ph ny gp i chi ph ca cc cng OTN.

Hnh 1. 2 : B qua b nh tuyn li thay bng vic s dng chuyn mch OTN

Cc tiu chun truyn ti quang SDH/SONET b gii hn tc ti a l 40Gb/s. Khi vic p

dng cc cng ngh quang nht qun (coherent optical system) tip tc c y mnh, truyn

ti ng di tc 100Gb/s v cao hn tr nn hiu qu kinh t hn. Do h thng

quang SDH/SONET s l ro cn hn ch truyn ti tn hiu quang cc tc cao hn 40Gb/s.

Cc tiu chun truyn ti quang OTN, vi s h tr ca cc cu trc khung ODU-0 v

ODUFlex, cho php ghp knh hiu qu cc tn hiu tc thp thnh cc tc cao hn

6

truyn ti trn tuyn quang. iu ny gip nng cao hiu qu truyn ti trn cc mng ng

trc, gim thiu nguy c b cn kit dung lng ng quang cng nh s cn thit phi trin

khai thm nhng tuyn quang mi, do gim c ng k chi ph. Ngoi ra, cc cng dung

lng cao hn cng gip n gin ha vic qun l v gim khi lng lu lng lng ph, do

tit kim chi ph vn hnh hn.

Cc nghin cu vi mt nh cung cp truyn thng ng trc Bc M v mt nh khai thc

khu vc ti n ch ra rng vic chuyn t cu hnh ring SDH sang cu hnh li (mesh)

theo cc tiu chun truyn ti quang OTN gip gim 40% s lng cc knh 10Gb/s cn thit.

T chc ITU-T pht trin mt b tiu chun mng truyn ti quang OTN trong Khuyn ngh

ITU-T Rec G.709, bao gm cc bc sng v cc nh dng tn hiu h tr tt hn ghp ca

mt s lng ng k ca tn hiu vo mt si quang n. Tiu chun ITU-T Rec G.709 dnh

cho cc tn hiu Ghp Phn chia Bc sng quang WDM (Wavelength Division Multiplexed )

v bao gm cc tiu chun nh dng v h thng phn cp tn hiu s bao gm cc tn hiu k

thut s v bao gm cc tiu vn hnh khai thc&kim tra cht lng OAM & P. Cc tiu

OAM&P l mt phn ca nh dng tn hiu.

OTN (Optical Transport Network) trong Khuyn ngh ITU-T Rec G.709 l giao thc Lp 1 mi

c chun ha bi Nhm Nghin cu 15 ca t chc ITU-T (ITU-T Study Group 15). Giao

thc Lp 1 ny c mc ch l truyn ti cc tn hiu a-Gigabit i qua mt c s h tng h

thng mng cp quang. Cng ngh OTN thay th cho cng ngh SDH truyn thng v c

thit k gii quyt nhng thch thc ca mt c s h tng h thng vin thng tc cao, a

dch v v c nn tng mng gi Ethernet.

Trong bi cnh ny v so snh vi cng ngh SDH truyn thng, cng ngh OTN c cc yu t

mi :

1) S dng Chuyn tip Sa li FEC (Forward Error Correction) dnh ring thc hin

cc thut ton x l tn hiu k thut s nhm ci thin hiu qu tc li bit BER (Bit

Error Rate) ca cc tuyn lin kt quang. S ci thin bin BER ln n bc 8 hoc

cao hn.

2) OTN c ti u ha cho cc dch v Ethernet. OTN l mt cng ngh khng ng b,

khng c cc yu cu ng b ha. Hn na, OTN vn chuyn tn hiu ca khch hng

7

trong ton b c s h tng h thng vin thng ca h khng cn tch ra cc thng tin

tiu (overhead information). V d mng OTN s cung cp kt ni thc s trong sut

v minh bch cho cc dch v da trn gi Ethernet (1GE , 10GE , vv).

3) Cc tc c bn chi tit (basic granularity) ca mng OTN l mt b cha 1.25Gbps c

k hiu l ODU0. OTN cng kt hp mt phng php thit lp nh x mi c gi l

Th tc nh x Tng qut GMP (Generic Mapping Procedure). Th tc nh x Tng

qut GMP cho php h tr vic vn chuyn trong sut v minh bch cc tn hiu ca

khch hng c tc bit bt k. V d mt tn hiu khch hng 1GE s c cung cp

bi ton b mt b cha ODU0 c tc l 1.25Gbps.

C mt s loi khc nhau ca cc thit b mng truyn ti quang c trin khai da trn cc

tiu chun OTN. Cc loi ph bin nht bao gm:

1) Thit b ti to (Regenerators),

2) Thit b u cui OTN,

3) Thit b Ghp Xen/Rp Quang OADMs(Optical Add/Drop Multiplexer),

4) Thit b Ghp Xen/Rp Quang Ti cu hnh ROADMs(Reconfigurable Optical Add/Drop

Multiplexer),

5) Thit b kt ni cho quang OXCs(Optical cross connect).

Thit b u cui OTN c s dng cho cc kt ni im-im thng qua mng li WDM,

thit lp nh x cc tn hiu ca khch hng vo khung ti tin OPU, i khi ghp nhiu tn hiu

trong cng min in, v cui cng thc hin thit lp nh x/ghp trong min quang. OADMs,

OXCs, v mt s loi thit b ti to (Regenerators) ch yu x l cc tn hiu OTN trong min

quang. Trong nhng nm gn y, thit b ROADMs tr nn ph bin. Cc khi xy dng

quan trng ca nt ROADM c th c phn loi thnh ba chc nng chnh :

1) B lc xen/rt bc sng hoc chuyn mch bc sng B phn ny c gi tng

qut l phn thit b h tng (wavelength fabric) bc sng v ch hot ng trong min

quang. Tuy nhin , n c th c thc hin vi mt s cng ngh khc nhau, bao gm

cng ngh chn bc sng (wavelength blockers) v cng ngh chuyn mch chn lc

1.2 V tr ca lp mng OTN trong mng ghp bc sng quang DWDM

1.3. Cc thit b mng truyn ti quang OTN

8

bc sng WSSs (Wavelength Selective Switches). Phn thit b h tng bc sng thc

hin ghp v gii ghp tt c cc bc sng DWDM ring r t cc card giao din khch

hng. Phn thit b h tng bc sng cng cung cp chc nng bo v quang cho cc

bc sng.

2) B iu khin cng sut ng v gim st t xa ti lp quang - B phn ny l phn thit

b khuch i quang kt hp vi b tn sc v cn bng li c cc chc nng iu

khin cng sut ng v gim st t xa cho s hin din/vng mt ca cc tn hiu quang.

3) B to v kt cui knh dch v quang - ROADM th h tip theo, nh minh ha trong

Hnh 1.4, c thm chc nng chuyn mch trong min in.

Hnh 1.3 : S ca thit b ROADM th h sau.

Chuyn mch min in c th TDM, chuyn mch gi, hoc c hai. ng lc cho

ROADM th h tip theo ny l cho php xen\rt cc tn hiu ca khch hng trong cc

tn hiu mang trn mi bc sng, thay v phi xen\rt ton b bc sng. Tnh nng

xen\rt tn hiu tinh vi hn (granularity) ny cho php tch hp hoc m rng dung lng

lu lng khch hng s gip s dng hiu qu hn ca cc bc sng. Tnh nng

xen\rt tn hiu tinh vi hn cng cho php cu hnh mng linh hot hn. Cc ROADM

thc hin cc chc nng xen/rt cc tn hiu SDH truyn thng trn cc bc sng c

mang cc tn hiu SDH.

9

Mng ghp bc sng quang WDM da trn cc tiu chun OTN G.709 ang tr nn ngy cng

quan trng. Cc l do cc nh khai thc mng thng tin chuyn hng v cng ngh OTN l :

1) OTN l mt cng ngh t phc tp cho cc ng dng truyn ti tc cao hn so vi h

thng cng ngh SDH c.

2) Cc tn hiu OTN kt hp tiu c ti u ha vn chuyn cc tn hiu trn cc

mng WDM ca cc nh khai thc mng thng tin.

3) S kt hp ca phc tp cng ngh gim vi ti u ha tiu , cho php gim ng k

trong chi ph khai thc mng ca cc nh khai thc mng thng tin.

4) Mng OTN cho php ghp bng thng chi tit (granularity) vi ln cao hn mt hoc

hai bc so vi h thng SDH, do lm cho cc nh khai thc mng thng tin c kh nng

tng m rng dung lng ln cc tc cao hn.

5) OTN hin nay cung cp mt phng php hiu qu v chi ph truyn ti cc tn hiu d

liu khch hng ca mng din rng (WAN) tc cao s dng bao gm cc giao thc

Ethernet v giao thc mng li lu tr khu vc SAN (storage area network).

6) OTN cung cp mt c ch tch hp sa cha li chuyn tip FEC (forward error

correction) cho php kh nng t n tc bit cao hn gia cc nt mng quang trn

cng mt si quang ca tuyn lin kt.

7) Cc tn hiu khch hng c th c vn chuyn trn mng OTN mt cch trong sut. Tnh

trong sut ny cng bao gm cho tn hiu c ngun gc SDH dnh cho cc ng dng nh

mng ca nh mng ("carriers carrier "), ngha l cc nh khai thc mng SDH truyn

thng c li s dng cc dch v truyn ti thng tin ca cc nh khai thc mng OTN. Khi

ton b ton b phn tiu ca cc tn hiu khch hng SDH phi c bo ton, khi

cc tn hiu SDH ca cc nh khai thc mng SDH truyn ti qua mng OTN ca cc nh

khai thc mng OTN. Ni cch khc, nh trnh by trong Hnh 1.5, mng OTN cung cp

mt cng ngh truyn ti lu lng hi t ti u v trong sut cho cc tn hiu khch hng

truyn thng quan trng hoc ang pht trin mi.

1.4 Tnh hiu qa ca mng OTN trong mng DWDM 100G, 500G, 1Tb/s

1.4.1 Cc u im ca mng OTN so vi mng SDH truyn thng

10

Hnh 1.4 : Mng OTN cung cp mt cng ngh truyn ti lu lng hi t ti u

Tm li, mng OTN cung cp nhng u im sau so vi mng SDH truyn thng :

1) Sa li Chuyn tip FCC mnh hn (Forward Error Correction);

2) C nhiu mc Gim st Kt ni B i TCM (Tandem Connection Monitoring);

3) Truyn ti trong sut cc tn hiu Khch hng;

4) Kh nng m rng dung lng chuyn mch (Switching Scalability).

c c cc tnh nng hiu qa truyn ti p ng cho yu cu dung lng ny cng cao v

nhiu loi hnh dch v TDM v gi nh khai thc cn trang b mi hon ton cc h thng phn

cng v phn mm ca thit b OTN. Cc thit b SDH truyn thng c tr thnh cc khch

hng i vi mng OTN.

2. Cc c im mi ca mng OTN

Mc 1 trnh by tng quan xu th pht trin ca mng truyn ti vin thng OTN. Mng OTN

p ng yu cu pht trin dch v ngy cng cao nh c cc c im ni tri c trnh by

sau y.

Sa li Chuyn tip FCC l mt tnh nng chnh ca h thng OTN. Chng ta bit khung tn

hiu SDH c mt b sa li chuyn tip FCC. B sa li chuyn tip FCC trong khung tn

hiu SDH s dng cc byte tiu on SOH (Section Overhead) truyn ti cc thng tin

kim tra sa li chuyn tip FEC v do c gi l loi sa li chuyn tip FCC trong bng

1.4.2. Nhc im ca mng OTN

2.1 Sa li Chuyn tip FCC (Forward Error Correction)

11

(in-band FEC). B sa li chuyn tip FCC ca khung tn hiu SDH cho php ch c mt s hn

ch v thng tin kim tra sa li chuyn tip FEC, cho nn lm hn ch hiu qu hot ng sa

li ca FEC.

i vi khung tn hiu OTN, s sa li chuyn tip FCC (schemes) s dng mt m ho xen

k gm 16 byte, c tn gi l Reed-Solomon. Sa li chuyn tip FCC ca OTN s dng 4x256

bytes thng tin dnh cho vic kim tra mi khung tn hiu ODU. Thm na, s sa li

chuyn tip FEC nng cao tu theo mi nh sn xut thit b OTN (c quyn) c cho php

mt cch r rng v s dng rng ri.

Sa li chuyn tip FEC c chng minh l c hiu qu trong cc h thng thng tin trn

cc tuyn quang c OSNR hn ch, cng nh trong cc h thng h thng thng tin quang b

hn ch v tn sc. Cc hiu ng phi tuyn ca tuyn quang DWDM lm gim cng sut u ra

dn n nhng hn ch v OSNR ca tuyn quang, khi sa li chuyn tip FEC rt hu ch

gia tng cht lng tn hiu thu b cho s suy gim OSNR ca tn hiu truyn trn tuyn

quang. Tuy nhin, sa li chuyn tip FEC c hiu qu t hn, khi c s dng b cho cc

hn ch do tn sc phn cc PMD trn tuyn quang.

Khuyn ngh G.709 nh ngha mt b Sa li Chuyn tip FCC dnh cho tn hiu OTN hiu

qa hn, so vi tn hiu SDH truyn thng. B Sa li Chuyn tip FCC ca tn hiu OTN cho

php s ci thin t s tn hiu trn tp m SNR (Signal Noise Ratio) ln n 6,2 dB. Mt cch

khc din gii cho gi tr ci thin SNR 6,2 dB l truyn mt tn hiu tng ng cng mt

tc li bit BER (Bit Error Rate) xc nh trc th b khuch i cng sut quang phi cn

lng cng sut pht nhiu hn l 6,2 dB nu khng s dng Sa li Chuyn tip FCC ca tn

hiu OTN. Ngc li, nu s dng Sa li Chuyn tip FCC ca tn hiu OTN b khuch i

cng sut quang ch cn pht lng cng sut gim i 6,2 db thu c tn hiu vi cng mt

tc li bit BER. Lng SNR 6,2 dB ny cn c gi l li m ha ca b Sa li

Chuyn tip FCC.

li m ha t c nh Sa li Chuyn tip FCC ca tn hiu OTN c th c s dng :

1) Tng chiu di chng quang (span) ti a v/hoc s lng chng ca mt tuyn quang kt

ni gia 2 nt mng lin tip, nh vy m rng c ly truyn dn ca tuyn quang. (Lu

rng iu ny ch ng vi gi nh rng cc nh hng suy yu tn hiu khc nh tn sc

12

mu v tn sc phn cc (chromatic and polarization mode dispersion) khng tr thnh cc

yu t hn ch c ly truyn dn).

2) Tng s lng cc knh DWDM trong mt h thng DWDM b gii hn bi cng sut u

ra ca b khuch i quang bng cch gim cng sut cho mi knh quang v tng s lng

cc knh quang ca h thng DWDM. ( Lu rng phi tnh n nhng thay i tc ng

cc hiu ng phi tuyn tnh do s gim cng sut mi knh quang ca h thng DWDM).

3) Gim nh cc tham s thnh phn (v d nh cng sut pht ra, mt n mt, t l phn bit

(extinction ratio), h s ting n NF (noise figures), h s cch ly b lc ) cho cc giao din

ca mt tuyn lin kt quang xc nh trc v do lm gim chi ph thnh phn.

4) Nhng quan trng nht, Sa li Chuyn tip FEC lm gia tng kh nng truyn dn cho

cc mng quang trong sut : Cc phn t ca mng quang trong sut nh trm OADMs v

trm OXCs s pht sinh ra cc khim khuyt v quang nghim trng (v d nh lm suy hao

tn hiu). Do iu ny lm hn ch nhiu v s lng cc phn t ca mng quang trong

sut c th c vt qua, bng mt ng dn quang trc khi tn hiu cn c ti sinh

3R. Nh Sa li Chuyn tip FEC, mt ng dn quang c th vt qua mt s lng cc

phn t nhiu hn ca mng quang trong sut. iu ny cho php pht trin t cc tuyn

quang lin kt im- im ph bin hin nay tin n cc mng quang mt li trong sut

vi y chc nng.

Hnh 2.1 : FEC ci thin cht lng truyn ti c 6dB ti BER=10E-15

13

Chng ta bit chc nng gim st mng SDH truyn thng c chia thnh 3 loi : gim st

phn khc (section), gim st ng (line) v gim st ng dn (path). Mt vn pht sinh

khi bn gp trng hp "nh Khai thc ca nh Khai thc " (Carriers Carrier) nh th hin

trong Hnh 2.2, ni mt nh Khai thc cn gim st mt on (segment) ca ng dn

(path) i xuyn qua mng ca nh Khai thc khc.

Hnh 2.2 : Gim st Kt ni B i TCM (Tandem Connection Monitoring)

y nh Khai thc A c mt nhu cu thu nh Khai thc B truyn ti tn hiu ca mnh.

Tuy nhin, nh Khai thc A cng cn mt cch theo di cc tn hiu ca A khi n i qua

mng li c iu hnh bi nh Khai thc B. y c gi l mt "kt ni b i TC"

(Tandem connection). Kt ni b i TC l mt lp nm gia Gim st ng (Line) v Gim

st ng dn (path). Mng SDH truyn thng cho php ch mt kt ni b i TC duy nht.

Mng OTN theo tiu chun G.709 cho php n 6 kt ni b i TC.

Trong Hnh 2.2, kt ni b i TC1 c s dng bi ngi dng gim st cht lng dch

v (QoS) ca chnh ngi dng. Kt ni b i TC2 c s dng bi cc nh Khai thc u

tin ( y l nh Khai thc A) theo di cht lng dch v QoS ti 2 u cui (end-to-end) ca

nh Khai thc A. Kt ni b i TC3 c s dng trong cc min khc nhau theo di cht

2.2 Gim st Kt ni B i TCM (Tandem Connection Monitoring)

14

lng dch v bn trong mi min (hoc ca nh Khai thc A hoc ca nh Khai thc B theo di

cht lng dch v). Sau kt ni b i TC4 c s dng theo di gim st s bo v bi

nh Khai thc B. Tuy nhin, khng c tiu chun xc nh nh Khai thc no s dng TCM. Cc

nh Khai thc phi c mt tha thun, h khng xung t trong qun l v khai thc cc

TCM.

i vi mng OTN cc tn hiu SDH y c gi l cc tn hiu khch hng (client

signals). G.709 nh ngha khung OPUk c th cha ton b tn hiu SDH. iu ny

c ngha rng ngi ta c th truyn ti bn tn hiu khch hng STM-16 trong mt

khung OTU2 v khng cn phi sa i bt k g trong phn tiu SDH. Do vic

vn chuyn cc tn hiu ca khch hng trong mng OTN nh vy l trong sut n bit

(tc l tnh ton vn ca ton b tn hiu khch hng c bo ton khi truyn ti qua

mng OTN).

Vic vn chuyn cc tn hiu ca khch hng trong mng OTN cng trong sut v thi

gian (timing transparent). Kiu nh x khng ng b ca mng OTN s truyn t trng

thi thi gian ca tn hiu u vo (l tn hiu khch hng c nh x khng ng b

vo cc khung tn hiu ca mng OTN) i n u cui pha u xa (far-end) ( thit b

thu pha u xa tn hiu khch hng c gii nh x khng ng b khi cc khung tn

hiu ca mng OTN).

Vic vn chuyn cc tn hiu ca khch hng trong mng OTN cng trong sut v tr

(delay transparent). V d, nu bn tn hiu khch hng STM-16 c nh x vo khung

tn hiu ODU1 v sau c ghp vo mt khung ODU2, mi quan h thi gian ca

bn tn hiu khch hng STM-16 vn c bo tn cho n khi chng c gii nh x

(demapped) quay tr li khung tn hiu ODU1.

Khi h thng SDH c pht trin trong thp nin tm mi vi mc ch chnh ca n l

cung cp cc cng ngh truyn ti cho cc dch v thoi. Do hai cp chuyn mch ca h

thng SDH c xc nh nh sau :

2.3 Truyn ti trong sut cc tn hiu khch hng mng OTN

2.4 M rng dung lng chuyn mch (Switching Scalability)

15

Cp chuyn mch bc thp c thc hin mc tc 2 Mbit/s h tr trc tip

cc tn hiu thoi E1,

Cp chuyn mch bc cao hn c thc hin mc tc 150 Mbit/s dnh cho cc

k thut lu lng.

Cc cp chuyn mch tc bit cao hn ca h thng SDH vn cha c xc nh trc.

Thi gian sau, tc ng truyn tng ln trong khi tc chuyn mch ca h thng SDH

vn gi c nh. Khong cch gia tc ng truyn v tc bit chuyn mch ca h thng

SDH ngy cng m rng. Ngoi ra cc dch v mi cc tc bit cao hn (dch v IP, cc

dch v Ethernet) phi c h tr bi h thng SDH.

H thng thit b SDH th h tip theo (Next Generation-SDH) a ra cc gii php lin kt

lin tc v o (contiguous and virtual concatenation) cc khung SDH truyn thng, gii quyt

mt phn ca vn v truyn ti dch v gi. Cc gii php lin kt lin tc v o cho php h

tr truyn ti cc loi dch v gi theo cc tc bit chuyn mch ca tiu chun SDH. Tuy

nhin khong cch gia tc truyn trn ng dy hay tc bit dch v vi tc bit

chuyn mch vn cn tn ti, ngay c i vi chuyn mch lin kt (concatenation switching)

c thc hin cp VC-4.

Khi thc hin ghp 4x10G thnh mt tn hiu 40G, thit b SDH phi x l ln n 256 VC-4.

iu ny dn n nhiu ch ph trong cc thit b phn cng, cng nh nhiu n lc trong qun

l v khai thc.

thit k thit b v mng khai thc c hiu qu, thit b c kh nng chuyn mch tc

bit cao hn cn phi c sn xut.

Gii php chuyn mch lng t (photonic switching) ca cc bc sng c xut.

Nhng vi chuyn mch lng t, tc bit chuyn mch phi gn vi tc bit ca bc sng

v nh vy c s ph thuc gia tc bit ca bc sng vi tc dch v. Khi mt la

chn c lp gia cc tc bit dch v v cng ngh DWDM l khng th thc hin c. V

d mt nh khai thc cung cp dch v lin kt IP c tc 2,5 Gbit/s s cn mt h thng

DWDM Nx2.5G. Khi thm cc dch v 10G cho khc hng, nh khai thc phi nng cp mt

s bc sng ca h thng DWDM ln tc 10G. iu ny s dn n thit k mng khng

hiu qu.

16

Thit b OTN cung cp gii php thay th cho vn ny bng cch thit lp khng hn ch v

tc bit c chuyn mch. Khi tc ng dy tng, tc bit chuyn mch mi s c

thm vo.

Mt nh khai thc c th cung cp dch v cc tc bit khc nhau ( 2.5G, 10G, ... ) c lp

vi tc bit mi bc sng s dng cc tnh nng ghp knh ca thit b OTN.

Tm li

Vic s dng h thng thng tin trn nn tng SDH c truyn thng dn ht tui th, khin

cho chi ph vn hnh mng ngy cng tng cao. Vi nhiu u im nh n gin ha vic vn

hnh mng, gim thiu chi ph hot ng, mng truyn ti quang OTN thu ht c s

quan tm ca cc nh cung cp dch v. y c xem l mt phng php hiu qu p ng

nhu cu s dng ngy cng tng hin nay. Mt ro cn ln i vi vic nng cp h thng mng

c SDH hin c sang OTN l chi ph u t cn thit chuyn i ton b mng kh ln. Do

vic nng cp mng cn c thc hin tng phn mt, theo tng giai on, nhm tn dng

h tng mng c v tng bc h tr thm cc dch v mi theo yu cu ca ngi dng.

17

3. Mng truyn ti quang OTN (Optical Transport Network) theo Khuyn ngh

ITU-T G.709/Y.1331/V3

Mng truyn ti quang OTN (Optical Transport Network) ca cc nh cung cp thit b u phi

tun th theo Khuyn ngh ITU-T G.709/Y.1331. Khuyn ngh ITU-T G.709/Y.1331 nh ngha

v quy nh cc thng s k thut cho h thng phn cp truyn ti quang OTH (optical

transport hierarchy) nhm h tr vn hnh v qun l cc mt k thut ca cc mng quang c

cc kin trc khc nhau , v d nh , im-im, vng ring v kin trc li. Mc 3 trnh by

Khuyn ngh ITU-T G.709/Y.1331 theo phin bn 3 (V3).

Khuyn ngh ny nh ngha cc c im k thut cc giao din ca mng li truyn ti quang

c s dng trong v gia cc mng con ca mng quang, bao gm :

1) H thng phn cp truyn ti quang (OTH);

2) Chc nng ca cc tiu h tr cc mng quang a bc sng;

3) Cc cu trc khung;

4) Cc tc bit;

5) nh dng cho nh x cc tn hiu khch hng;

6) H tr cho mt tp hp m rng (khng gii hn) cc tn hiu khch hng tc khng

i CBR (constant bit rate client signals);

7) Mt khung tn hiu ODUk linh hot, c th c bt k t l bit v kh nng chu ng bin

ng ca tc bit ln n 100 ppm;

8) Mt th tc nh x tng qut GMP (generic mapping procedure) c lp vi tn hiu

khch hng/tn hiu my ch (server) nh x mt tn hiu ca khch hng vo ti tin

ca mt OPUk, hoc nh x mt tn hiu ODUj vo ti tin ca mt hoc nhiu khe

lung TS trong mt OPUk;

9) Kh nng o tr khung ODUk.

Cc giao din c nh ngha trong khuyn ngh ny c p dng giao din ngi s dng-

n-mng UNI (user-to-network interface) v giao din nt mng NNI (network node interface)

ca mng truyn ti quang. Khuyn ngh ny cng xc nh cc giao din c s dng trong

3.1. Gii thiu Khuyn ngh ITU-T G.709/Y.1331/V3

18

mng con quang, cc c im ca giao din ph thuc cng ngh quang v c th thay i khi

cng ngh tin trin trong cc nm k tip.

Dng tn hiu c bn ca OTN c minh ha trong Hnh 3.1. Tn hiu ca khch hng c

a vo khung vng ti tin (payload), v ghp vi cng vi mt s knh tiu , tr thnh n

v Ti tin Quang OPU(Optical Payload Unit). Mt OPU l khi nim tng ng vi mt

ng dn SDH (SDH Path). K tip tiu OAM c b sung vo OPU to ra cc n v

D liu quang ODU (Optical Data Unit), trong c chc nng tng t nh cc ng dy

(SDH Line) hay cn c gi l on Ghp SDH (SDH Multiplex Section). Tiu Truyn ti

(v d, tiu ng b khung) sau c thm vo ODU to ra mt n v Vn

chuyn(Truyn ti) Quang OTU (Optical Transport Unit). OTU l cc tn hiu k thut s c

nh dng y v chc nng tng t nh on Ti to SDH(SDH Regenerator Section).

Tip theo cc OTU c truyn i trn mt bc sng (tn hiu ca khch hng thng qua mi

quan h khung tn hiu lp OTU s c trnh by trong Hnh 3.5). Sau OTU ny c

truyn qua mt bc sng, to thnh Knh quang OCh (Optical Channel).

Mt on Ghp Quang OMS (Optical Multiplexed Section) bao gm mt nhm phn chia bc

sng ca cc knh quang OCh, cng vi mt bc sng ring bit mang mt knh gim st

quang OSC (optical supervisory channel). Knh OSC c thc hin xen/rt gia cc im truy

cp. on Truyn ti Quang (c bc n) (Optical Transport Section) bao gm mt OMS (c bc

n) v mt knh tiu (trn bc sng dnh ring) .

OTS xc nh cc thng s quang ca giao din vt l. Cc tiu OCh, OMS, v OTS cung

cp cc phng tin nh gi cht lng knh truyn ti, bao gm pht hin li v s c cho

lp . Cc tiu OCh v OTS cng cung cp mt phng tin xc minh kt ni. Cc lp

OCh, OMS, v OTS c m t trong Khuyn ngh ITU-T Rec. G.872.

Khuyn ngh G.709 nh ngha cc lp tn hiu trong h thng phn cp OTN c trnh by

trong Hnh 3.2, bao gm 2 min in v min quang. Min in bao gm cc lp tn hiu l

OPUk, ODUk, OTUk. Min quang bao gm cc lp tn hiu l OCh (Optical Channel), OMS

(Optical Multiplex Section) v OTS (Optical Transport Section).

3.2. H thng phn cp truyn ti quang (OTH)

19

Hnh 3.1: Dng tn hiu c bn ca OTN

Hnh 3.2 : H thng phn cp truyn ti quang (OTH) theo Khuyn ngh G.709

20

Phn lp chc nng ca mng OTN theo loi thit b

Xt v chc nng, s phn lp chc nng trong cng mng OTN c trnh by trong Hnh 3.3.

Hnh 3.3 : Phn lp chc nng ca mng OTN tng ng loi thit b OTN

Trong Hnh 3.3, phn lp chc nng OTS, OMS v OCh thuc min quang, OTU v ODU thuc

min in. Chc nng phn lp bao gm nh sau :

1) OTS gim st cc kt ni quang ca mt chng tuyn quang (optical span).

2) OMS gim st cc kt ni quang gia cc phn t mng NE c cc chc nng ghp

knh quang (OADM/ROADM).

3) OCh truyn ti tn hiu quang gia cc trm ti to 3R (Reamplification, Reshaping,

Retiming).

4) OTU gim st cc kt ni v in ca mt chng v in (electrical span) ca cc thit

b c cu trc Nn tng Truyn ti a dch v MSTP (MultiService Transport Platforms).

5) ODU gim st cc tn hiu ng dn khch hng ca 2 u cui (end-to-end).

Tn hiu Knh quang OCh (Optical Channel) thuc trong min quang. Ngoi tn hiu OCh cn

c cc lp trong min quang c nh ngha sn nhng chng cha c s dng hin nay l :

on truyn ti quang OTS (Optical Transport Section), on ghp quang OMS (Optical

Multiplex Section).

S phn lp chc nng ny tng ng vi cc loi thit b OTN trn mng. V vy trong Hnh

3.3 cng trnh by s tng ng cc loi thit b OTN vi phn lp chc nng ca mng OTN.

i vi tt c cc tnh nng v mc ch, hin nay h thng phn cp OTN ch c bn lp khung

tn hiu trnh by trong Hnh 3.4 sau y :

21

Hnh 3.4 : S phn cp chc nng ca tn hiu OTN hin ti

Cc tn hiu OPUk, ODUk, v OTUk to thnh cc lp tng ng thuc trong min in. Tn

hiu OCh thuc trong min quang. Cc tn hiu OPUk ng gi cc tn hiu khch hng (v d

nh tn hiu SDH). Cc tn hiu OPUk hnh thnh lp tng t nh lp ng dn (path layer)

trong h thng SDH. Theo cc tn hiu khch hng c nh x vo OPUk ti u thit b

pht, v gii nh x tr li ti u thit b thu, v cc tn hiu khch hng khng b thay i bi

thit b ca mng truyn ti trong qu trnh truyn thng.

Cc tn hiu ODUk thc hin chc nng tng t nh Tiu ng dy (Line Overhead)

trong SDH. Cc tn hiu OTUk cha FEC v thc hin cc chc nng tng t nh Tiu

on (Phn khc) (Section Overhead) trong SDH. Sau khi FEC c thm vo, tn hiu sau

c gi n mt b Ni Tip/Gii Ni tip SERDES(Serializer/ Deserializer) c chuyn

i sang min quang.

Cc nh dng cho cc khung tn hiu OTN trong min in v cc mi quan h ca tn hiu

khch hng, OPU, ODU, v OTU vi cc tiu ca chng c th hin trong Hnh 3.5. Hnh

3.5 cng cho thy s tn ti ca nhiu cp gim st kt ni b i TCM ODUk. Ch trong

Hnh 3.5, FEC c thm vo mc tn hiu OTU, l bc cui cng trc khi chuyn sang

tn hiu OCh truyn dn quang, ngha l tn hiu chuyn t min in sang min quang.

22

Hnh 3.5:Mi quan h ca cc lp tn hiu khch hng, OPU, ODU, v OTU vi cc tiu

Xt v chc nng phn lp trong lin kt gia cc mng OTN, Hnh 3.6 trnh by mt v d s

lin kt cc mng OTN vi cc phn lp khc nhau v phm vi chc nng tng i ca chng.

Mng truyn ti quang OTN theo quy nh ti ITU-T Rec. G.872 nh ngha hai lp giao din:

giao din lin min IrDI (Inter-Domain Interface) v giao din ni min IaDI (Intra-Domain

Interface).

Cc IrDI l cc giao din lin min v c xc nh l c x l ti to 3R c hai pha

ca giao din. Cc IrDI l giao din c s dng gia cc nh khai thc mng khc

nhau, v cng c th l giao din gia cc thit b t cc nh cung cp khc nhau trong

cng min ca cng mt nh khai thc mng.

V IrDI l giao din dnh cho lin kt mng (interworking), n l trng tm ca s pht

trin tiu chun ban u. IaDI l giao din ni b min c s dng trong cng mt

3.3.Cu trc giao din mng truyn ti quang (Optical transport network interface structure)

23

min ca mt nh khai thc mng. V IaDI thng nm gia cc thit b ca cng mt

nh nh cung cp thit b, cho nn n c th c cc tnh nng c quyn b sung v d

nh c mt b x l FEC mnh hn.

Hnh 3. 6 : V d v chc nng phn lp trong lin kt gia cc mng OTN

Lu trong Hnh 3.6 c s tng ng v khong ca tuyn truyn dn c gim st tng t

nh nhau ca 2 phn lp chc nng OCh v OTU, ch khc l loi tn hiu quang (OCh) v tn

hiu in (OTU).

M-un Truyn ti quang-n OTM-n (Optical Transport Module-n) l cu trc thng tin c

s dng h tr cc giao din OTN ( bao gm IrDI v IaDI). Hai cu trc OTM-n c nh

ngha:

1) Giao din OTM vi y chc nng, c k hiu l OTM-n.m;

2) Giao din OTM gim bt mt s chc nng, c k hiu l : OTM-0.m, OTM-nr.m,

OTM-0.mvn. Cc giao din OTM gim bt mt s chc nng, c xc nh vi x l

3R mi u ca giao din h tr cc lp giao din OTN lin min IrDI.

Cu trc c bn ca tn hiu OTN c th hin trong Hnh 3.7.

3.3.1 Cu trc tn hiu OTN c bn

24

Hnh 3.7 (H 6-1/G.709/Y.1331) Cu trc ca cc giao din OTN

3.3.1.1 Cu trc con knh quang (OCh substructure )

Lp knh quang theo quy nh ti ITU-T Rec. G.872 c cu trc chi tit hn na trong mng

lp h tr vic qun l mng v cc chc nng gim st theo quy nh ti ITU-T Rec. G.872:

Cc knh quang vi y chc nng OCh hoc gim chc nng OChr. OChr cung cp

kt ni mng trong sut gia cc im ti sinh 3R trong OTN;

Cc n v truyn ti knh quang tiu chun ha y OTUk hoc theo chc nng

OTUkV. OTUkV cung cp s gim st v cc iu kin tn hiu cho truyn ti gia cc

im ti sinh 3R trong OTN;

Cc n v d liu knh quang (ODUk) cung cp:

1) Gim st cc kt ni b i TC (ODUkT);

2) Gim st cc ng dn gia 2 u cui (ODUkP);

3) Tng thch vi cc tn hiu khch hng thng qua n v Ti tin Knh quang

OPUk (Optical Channel Payload Unit);

25

4) Tng thch vi cc tn hiu ODUk thng qua n v Ti tin Knh quang OPUk.

3.3.1.2 Cu trc chc nng y OTM-nm (n 1)

Cc OTM-nm (n 1) bao gm cc lp sau y :

1) Chng truyn dn quang (OTSn) ;

2) on ghp knh quang (OMSn) :

3) Knh quang y chc nng (OCh) ;

4) n v truyn ti knh quang tiu chun ha y OTUk hoc theo chc nng

OTUkV;

5) Mt hoc nhiu n v d liu knh quang (ODUk).

3.3.1.3 Cu trc gim chc nng OTM-nr.m v OTM-0.m

Cc OTM-nr.m v OTM-0.m bao gm cc lp sau y :

1) Chng vt l quang ( OPSn ) ;

2) Knh quang gim chc nng ( OChr ) ;

3) n v truyn ti knh quang tiu chun ha y OTUk hoc theo chc nng

OTUkV;


3.3.1.4 Cu trc song song OTM-0.mvn

Cc OTM-0.mvn bao gm cc lp sau y :

1) Chng vt l quang ( OPSMnk ) ;

2) n v truyn ti knh quang tiu chun ha y OTUk;


Cu trc thng tin cho cc giao din OTN c i din bi cc mi quan h gia cc b cha

tin tc (information containment) v lung thng tin. Cc mi quan h gia cc b cha tin tc

ch yu c m t trong Hnh 3.8. Cc lung thng tin c minh ha trong Hnh 3.9.

V cc mc ch gim st trong OTN, cc tn hiu OTUk/OTUkV c kt cui, bt c khi no

cc tn hiu OCh tng ng c kt cui.

3.3.2 Cu trc thng tin cho cc giao din OTN

26

Hnh 3.8 (H.6-2/G.709/Y.1331)-Mi quan h gia cc b cha tin tc OTM-nm

27

Hnh 3.9 (H.6-6/G.709/Y.1331) Cc lung thng tin trn mng OTN

28

Do thit b OTN ca VTN hin nay cha p dng OTM, cc chng sau ch trnh by chi tit

cc cu trc OPUk, ODUk, v OTUk.

Trong Hnh 3.10 (7-1A), mt tn hiu khch hng (khng c cu trc tn hiu OTN), c nh

x vo mt OPU bc thp, c k hiu l "OPU(L)". Tip theo :

Tn hiu OPU(L) c nh x vo ODU bc thp, c k hiu l "ODU(L)".

Tn hiu ODU(L) hoc l c nh x vo tn hiu OTU[V], hoc vo mt ODTU. Tn

hiu ODTU c ghp thnh mt nhm ODTU (k hiu l ODTUG). Tn hiu ODTUG

c nh x vo mt OPU bc cao, c k hiu l "OPU(H)".

Tn hiu OPU(H) c nh x vo tn hiu ODU bc cao, c k hiu l "ODU(H)". Tn

hiu ODU(H) c nh x vo OTU.

OPU(L) v OPU(H) l c cu trc khung thng tin nh nhau, nhng cha cc tn hiu

khch hng khc nhau.

Tn hiu OTU c nh x vo tn hiu knh quang OCh.

3.4. Cc nguyn tc ghp khung/ nh x v cc tc bit ca cc khung tn hiu phn cp OTN trong min in

30

Hnh 3.10 (7-1A/G.709/Y.1331) : Cu trc ghp knh v nh x cho cc tn hiu OTN min in

Xt ring v nh x trong Hnh 3.10, tn hiu khch hng hoc mt nhm n v knh d liu

quang th k (ODTUGk) c nh x vo OPUk. Tn hiu OPUk c nh x vo mt ODUk v

ODUk c nh x vo mt OTUk. Cc OTUk c nh x vo mt OCh v OCh sau c

iu ch vo mt bc sng quang ca li DWDM bng C hay L.

Mi mt OPU, ODU, hoc OTU vi tc c th c gi l mt OPUk, ODUk, hoc ODUk

cng vi k hiu k = 0, 1, 2, 3, hoc 4. Cc tc d liu c xy dng chng c th

truyn dn tn hiu khch hng SDH hiu qu.

Tc bit v dung sai ca cc tn hiu OTUk c quy nh ti Bng 3.1.

Tc bit v dung sai ca cc tn hiu ODUk c quy nh ti Bng 3.2.

Tc bit v dung sai ca OPUk v ti tin OPUk-Xv c xc nh trong Bng 3.3.

Chu k khung OTUk/ODUk/OPUk/OPUk-Xv c quy nh ti Bng 3.4.

3.4.1 nh x (Mapping)

3.4.2 Tc bit v dung lng (Bit rates and capacity) ca cc khung tn hiu phn cp OTN

31

Ch : ti tin OPUk-Xv s khng c trnh by trong ti liu ny do cha c s dng

trong thit b OTN ca VTN.

Cc chu k a khung HO OPUk ca cc khe lung TS (tributary slot) 2.5G v 1.25G c nh

ngha trong Bng 3.5.

Cc bng thng vng ti tin ODTU c quy nh trong Bng 3.6. Bng thng ph thuc vo

loi HO OPUk (k = 1,2,3,4) v cc th tc lp nh x (AMP hoc GMP). Bng thng AMP bao

gm bng thng c cung cp bi cc byte tiu NJO. Bng thng GMP c xc nh

khng bao gm byte NJO.

Tc bit v dung lng ca ODUflex (GFP) c nh ngha trong Bng 3.7.

S lng cc khe lung TS HO OPUk ca LO ODUj c tm tt trong Bng 3.8.

Bng 3.1: Cc loi v tc bit ca OTU (Bng 7-1/G.709)

Loi OTU Tc bit OTU danh nh Dung sai tc bit OUT

OTU1 255/238 2 488 320 kbit/s = 2 666 057.143 kbit/s

20 ppm OTU2 255/237 9 953 280 kbit/s = 10 709 225.316 kbit/s

OTU3 255/236 39 813 120 kbit/s = 43 018 413.559 kbit/s

OTU4 255/227 99 532 800 kbit/s = 111 809 973.568 kbit/s

Ghi ch Bng 3.1 : Trong Khuyn ngh G.709 V3 cc tn hiu OTU0, OTU2e v OTUflex cha

c xc nh. Cc tn hiu ODU0 s c vn chuyn thng qua cc tn hiu ODU1, ODU2,

ODU3 hoc ODU4; tn hiu ODU2e s c vn chuyn thng qua cc tn hiu ODU3 v

ODU4; tn hiu ODUflex c vn chuyn thng qua cc tn hiu ODU2, ODU3 v ODU4.

Bng 3.2: Cc loi v tc bit ca ODU (Bng 7-2/G.709)

Loi ODU Tc bit ODU Dung sai tc bit

ODU ODU0 1 244 160 kbit/s

20 ppm ODU1 239/238 2 488 320 kbit/s =2 498 775,126 kbit/s

ODU2 239/237 9 953 280 kbit/s =10 037 273,924 kbit/s

ODU3 239/236 39 813 120 kbit/s=40 319 218,983 kbit/s

ODU4 239/227 99 532 800 kbit/s=104 794 445,815

kbit/s ODU2e 239/237 10 312 500 kbit/s=10 399 525,316 kbit/s 100 ppm

32

ODUflex dnh

cho cc tn hiu

khch hng

CBR.

239/238 tc bit tn hiu khch hng dung sai tc bit

tn hiu khch hng

ti a l 100 ppm

ODUflex dnh

cho cc tn hiu

khch hng

c nh x

GFP-F.

Tc bit c cu hnh trong Bng 7-8/G.709.

20 ppm

Bng 3.3: Cc loi v tc bit ca OPU (Bng 7-3/G.709)

Loi OPU Tc bit ti tin OPU Dung sai tc bit ti

tin OPU OPU0 238/2391 244 160 kbit/s = 1 238 954.310 kbit/s

20 ppm OPU1 2 488 320 kbit/s = 2 488 320.000 kbit/s

OPU2 238/2379 953 280 kbit/s = 9 995 276.962 kbit/s

OPU3 238/23639 813 120 kbit/s = 40 150 519.322 kbit/s

OPU4 238/22799 532 800 kbit/s = 104 355 975.330

kbit/s OPU2e 238/23710 312 500 kbit/s = 10 356 012.658 kbit/s Dung sai tc bit tn

hiu khch hng ti a

l 100 ppm;

OPUflex

dnh cho cc

tn hiu khch

hng CBR

Tc bit tn hiu khch hng

Dung sai tc bit tn

hiu khch hng ti a

l 100 ppm

33

OPUflex

dnh cho

cc tn hiu

khch hng

c nh x

GFP-F

238/239 tc tn hiu ODUflex

20 ppm

OPU1-Xv X2 488 320 kbit/s = X2 488 320.000 kbit/s

20 ppm OPU2-Xv X238/2379 953 280 kbit/s = X9 995 276.962

kbit/s

OPU3-Xv X238/23639 813 120 kbit/s = X40150 519.322

kbit/s

Bng 3.4: Chu k ca khung OTUk / ODUk / OPUk (Bng 7-4/G.709)

Loi OTU/ODU/OPU Chu k (Period) (*)

OTU1/ODU1/OPU1/OPU1-Xv 48.971 s



Ghi ch (*) gi tr chu k c xp x lm trn vi 3 ch s c ngha.

(Ch ti tin OPUk-Xv khng c trnh by do khng s dng trong thit b OTN ca

VTN).

Bng 3.5: Thi gian chu k ca a khung HO OPUk ca khe lung TS 2.5G and 1.25G (Bng 7-6/G.709)

Loi OPU Chu k ca a khung HO

OPUk ca khe lung TS 1.25G

(*)

Chu k ca a khung HO OPUk

ca khe lung TS 2.5G (*)

OPU1 97.942 s -

OPU2 97.531 s, 48.765 s

OPU3 97.119 s 48.560 s

OPU4 93.416 s -

Ghi ch (*) gi tr chu k c xp x lm trn vi 3 ch s c ngha.

34

Bng 3.6: Bng tn ti tin ODTU kbit/s (Bng 7-7/G.709)

Loi ODTU Bng tn danh nh ca ti tin ODTU Dung sai tc bit

ca ti tin ODTU

ODTU01 (1904 + 1/8)/3824 x ODU1 bit rate

20 ppm




ODTU2.ts ts x 476/3824 x ODU2 bit rate

ODTU3.ts ts x 119/3824 x ODU3 bit rate

ODTU4.ts ts x 47.5/3824 x ODU4 bit rate

Ti thiu Danh nh Ti a

ODTU01 1 244 216.796 1 244 241.681 1 244 266.566

ODTU12 2 498 933.311 2 498 983.291 2 499 033.271

ODTU13 2 509 522.012 2 509 572.203 2 509 622.395

ODTU23 10 038 088.048 10 038 288.814 10 038 489.579

ODTU2.ts ts x 1 249 384.632 ts x 1 249 409.620 ts x 1 249 434.608



Ghi ch (*) gi tr bng thng c xp x lm trn vi 3 ch s c ngha.

Bng 3.7: Cc tc bit v dung sai ca ODUflex(GFP) (Bng 7-8/G.709)

Loi ODU Tc bit danh nh Dung sai tc bit

ODU2.ts (*) 1'249'177.230 kbit/s

ODU3.ts (*) 1'254'470.354 kbit/s

ODU4.ts (*) 1'301'467.133 kbit/s

ODUflex(GFP) c n khe lung TS: 1 n 8 n ODU2.ts 100 ppm



Ghi ch (*) Cc gi tr ca ODUk.ts c la chn cho php mt lot cc phng php c s dng to ra mt tn hiu ng h ODUflex (GFP). Xem Ph lc XI/G.709 cho bit ngun gc ca cc gi tr v cc phng php pht ng h ODUflex (GFP).

Gi tr "n" l s lng cc khe lung TS (tributary slots) b chim bi ODUflex (GFP).

35

Bng 3.8: S lng cc khe lung TS cn c ghp ODUj vo HO OPUk (Bng 7-

9/G.709)

# Khe lung

TS 2.5G

OPU2

OPU3

# Khe lung TS 1.25G

OPU1 OPU2 OPU3 OPU4 LO ODU

ODU0 1 1 1 1

ODU1 1 1 2 2 2

ODU2 4 8 8

ODU2e 9 8

ODU3 31

ODUflex(CBR)

ODUflex(IB SDR)

ODUflex(IB DDR)

ODUflex(IB QDR)

ODUflex(FC-400)

ODUflex(FC-800)

Ghi ch 1

3

5

4

7

Ghi ch 2

3

5

9

4

7

Ghi ch 3

2

4

8

4

7

ODUflex(FC-1600)

ODUflex(3G SDI) (2 970 000)

ODUflex(3G SDI) (2 970 000/1.001)

3

3

12

3

3

11

3

3

ODUflex(GFP) n n n

Ghi ch 1 S lng TS = tr lm trn trn trn (tc bit ODUflex(CBR) /(Ttc

ODTU2.ts) (1+ dung sai tc bit ODUflex(CBR))/(1 dung sai tc bit HO OPU2)).

Ghi ch 2 S lng TS = tr lm trn trn trn (tc bit ODUflex(CBR)/(T tc bit


Ghi ch 3 S lng TS = tr lm trn trn trn (tc bit ODUflex(CBR)/(T tc bit


Ghi ch 4 T l tha s chuyn m. Tham kho cc iu khon 17.7.3, 17.7.4 v

17.7.5/G709.

36

Hnh 3.10 th hin mi quan h gia cc yu t ghp knh phn chia thi gian khc nhau ca

lp tn hiu ODU s c trnh by ln lt sau y. Bng 3.9 (Table 7-10) cung cp tng quan

ca cc loi khe lung TS hp l v cc ty chn cu hnh th tc nh x.

Ti a ln n 2 tn hiu ODU0 c ghp vo mt ODTUG1(PT = 20) s dng ghp

phn chia thi gian. K tip ODTUG1(PT = 20) ny c nh x vo OPU1.

Ti a ln n 4 tn hiu ODU1 c ghp vo mt ODTUG2(PT = 20) s dng ghp

phn chia thi gian. Cc ODTUG2(PT = 20) c nh x vo OPU2.

Mt hn hp ca q (q 16) tn hiu ODU1, p (p 4) tn hiu ODU2 c th c ghp

vo mt ODTUG3(PT = 20) s dng ghp phn chia thi gian. ODTUG3(PT = 20) c

nh x vo OPU3 .

Mt hn hp ca p (p 8) tn hiu ODU0, q (q 4) tn hiu ODU1, r (r 8) tn hiu

ODUflex c th c ghp vo mt ODTUG2(PT = 21) s dng ghp phn chia thi

gian. ODTUG2(PT = 21) c nh x vo OPU2 .

Mt hn hp ca p (p 32) tn hiu ODU0, q (q 16) tn hiu ODU1, t (t 32) tn hiu

ODUflex, r (r 4) tn hiu ODU2 v s (s 3) tn hiu ODU2e c th c ghp vo mt

ODTUG3 (PT = 21) s dng ghp phn chia thi gian. ODTUG3 (PT = 21) c nh x

vo OPU3.

Mt hn hp ca p (p 80) tn hiu ODU0, q (q 40) tn hiu ODU1, u (u 80) tn hiu

ODUflex, r (r 10) tn hiu ODU2, s (s 10) tn hiu ODU2e v t (t 2) tn hiu ODU3

c th c ghp vo mt ODTUG4(PT = 21) s dng ghp phn chia thi gian.

ODTUG4(PT = 21) c nh x vo OPU4.

3.4.4 Ghp knh phn chia thi gian ODUk (Time-Division Multiplex)

37

Cc trng hp trnh by trn c tng kt trong bng sau y.

ODTUG1 ODTU2 ODTUG3 ODTUG2 ODTUG3 ODTUG4

PT=20 PT=21

ODU0 2 - - 8 32 80

ODU1 - 4 16 4 16 40

ODUflex - - - 8 32 80

ODU2 - - 4 - 4 10

ODU2e - - - - 3 10

ODU3 - - - - - 2

(Ghi ch: k hiu - l khng p dng)

Ch : ODTUGk l mt cu trc logic v khng c nh ngha chi tit hn. Cc tn hiu

ODTUjk v ODTUk.ts c ghp phn chia thi gian trc tip vo cc khe lung (Tributary

Slots) TS ca mt HO OPUk.

Bng 3.9 trnh by tng quan ca cc loi khe lung TS v cc loi nh x ODUj vo OPUk

(Table 7-10/G.709).

Bng 3.9 Cc loi nh x ODUj vo OPUk (Table 7-10/G.709)

Khe lung 2.5G Khe lung 1.25G

OPU2 OPU3 OPU1 OPU2 OPU3 OPU4

ODU0 - - AMP (PT=20)

GMP (PT=21)

GMP (PT=21)

GMP (PT=21)

ODU1 AMP (PT=20)

AMP (PT=20)

- AMP (PT=21)

AMP (PT=21)

GMP (PT=21)

ODU2 - AMP (PT=20)

- - AMP

(PT=21)

GMP

(PT=21)

ODU2e - - - - GMP (PT=21)

GMP

(PT=21)

ODU3 - - - - - GMP (PT=21)

ODUflex - - - GMP (PT=21)

GMP (PT=21)

GMP (PT=21)

38

Hnh 3.11, 3.12, 3.13 trnh by cc tn hiu khc nhau c ghp bng cch s dng cc tn hiu

ODTUG1/2/3 (PT = 20).

Hnh 3.11 (Figure 7-2/G.709/Y.1331) : Ghp 04 tn hiu ODU1 vo tn hiu OPU2 thng qua tn hiu ODTUG2 (PT = 20)

Hnh 3.11 trnh by cc bc ghp 04 tn hiu ODU1 vo tn hiu OPU2 thng qua tn hiu

ODTUG2(PT = 20). Mt tn hiu ODU1 m rng thm bng cch ghp vi tiu ng b

khung (frame alignment overhead) v tip theo l nh x khng ng b vo n v lung d

liu knh quang 1 vo 2 (k hiu l ODTU12) bng cch s dng tiu nhi AMP (k hiu l

JOH). Bn tn hiu ODTU12 c ghp knh phn chia thi gian vo nhm n v lung d

liu knh quang 2 (k hiu l ODTUG2) vi ti tin loi 20 (PT=20), sau tn hiu ny c

nh x vo OPU2.

39

Hnh 3.12 (Figure 7-3/G.709/Y.1331): Ghp knh ln n 16 tn hiu ODU1 v/hoc ln n 4 tn hiu ODU2 vo tn hiu OPU3.

Hnh 3.12 trnh by ghp knh ti a ln n 16 tn hiu ODU1 v/hoc ti a ln n 4 tn hiu

ODU2 vo tn hiu OPU3 thng qua tn hiu ODTUG3 (PT = 20). Mt tn hiu ODU1 m rng

thm bng cch ghp vi tiu ng b khung v nh x khng ng b vo n v lung d

liu knh quang 1 vo 3 (k hiu l ODTU13), bng cch s dng tiu nhi AMP (JOH). Mt

tn hiu ODU2 m rng thm bng cch ghp vi tiu ng b khung v nh x khng ng

b vo n v lung d liu knh quang 2 vo 3 (k hiu l ODTU23), bng cch s dng tiu

nhi AMP (k hiu l JOH). Cc tn hiu x ODTU23 (0 x 4) v cc tn hiu "16-4x"

ODTU13 c ghp phn chia thi gian vo nhm n v lung d liu knh quang 3

(ODTUG3) vi ti tin loi 20 (PT=20), sau tn hiu ny c nh x vo OPU3.

40

Hnh 3.13(Figure 7-4/G.709/Y.1331) Ghp 02 tn hiu ODU0 vo tn hiu OPU1 thng qua

ODTUG1 (PT = 20).

Hnh 3.13 trnh by ghp 02 tn hiu ODU0 vo tn hiu OPU1 thng qua ODTUG1 (PT = 20).

Mt tn hiu ODU2 m rng thm bng cch ghp vi tiu ng b khung v nh x khng

ng b vo n v lung d liu knh quang 0 vo 1 (k hiu l ODTU01) bng cch s dng

tiu nhi AMP (JOH). Hai tn hiu ODTU01 c ghp phn chia thi gian vo nhm n v

lung d liu knh quang 1 (ODTUG1) vi ti tin loi 20 (PT=20), sau tn hiu ny c nh

x vo OPU1.

Hnh 3.14, 3.15 v 3.16 cho thy cch cc tn hiu khc nhau c ghp bng cch s dng cc

tn hiu ODTUG2/3/4 (PT = 21).

41

Hnh 3.14 (Figure 7-5/G.709/Y.1331): Ghp ln n 8 tn hiu ODU0, v/hoc ln n 4 tn hiu ODU1 v/hoc ln n 8 tn hiu ODUflex vo tn hiu OPU2 thng qua ODTUG2 (PT = 21).

Hnh 3.14 trnh by ghp ti a ln n 8 tn hiu ODU0, v/hoc ti a ln n 4 tn hiu

ODU1 v/hoc ti a ln n 8 tn hiu ODUflex vo tn hiu OPU2 thng qua ODTUG2 (PT =

21).

Mt tn hiu ODU1 m rng thm bng cch ghp vi tiu ng b khung v nh x

khng ng b vo n v lung d liu knh quang 1 vo 2 (k hiu l ODTU12) bng

cch s dng tiu nhi AMP.

42


khng ng b vo n v lung d liu knh quang 2.1 (k hiu l ODTU2.1) bng cch

s dng tiu nhi GMP.

Mt tn hiu ODUflex m rng thm bng cch ghp vi tiu ng b khung v nh

x khng ng b vo n v lung d liu knh quang 2.ts (k hiu l ODTU2.ts) bng

cch s dng tiu nhi GMP.

Ti a ln n 4 tn hiu ODTU12, 8 tn hiu ODTU2.1, v 8 tn hiu ODTU2.ts c

ghp phn chia thi gian vo nhm n v lung d liu knh quang 2 (ODTUG2) vi ti

tin loi 21 (PT=21), sau tn hiu ny c nh x vo OPU2.

Hnh 3.15 (Figure 7-6/G.709/Y.1331): Ghp ln n 32 tn hiu ODU0 v / hoc ln n 16 tn hiu ODU1 v / hoc ln n 4 tn hiu ODU2 v /hoc ln n 3 tn hiu ODU2e v / hoc ln n 32 tn hiu ODUflex vo tn hiu OPU3 thng qua ODTUG3 (PT = 21).

43

Hnh 3.15 trnh by ghp ln n 32 tn hiu ODU0 v / hoc ln n 16 tn hiu ODU1 v /

hoc ln n 4 tn hiu ODU2 v /hoc ln n 3 tn hiu ODU2e v / hoc ln n 32 tn hiu

ODUflex vo tn hiu OPU3 thng qua ODTUG3 (PT = 21).



cch s dng tiu nhi AMP (JOH).



cch s dng tiu nhi AMP.



s dng tiu nhi GMP.

Mt tn hiu ODU2e m rng thm bng cch ghp vi tiu ng b khung v nh x


s dng tiu nhi GMP.

Mt tn hiu ODUflex c m rng thm bng cch ghp vi tiu ng b khung v

nh x khng ng b vo n v lung d liu knh quang 3.ts (k hiu l ODTU3.ts)

bng cch s dng tiu nhi GMP.

Ti a ln n 16 tn hiu ODTU13, 4 tn hiu ODTU23, 32 tn hiu ODTU3.1, 3 tn hiu

ODTU3.9 v 32 tn hiu ODTU3.ts c ghp phn chia thi gian vo n v lung d

liu knh quang 3 (ODTUG3) vi vi ti tin loi 21 (PT=21), sau tn hiu ny c

nh x vo OPU3.

44

Hnh 3.16 ((Figure 7-7/G.709/Y.1331):) Ghp ln n 80 tn hiu ODU0 v/hoc ln n 40 tn hiu ODU1 v/hoc ln n 10 tn hiu ODU2 v/hoc ln n 10 tn hiu ODU2e v/hoc ln n 2 tn hiu ODU3 v/hoc ln n 80 tn hiu ODUflex vo tn hiu OPU4 thng qua tn hiu ODTUG4 (PT = 21).

Hnh 3.16 trnh by ghp ln n 80 tn hiu ODU0 v/hoc ln n 40 tn hiu ODU1 v/hoc

ln n 10 tn hiu ODU2 v/hoc ln n 10 tn hiu ODU2e v/hoc ln n 2 tn hiu ODU3

v/hoc ln n 80 tn hiu ODUflex vo tn hiu OPU4 thng qua tn hiu ODTUG4 (PT = 21).


khng ng b vo n v lung d liu knh quang 4.1 (ODTU4.1) bng cch s dng

tiu nhi GMP.


khng ng b vo n v lung d liu knh quang 4.2 (ODTU4.2) bng cch s dng

tiu nhi GMP.

45

Mt tn hiu ODU2 c m rng thm bng cch ghp vi tiu ng b khung v

nh x khng ng b vo n v lung d liu knh quang 4.8 (ODTU4.8) bng cch s

dng tiu nhi GMP.

Mt tn hiu ODU2e m rng thm bng cch ghp vi tiu ng b khung v nh x

khng ng b vo n v lung d liu knh quang 4.8 ( ODTU4.8) bng cch s dng

tiu nhi GMP.

Mt tn hiu ODU3 c m rng thm bng cch ghp vi tiu ng b khung v

nh x khng ng b vo n v lung d liu knh quang 4.31 (ODTU4.31) bng cch

s dng tiu nhi GMP.

Mt tn hiu ODUflex c m rng thm bng cch ghp vi tiu ng b khung v

nh x khng ng b vo n v lung d liu knh quang 4.ts (ODTU4.ts) bng cch

s dng tiu nhi GMP.

Ti a ln n 80 tn hiu ODTU4.1, 40 tn hiu ODTU4.2, 10 tn hiu ODTU4.8, 2 tn

hiu ODTU4.31 v 80 tn hiu ODTU4.ts c ghp phn chia thi gian vo n v

lung d liu knh quang 4 (ODTUG4) vi vi ti tin loi 21 (PT=21), sau tn hiu

ny c nh x vo OPU4.

Hnh 3.17 trnh by v d ghp 4 tn hiu ODU1 thnh mt ODU2.

Hnh 3.17 : Ghp 4 tn hiu ODU1 thnh mt ODU2

3.4.5 Cc v d minh ho ghp knh phn chia thi gian ODUk

46

Cc tn hiu ODU1 bao gm tiu ng b khung (Frame Alignment Overhead) v ton bit 0

ti cc v tr tiu OTUk tng thch vi ng h ODU2 thng qua nhi ( nh x khng ng

b). Nhng tn hiu ODU1 c tng thch s c an xen byte vo vng ti tin OPU2, v

cc tn hiu kim sot nhi v c hi nhi ca chng (JC, NJO) c an xen khung vo vng

tiu OPU2. Tiu ODU2 c thm vo, sau ODU2 c nh x vo OTU2. Tiu

OTU2 v tiu ng b khung c thm vo hon thnh mt tn hiu dnh cho truyn ti

thng qua mt tn hiu OTM.

Hnh 3.18 trnh by trng hp ghp 2 tn hiu ODU0 thnh mt ODU1.

Hnh 3.18 : Ghp 2 tn hiu ODU0 thnh mt ODU1.

47

Cc tn hiu ODU0 bao gm tiu ng b khung (Frame Alignment Overhead) v ton bit 0

ti cc v tr tiu OTUk c thch nghi vi ng h ODU2 thng qua nhi (nh x khng

ng b). Nhng tn hiu ODU1 c thch nghi s c an xen byte vo vng ti tin

OPU1, v cc tn hiu kim sot nhi v c hi nhi ca chng (JC, NJO) c an xen khung

vo vng tiu OPU1 v tiu ODU1 c thm vo.

OCh truyn ti mt tn hiu khch hng gia cc trm ti to 3R (Khuch i-Reamplification,

Sa dng tn hiu-Reshaping, Ti nh thi tn hiu-Retiming). Cc tn hiu khch hng OCh

quy nh ti Khuyn ngh ny l nhng tn hiu OTUk.

Cu trc knh quang OCh cc chc nng c trnh by trong Hnh 3.19, gm 2 phn: tiu

OCh v ti tin OCh.

Hnh 3. 19 (Figure 10-1/G.709/Y.1331) Cu trc knh quang cc chc nng OCh

Cu trc knh quang OCh khng cc chc nng c trnh by trong Hnh 3.20, ch gm ti

tin OChr.

Hnh 3.20( Figure 10-2/G.709/Y.1331) Cu trc knh quang khng cc chc nng Ochr

3.5 Knh quang OCh (Optical channel)

3.5.1 Knh quang cc chc nng OCh

3.5.2 Knh quang OCh khng y cc chc nng (OChr)

48

OTUk[V] c iu kin ODUk, dnh vn chuyn qua mt kt ni mng knh quang. Cu trc

khung OTUk, bao gm c OTUk FEC, l hon ton chun ha.

OTUkV l mt cu trc khung, bao gm c OTUkV FEC, ch c tiu chun ha mt s chc

nng (v d, ch c chc nng c yu cu mi c quy nh); tham kho Ph lc II/G.709.

Bn cnh OTUk[V] v OTUk, cn c nh ngha mt OTUkV trong cu trc khung OTUk

tiu chun ha hon ton c kt hp vi tiu chun chc nng OTUkV FEC.

Cu trc khung OTUk (k = 1,2,3,4) c thit lp da trn cu trc khung ODUk v c m

rng vi phn Sa li thun FEC(forward error correction) nh trong Hnh 3.21.

256 ct c thm vo khung ODUk dnh cho FEC v cc byte nm trong dng 1, ct 8-14 ca

phn tiu ODUk c s dng dnh cho tiu OTUk. Nh vy, cu trc khung OTUk l

mt khi cu trc khung byte da trn vi 4 hng v 4080 ct. MSB trong mi byte l bit 1,

LSB l bit 8.

Ch : - Khuyn ngh ny khng xc nh mt cu trc khung OTUk cho k = 0, k = 2e hoc

k = flex.

Hnh 3.21 (Fig 11-1/G.709/Y.1331) Cu trc khung OTUk

Tc bit ca cc tn hiu OTUk c quy nh trong Bng 3.1 (Table 7-1).

3.6. n v truyn ti knh quang OTU (Optical channel transport unit)

3.6.1 Cu trc khung OTUk

49

Phn sa li thun FEC ca OTUk (k = 1,2,3,4) cha m FEC RS (255.239) (RS:Reed-

Solomon). S truyn i ca OTUk FEC l bt buc i vi k = 4 v ty chn cho k = 1,2,3. Nu

khng c FEC c truyn i, cc byte nhi c nh (cc bit ton 0) s c s dng.

lin kt gia cc thit b h tr FEC vi cc thit b khng h tr FEC (chn cc byte nhi c

nh cc bit ton 0 trong vng FEC ca OTUk (k = 1,2,3), cc thit b c FEC s h tr kh

nng v hiu ha qu trnh gii m FEC (ngha l b qua ni dung trong vng FEC ca OTUk (k

= 1,2,3)).

Th t truyn ca cc bit trong khung OTUk l tri sang phi, trn xung di, v MSB n

LSB (xem Hnh 3.22).

Hnh 3. 22(H 11-2/G.709/Y.1331): Th t truyn ca cc bit trong khung OTUk

Ton b khung OTUk s c a vo b ngu nhin ho. Cc byte khung (FAS) ca tiu

OTUk khng c ngu nhin ho. Ngu nhin ho c thc hin sau khi tnh ton FEC v

chn vo tn hiu OTUk.

Cu trc khung ODUk (k = 0,1,2,2 e, 3,4, flex) c th hin trong Hnh 3.23. N c t chc

trong mt cu trc khung khi byte vi 4 hng v 3824 ct.

3.6.2 Ngu nhin ho khung OTUk

3.7 n v d liu quang ODUk (Optical channel data unit)

3.7.1 Cu trc khung ODUk

50

Hnh 3.23 (Figure 12-1/G.709/Y.1331) Cu trc khung ODUk

Hai vng chnh ca khung ODUk l:

1) Vng tiu ODUk;

2) Vng OPUk.

Ct t 1 n 14 ca ODUk c dnh ring cho vng tiu ODUk.

Ch :

Ct 1 n 14 ca dng 1 c dnh ring ng b khung v tiu xc nh ca OTUk.

Ct 15-3824 ca ODUk c dnh ring cho vng OPUk.

Tn hiu ODUk c th c to ra bng cch s dng tn hiu ng h t hoc ngun ng h

ca ni b thit b, hoc tn hiu ng h c phc hi t cc tn hiu ca khch hng.

Trong trng hp sau, tn s ODUk (dung sai tn s) c kha ng b vi tn s

(dung sai tn s) tn hiu ca khch hng.

Trong trng hp trc, tn s (v dung sai tn s) ca ODUk c kha ng b vi

tn s (v dung sai tn s) ca ng h a phng.

Ngun ng h ni ca thit b c dung sai tn s cho OTN c xc nh l 20 ppm (20 phn

triu).

Cc tn hiu bo tr ODUk (ODUk AIS, OCI, LCK) c to ra bng cch s dng ngun ng

h ni ca thit b. Trong mt s trng hp ngun ng h ca ni b thit b ny c th l

ng h ca mt tn hiu bc cao hn m cc tn hiu ODUk c truyn ti gia thit b hoc

3.7.2 Tc bit v dung sai tc bit ca ODUk

51

i xuyn qua thit b (trong mt hoc nhiu khe lung TS). i vi nhng trng hp ny, t l

nhi danh ngha cn c trin khai thc hin ng tiu chun dung sai tc bit ca ODUk.

3.7.2.1 ODU0, ODU1, ODU2, ODU3, ODU4

Cc ng h ni c s dng to ra cc tn hiu ODU0, ODU1, ODU2, ODU3 v ODU4

c pht ra bi cc dao ng ng h thch anh. Cc dao ng ng h thch anh cng c

s dng cho vic to ra cc tn hiu SDH STM-N. Do cc tc bit ca cc tn hiu ODUk

(k = 0,1,2,3,4) ny c lin quan n cc tc bit STM-N v dung sai tc bit chnh l dung

sai tc bit ca cc tn hiu STM-N.

Tc bit ODU0 l 50% tc bit STM-16.

Tc bit ODU1 l bng 239/238 ln tc bit STM-16.

Tc bit ODU2 l bng 239/237 ln ca 4 ln tc bit STM-16.



Cc tn hiu ODU1, ODU2 v ODU3 mang mt tn hiu STM-N (N = 16, 64, 256) cng c th

c to ra bng cch s dng tn hiu ng h c phc hi t cc tn hiu ca khch hng.

Tham kho Bng 3.2 (Table 7-2/G.709/Y.1331) cho tc bit danh ngha v dung sai tc bit

ca ODUk.

3.7.2.2 ODU2e

Mt tn hiu ODU2e c to ra bng s dng tn hiu ng h c phc hi t cc tn

hiu ca khch hng.

Tc bit ODU2e l 239/237 ln tc bit khch hng 10GBASE-R.

Tham kho Bng 3.2(Table 7-2/G.709/Y.1331) cho tc bit danh ngha v dung sai tc bit.

3.7.2.3 ODUflex dnh cho cc tn hiu khch hng CBR

Mt tn hiu ODUflex(CBR) c to ra bng cch s dng tn hiu ng h c phc hi t

cc tn hiu ca khch hng.

Tc bit ODUflex l 239/238 ln tc bit khch hng CBR.

Tn hiu khch hng c th c dung sai tc bit ti a ln n 100 ppm.

52

Hnh 3. 24 (Fig 12-2/G.709/Y.1331) Pht tn hiu ng h ODUflex cho tn hiu CBR

3.7.2.4 ODUflex dnh cho tn hiu kim tra PRBS ( tn hiu ngu nhin) v Null

Cc kt ni ODUflex (CBR) c th c kim tra bng cch s dng mt tn hiu kim tra

PRBS hoc NULL (nh tn hiu khch hng) thay cho tn hiu khch hng CBR. i vi trng

hp ny tn hiu ODUflex (PRBS) hoc ODUflex (NULL) c to ra vi mt tn s trong

phm vi dung sai ca tn hiu ODUflex (CBR).

Nu c tn hiu ng h khch hng CBR hin din, tn hiu ODUflex (PRBS) hoc ODUflex

(NULL) c th c to ra bng cch s dng tn hiu ng h khch hng CBR, nu khng tn

hiu ODUflex (PRBS) hoc ODUflex (NULL) c to ra bng cch s dng tn hiu ng h

t ngun ng h ca ni b thit b.

3.7.2.5 ODUflex dnh cho tn hiu khch hng gi c nh x GFP-F

Tn hiu ODUflex (GFP) c to ra bng cch s dng mt tn hiu ng h t ngun ng h

ni ca thit b (Hnh 3.25). ng h ny c th l ng h trch t tn hiu HO ODUk (hoc

OTUk ), hoc mt ng h ni ca thit b m cc tn hiu ODUflex c truyn xuyn qua cc

thit b .

C th to tc bit bt k cho mt tn hiu ODUflex (GFP), tuy nhin hiu qu ti a c c

khi ODUflex(GFP) chim mt s nguyn ln khe lung TS ca ng dn HO ODUk nh nht.

53

Cc tc bit c ngh p ng tiu ch ny c quy nh trong Bng 3.7 (Table 7-

8/G.709). Ngun gc ca gi tr c th c quy nh ti Ph lc XI/G.709.

Hnh 3.25 (Fig 12-3/G.709/Y.1331) Pht tn hiu ng h ODUflex cho tn hiu khch hng gi c nh x GFP-F

Cu trc khung OPUk (k = 0,1,2,2 e, 3,4, flex) c th hin trong Hnh 3.26. N c t chc

trong mt cu trc khung l khi byte vi 4 hng v 3810 ct.

Hnh 3.26 (Fig 13-1/G.709/Y.1331) Cu trc khung OPUk

Hai vng chnh ca khung OPUk l:

3.8 n v ti tin knh quang OPUk (Optical channel payload unit)

54

Vng tiu OPUk;

Vng ti tin OPUk.

Ct 15-16 ca OPUk c dnh ring cho vng tiu OPUk.

Ct 17-3824 ca OPUk c dnh ring cho vng ti tin OPUk.

Ch : - s lng ct OPUk c ngun gc t cc ct OPUk trong khung ODUk.

Tn hiu tiu OTM c k hiu l OOS (OTM overhead signal), bao gm cc tiu OTS,

OMS v OCh. nh dng, cu trc v tc bit ca OOS khng c nh ngha trong khuyn

ngh ny. OOS c vn chuyn thng qua mt OSC.

Ty thuc vo thit k mng xp chng qun l logic ca nh khai thc, truyn thng qun l

chung cng c th c vn chuyn trong OOS. Do , OOS cho mt s ng dng cng c th

vn chuyn thng tin lin lc qun l chung. Thng tin lin lc qun l chung c th bao gm

bo hiu, thng tin lin lc bng thoi, ti phn mm, truyn thng ca nh khai thc c th, vv

Tng quan v tiu OTS, OMS v OCH c trnh by trong Hnh 3.27.

Hnh 3.27 (Fig 15-1/G.709/Y.1331) Cc thnh phn logic ca tiu OTSn, OMSn v OCh trong OOS

Thng tin tiu OTUk OH l mt phn ca cu trc tn hiu OTUk. N bao gm cc thng tin

v cc chc nng hot ng h tr vic vn chuyn tn hiu thng qua mt hoc nhiu kt ni

knh quang OCh. Cc tiu OTUk OH kt cui ti ni m khung tn hiu OTUk c to lp

v trch ra x l.

3.9 Tiu ca cc khung tn hiu mng OTN

55

Thng tin tiu OTUk, ODUk v OPUk c trnh by trong Hnh 3.28 v 3.29.

Hnh 3.28(Fig 15-2/G.709/Y.1331) Cu trc khung OTUk, ng b khung FAS v tiu OTUk

56

Hnh 3.29(Fig 15-3/G.709/Y.1331)Cu trc khung ODUk, tiu ODUk v OPUk

57

3.9.1.1 Tiu n v ti tin knh quang OPUk OH (Optical channel payload unit

overhead)

Thng tin tiu OPUk OH c thm vo ti tin OPUk to ra mt OPUk. N bao gm cc

tin tc h tr s thch ng tc cho cc tn hiu ca khch hng. Cc OPUk OH c kt

cui ti v tr OPUk c ghp/gii ghp. nh dng c th cho tiu OH v m ha c

trnh by ti mc 3.9.9.

3.9.1.2 Tiu n v d liu knh quang ODUk OH (Optical channel data unit overhead)

Thng tin tiu ODUk OH c thm vo thng tin ti tin ODUk to ra mt ODUk. N

bao gm cc thng tin v bo tr v cc chc nng hot ng h tr cc knh quang. Cc

ODUk OH bao gm nhng phn dnh ring cho cc ng dn ODUk gia 2 u cui (end-to-

end) v su cp gim st kt ni b i TCM. Cc tiu ng dn ODUk kt cui ti ni

ODUk c ghp/gii ghp. Tiu TC c thm v kt cui ti ngun v ch ca cc kt ni

TCM tng ng. nh dng tiu OH c th v m ha c trnh by ti mc 3.9.6 v 3.9.8.

3.9.1.3 Tiu n v truyn ti knh quang OTUk OH (Optical channel transport unit

overhead)

Thng tin tiu OTUk OH l mt phn ca cu trc tn hiu OTUk. N bao gm cc thng tin

v cc chc nng hot ng h tr vic vn chuyn thng qua mt hoc nhiu kt ni knh

quang. Cc tiu OTUk OH kt thc khi tn hiu OTUk c ghp/gii ghp. nh dng tiu

OH c th v m ha c trnh by ti mc 3.9.6 v 3.9.7.

Cu trc khung c th v m ha cho cc tiu OTUkV OH phi tiu chun nm ngoi phm vi

ca Khuyn ngh ny. Ch c chc nng c bn cn thit m c h tr c xc nh trong

mc 3.9.7.3.

3.9.1.4 Tiu khng lin kt n knh quang (OCh OH) (Optical channel non-associated

overhead)

Thng tin tiu OCh OH c thm vo to ra mt OCh. N bao gm cc thng tin v cc

chc nng bo tr h tr qun l li. Cc tiu OCh OH chm dt khi tn hiu OCh c

ghp v gii ghp.

3.9.1 Cc loi tiu

58

Quy nh cu trc khung c th v m ha cho OCh OH, OMS OH, OTS OH, COMMS OH

nm ngoi phm vi ca Khuyn ngh ny cho nn phn sau s khng trnh by.

Mt b nhn dng du vt TTI (Trail trace identifier) c nh ngha nh l mt chui 64-byte

vi c cu nh sau (xem Hnh 3.30):

1) TTI [0] cha k t SAPI [0] c tr c nh l tt c cc bit 0.

2) TTI [1] n TTI [15] cha 15 k t nhn dng im truy cp ngun (SAPI [1] n

SAPI [15]).

3) TTI [16] cha cc k t DAPI [0] c tr c nh l tt c cc bit 0.

4) TTI [17] n TTI [31] cha 15 k t nhn dng im truy cp ch n (DAPI [1]

n DAPI [15]).

5) TTI [32] n TTI [63] xc nh nh khai thc c th.

Hnh 3.30 (Fig 15-4/G.709/Y.1331) Cu trc TTI

3.9.2 Nhn dng du vt v nh ngha nh danh im truy cp (Trail trace identifier and access point identifier definition)

59

Cc tnh nng ca b (nhn dng) nh im truy cp API (Access Point Identifiers) l:

1) Mi b nhn dng im truy nhp phi duy nht trn ton cc trong lp mng ca n.

Trng hp d kin l cc im truy cp c th c yu cu cho vic thit lp ng dn

trn mt ranh gii gia cc nh khai thc, b nhn dng im truy cp phi c sn cho cc

nh khai thc mng khc .

2) B nhn dng im truy cp khng nn thay i trong khi im truy cp vn cn tn ti.

3) B nhn dng im truy cp nn c th xc nh cc quc gia v nh khai thc mng c

trch nhim nh tuyn i n v ri khi cc im truy cp .

4) Vic thit lp tt c cc b nhn dng im truy cp thuc v mt lp mng hnh chnh

duy nht nn to thnh mt chng trnh xc nh im truy cp duy nht.

5) Th tc thit lp b nhn dng im truy cp cho mi mng lp qun tr c th c lp

i vi mng qun tr khc nhau.

Cc ODUk , OTUk v OTM c chng trnh xc nh im truy cp da trn mt nh dng cu

trc cy h tr cc thut ton tm kim iu khin nh tuyn. X l nhn dng im truy cp

c yu cu r rng trn ton cc.

B nhn dng im truy cp (SAPI , DAPI) bao gm mt phn khc quc t 3 k t v phn

khc quc gia NS (national segment) 12 k t c trnh by trong Hnh 3.31.

Hnh 3.31 (Fig 15-5/G.709/Y.1331) Cu trc nh danh im truy cp

Cc k t nh danh im truy cp trong Hnh 3.31 c m ha theo ITU- T Rec. T.50 ( tham

kho Bng ch ci quc t - b k t m ha 7-bit trao i thng tin ) ln lt l :

60

1) Trng phn khc quc t cung cp mt m 3 k t (ISO 3166) nh danh m quc

gia a l /chnh tr k hiu l G/PCC (Geographic/Political Country Code). M quc gia

phi da trn m 3 k t ISO 3166 vit hoa ch ci quc gia (v d, USA, FRA).

2) Trng phn khc quc gia bao gm hai trng con l : m nh cung cp dch v ITU

ICC(ITU carrier code) tip theo l mt m im truy cp duy nht UAPC(unique access

point code).

M nh cung cp dch v ITU ICC l mt m gn cho mt nh khai thc mng/nh cung

cp dch v, c duy tr bi T chc Tiu chun ho Vin thng ITU-T TSB

(Telecommunication Standardization Bureau) theo ITU-T Rec. M.1400. M ny s bao

gm 1-6 k t, ch ci, dn u ch ci l con s.

M im truy cp duy nht UAPC l mt vn cho cc t chc m cc m quc gia v

m nh cung cp dch v ITU c ch nh, nu m bo iu kin duy nht. M ny

s bao gm 6-11 k t, vi du NUL, hon thnh phn khc quc gia 12 k t.

3.9.3.1 V tr tiu ng b khung OTUk / ODUk

V tr tiu ng b khung OTUk/ODUk c trnh by trong Hnh 9.6. Tiu ng b

khung OTUk/ODUk c p dng cho c 2 tn hiu OTUk v ODUk.

Hnh 3. 32(Fig 15-6/G.709/Y.1331) Tiu ng b khung OTUk/ODUk

3.9.3.2 nh ngha tiu ng b khung OTUk/ODUk

3.9.3.2.1 Tn hiu ng b khung FAS (Frame alignment signal)

Mt tn hiu OTUk-FAS c 6 byte (xem Hnh 3.33) c nh ngha trong hng 1, ct t 1 n

6 ca tiu OTUk. OA1 l "1111 0110". OA2 l "0010 1000".

3.9.3 Tiu ng b khung OTUk/ODUk (OTUk/ODUk frame alignment overhead)

61

Hnh 3.33(Fig 15-7/G.709/Y.1331) Cu trc tiu tn hiu ng b khung

3.9.3.2.2 Tn hiu ng b a khung MFAS (Multiframe alignment signal)

Mt s tn hiu OTUk v cc tn hiu tiu ODUk dn tri trn nhiu khung OTUk/ODUk,

hnh thnh a khung bao gm 256 khung. V d nh cc tn hiu TTI v tiu TCM-ACT. Cc

tn hiu ny v cc tn hiu tiu c cu trc a khung khc yu cu phi x l ng b a

khung, ngoi ng b khung OTUk/ODUk.

Byte tn hiu ng b a khung duy nht (MFAS) c nh ngha trong dng 1, ct 7 ca tiu

OTUk/ODUk s dnh cho mc ch ny (xem Hnh 3.34). Gi tr ca byte MFAS s c

tng ln theo mi khung OTUk/ODUk trong mt a khung gm 256 khung.

Hnh 3.34(Fig 15-8/G.709/Y.1331) Tiu tn hiu ng b a khung

62

Cc tn hiu tiu OTUk/ODUk c th s dng a khung trung tm ny kha ng b

khung 2, khung 4, khung 8, khung 16, khung 32, v..v ca a khung vo khung chnh.

Ch : - a khung HO OPU4 80 khung khng th c h tr. Thay vo , mt Ch s a

khung OPU4 k hiu l OMFI (OPU4 Multi- Frame Indicator) gm 80 khung c s dng

thay th.

3.9.4.1 V tr ca tiu OTUk OH

V tr tiu OTUk trnh by trong cc Hnh 3.35 v 3.36.

Hnh 3.35(Fig 15-9/G.709/Y.1331) Tiu OTUk

Hnh 3.36(Fig 15-10/G.709/Y.1331) Tiu gim st on OTUk

3.9.4 Tiu OTUk OH

63

3.9.4.2 nh ngha tiu OTUk

3.9.4.2.1 Tiu gim st on SM (section monitoring ) OTUk

Mt trng ca tiu gim st on SM (section monitoring ) OTUk c nh ngha trong

hng 1, t ct 8 n 10 h tr gim st on SM.

Trng SM bao gm cc trng con sau y (xem Hnh 3.36):

1) B nhn dng du vt TTI;

2) Kim tra chn l an xen 8 bit BIP-8;

3) Ch th phn hi s c BDI ( backward defect indication);

4) Ch th phn hi li BEI (backward error indication ) v ch th phn hi li ng b tn

hiu n BIAE ( backward incoming alignment error);

5) Ch th li ng b tn hiu n IAE (incoming alignment error);

6) Cc bit dnh cho chun ho quc t tng lai RES (bits reserved for future international

standardization).

3.9.4.2.1.1 B nhn dng du vt TTI ca OTUk SM

gim st on, tiu nhn dng du vt TTI ch c 1 byte c nh ngha truyn ti cc

tn hiu TTI c 64-byte trnh by ti mc 3.9.2.

Tn hiu TTI 64-byte c ng b vi a khung OTUk (xem 3.9.6.2.2) v truyn 4 ln cho mi

a khung. Byte 0 ca tn hiu TTI 64-byte phi c mt ti cc v tr 0000 0000 (0x00), 0100

0000 (0x40), 1000 0000 (0x80) v 1100 0000 (0xC0) ca a khung OTUk.

3.9.4.2.1.2 M tch li BIP-8 ca OTUk SM

gim st on, tn hiu m tch li 1 byte c nh ngha. Byte ny chnh l m kim tra

chn l an xen 8 bit BIP-8.

Cc OTUk BIP-8 c tnh ton trn c s cc bit trong vng OPUk (ct 15-3824) ca khung

OTUk th i, v chn vo v tr tiu BIP-8 trong khung OTUk th i +2 (xem Hnh 3.37).

64

Hnh 3.37(Fig 15-11/G.709/Y.1331) Tnh ton BIP-8 ca OTUk SM

3.9.4.2.1.3 Ch th phn hi s c BDI( backward defect indication) ca OTUk SM

gim st on, tn hiu ch th phn hi s c BDI ch c 1 bit c nh ngha. BDI truyn

ti trng thi b s c ca tn hiu c tch ra trong khi chc nng kt cui on (Section

Terminating Sink Function) ca phn thu, pht i theo hng v ngun pht tn hiu.

BDI c thit lp gi tr "1" ch th phn hi c s c trn OTUk; ngc li, n c thit

lp tr "0".

3.9.4.2.1.4 Ch th phn hi li BEI (backward error indication) v ch th phn hi li ng b

tn hiu n BIAE ( backward incoming alignment error) ca OTUk SM

gim st on, tn hiu ch th phn hi li BEI v tn hiu ch th li ng b tn hiu n

BIAE gm 4 bit c nh ngha. Tn hiu ny c s dng truyn theo hng v pha pht

s lng khi xen k -bit c pht hin c li BIP-8, bi b phn gim st on OTUk ca

pha thu, bng cch s dng m BIP-8. BIAE cng c s dng truyn theo hng v pha

pht rng l c mt ch th li ng b ca tn hiu n IAE ( t trong vng tiu IAE)

c pht hin bi b phn gim st on OTUk ca pha thu.

65

Trong iu kin c xut hin ch th li ng b ca tn hiu n IAE, m " 1011 " c a vo

trng BEI/BIAE v s lng li tnh s c b qua. Nu khng, s li tnh ( t 0 n 8 ) c

a vo trng BEI/BIAE. 6 gi tr cn li biu din bi 4 bit c hiu l khng c li (xem

Bng 3.10 ) v BIAE khng hot ng.

Bng 3.10 (Table 15-1/G.709/Y.1331) Ch th BEI/BIAE ca OTUk SM

BEI/BIAE ca OTUk SM

Bits 1 2 3 4

Tn hiu BIAE S li BIP-8

(BIP violations)

0 0 0 0 False 0

0 0 0 1 False 1

0 0 1 0 False 2

0 0 1 1 False 3

0 1 0 0 False 4

0 1 0 1 False 5

0 1 1 0 False 6

0 1 1 1 False 7

1 0 0 0 False 8

1 0 0 1, 1 0 1 0 False 0

1 0 1 1 True 0

1 1 0 0 n

1 1 1 1

False 0

Ghi ch : - false : tn hiu BIAE ch th c s c

- true : tn hiu BIAE ch th khng c s c

3.9.4.2.1.5 Ch th li ng b trn tn hiu n IAE (incoming alignment error) ca OTUk SM

Tn hiu ch th li ng b tn hiu n IAE ch c 1 bit, c xc nh cho php cc nt

mng n (ingress point) ca S-CMEP thng bo cho cc nt mng ra ngang hng (peer egress

point) ca S-CMEP bit l pht hin c c mt li ng b khung (v d mt li trt bit

slip) c pht hin trn tn hiu n nt mng pha pht.

IAE c thit lp tr "1" ch ra c mt li ng b tn hiu n; nu khng c li n c

thit lp tr "0".

Nt mng n (ingress point) ca S-CMEP(egress point) s dng thng tin ny ngng tnh bit

li do mt s thay i pha khung OTUk ti nt mng n ca on.

66

3.9.4.2.1.6 Tiu dnh ring RES (reserved overhead) ca OTUk SM

gim st on, 2 bit dnh ring RES cho tng lai c thit lp tr 00.

3.9.4.2.2 Knh thng tin chung 0 l GCC0 (general communication channel 0) ca OTUk

2 byte t trong tiu OTUk h tr mt knh thng tin lin lc chung GCC0 gia cc im

kt cui OTUk. Cc byte ca GCC0 c t ti hng 1, ct 11 v 12 ca tiu OTUk. nh

ngha cho GCC0 nm ngoi phm vi ca Khuyn ngh ny.

3.9.4.2.3 OTUk reserved overhead (RES)

2 byte ca tiu OTUk c dnh ring cho tiu chun ha quc t trong tng lai. 2 byte ny

c t ti hng 1, ct 13 v 14. Cc byte c thit lp tt c l bit 0.

3.9.4.3 Tiu ca OTUkV (OTUkV OH )

Khung OTUkV c chun ho chc nng cn h tr, nh mt kh nng ti thiu, chc nng

gim st on c th so snh vi gim st on OTUk (xem 3.9.7.2.1) nh mt b TTI theo quy

nh ti mc 3.9.2. nh ngha cho tiu OTUkV nm ngoi phm vi ca Khuyn ngh ny.

3.9.5.1 V tr ca ODUk OH

V tr tiu ODUk c hin th trong Hnh 3.38 v 3.39.

Hnh 3.38: Tiu ODUk (Hnh 15-12/G.709)

3.9.5 Tiu ca ODUk ( ODUk OH )

67

a) Tiu gim st ng dn ODUk (Hnh 15-13/G.709)

b) Tiu th #i gim st kt ni b i ODUk (Hnh 15-14/G.709)

Hnh 3.39 : Tiu gim st ng dn v gim st kt ni b i ODUk

68

3.9.5.2 nh ngha tiu ODUk OH ca ODUk

3.9.5.2.1 Tiu gim st ng dn PM (path monitoring) ca ODUk

Trng tiu gim st ng dn PM ca ODUk c xc nh trong hng 3, cc ct t 10

n 12 h tr gim st ng dn v mt bit b sung gim st ng dn c nh ngha

trong bit 7 ca dng 2, ct 3.

Trng tiu gim st ng dn PM cha cc trng con sau (xem Hnh 3.40 a)):



3) Ch th phn hi s c BDI( backward defect indication);

4) Ch th phn hi li BEI (backward error indication);

5) Ch th c li ng b ca tn hiu n IAE (incoming alignment error);

6) Cc bit trng thi ch th s hin din ca mt tn hiu bo tr STAT.

Trng PM & TCM c cha cc trng con PM sau y (xem Hnh 3.38) l: s o tr ng

dn DMp (path delay measurement).

Ni dung ca trng PM, ngoi tr trng con STAT, s khng c nh ngha (c nh dng

tt c l bit 1, lp i lp li ca chui bit 0110 0110 hoc 0101 0101 ) khi c s hin din ca

mt tn hiu bo tr (v d, ODUk-AIS, ODUk-OCI, ODUk-LCK). Ni dung ca trng PM &

TCM s khng c nh ngha (nh dng tt c l bit 1, lp i lp li ca chui bit 0110 0110

hoc 0101 0101) khi c s hin din ca mt tn hiu bo tr.

3.9.5.2.1.1 B nhn dng du vt PM TTI ca ODUk

gim st on, tiu nhn dng du vt TTI ch c 1 byte c nh ngha truyn ti cc

tn hiu TTI c 64-byte quy nh ti mc 3.9.2.

Tn hiu TTI 64-byte c ng b vi a khung ODUk (xem 3.9.5.2.2) v truyn 4 ln cho mi

a khung. Byte 0 ca tn hiu TTI 64-byte phi c mt ti cc v tr 0000 0000 (0x00), 0100

0000 (0x40), 1000 0000 (0x80) v 1100 0000 (0xC0) ca a khung ODUk.

3.9.5.2.1.2 M tch li PM ca ODUk PM (BIP-8)

gim st ng dn (path), tn hiu m tch li 1 byte c nh ngha. Byte ny chnh l m

kim tra chn l an xen 8 bit BIP-8.

69

Mi BIP-8 ca ODUk PM c tnh ton trn c s cc bit trong vng OPUk (ct 15-3824) ca

khung ODUk th i, v c chn vo v tr tiu BIP-8 ca ODUk PM trong khung ODUk th

i +2 (xem Hnh 3.40).

Hnh 3.40 (Fig 15-15/G.709/Y.1331) Tnh ton BIP-8 ca ODUk PM

3.9.5.2.1.3 Ch th phn hi s c BDI ( backward defect indication) ca ODUk PM

gim st ng dn, tn hiu ch th phn hi s c BDI ch c 1 bit c nh ngha. BDI

truyn ti trng thi s c ca tn hiu c tch ra trong khi chc nng kt cui on (Section

Terminating Sink Function) ca phn thu, pht i theo hng v ngun pht tn hiu.

BDI c thit lp gi tr "1" ch th phn hi c s c trn ODUk; ngc li, n c thit

lp tr "0".

3.9.5.2.1.4 Ch th phn hi li BEI (backward error indication) ca ODUk PM

gim st ng dn, tn hiu ch th phn hi li BEI gm 4 bit c nh ngha, truyn

theo hng v pha pht s lng khi xen k -bit c pht hin c li BIP-8, bi b phn

gim st ng dn ODUk ca pha thu, bng cch s dng m BIP-8. S m ny c 9 gi tr ,

70

c th l t 0 n 8 li. 7 gi tr cn li c biu din bi 4 bit c hiu l khng c li (xem

Bng 3.11 ).

Bng 3.11(Table 15-2/G.709/Y.1331): Ch th BEI ca ODUk PM

Ch th BEI ca ODUk

PM Bit 1234

Cc li BIP-8

0000 0

0001 1

010 2

0011 3

0100 4

0101 5

0110 6

0111 7

1000 8

1001 n 1111 0

3.9.5.2.1.5 Ch th trng thi STAT ca ODUk PM

gim st ng dn, cc bit trng thi STAT c nh ngha gm 3 bit. STAT ch th s

hin din ca mt tn hiu bo tr (xem Bng 3.12).

P-CMEP thit lp cc bit STAT l "001".

Bng 3.12 : ngha ch th trng thi STAT ca ODUk PM (Bng 15-3/G.709)

Byte PM 3,

Cc bits 678

Trng thi

000 c dnh cho chun ho quc t trong tng lai

001 Tn hiu ng dn bnh thng




101 Tn hiu bo tr: ODUk-LCK

110 Tn hiu bo tr: ODUk-OCI

111 Tn hiu bo tr: ODUk-AIS

71

3.9.5.2.1.6 Ch th o tr DMp (delay measurement) ca ODUk PM

gim st ng dn ODUk, tn hiu o tr DMp ch c 1 bit c nh ngha, truyn

s bt u ca th nghim o lng tr.

Tn hiu DMp bao gm mt gi tr khng i (0 hoc 1) c o ngc lc bt u mt php

o lng tr theo 2 chiu. Vic chuyn i t 0 -> 1 trong chui ... 0000011111 ..., hoc

chuyn i t 1 -> 0 trong chui ... 1111100000 ... l biu hin thi im bt u o tr. Gi

tr mi ca tn hiu DMp c duy tr cho n khi bt u php o tr tip theo.

Tn hiu DMp ny c chn vo bi P-CMEP ngun pht i DMp v gi n P-CMEP u xa.

P- CMEP u xa s u vng ngc li tn hiu DMp v pha P-CMEP ngun pht. P-CMEP

ngun pht o s lng chu k khung gia thi im gi tr tn hiu DMP c o ngc v

thi im gi tr tn hiu DMp o ngc ny nhn c tr li t P-CMEP u xa.

Thit b thu kim tra lin tc cc tn hiu DMp nhn c. Cc khung b sung c s dng

kim tra lin tc cc tn hiu DMP khng c thm vo s khung tnh tr. Vng lp P-

CMEP lp li vic u vng mi ln nhn c bit DMp xy ra trong khong thi gian khong

100 s.

Tham kho Khuyn ngh G.798 v thng s k thut qu trnh o th trnh by trn.

Ch thch 1 - o tr ng dn c th c thc hin theo yu cu cung cp tc thi

trng thi tr truyn theo 2 chiu , v ch ng , cung cp 15 pht n 24 gi cc kt qa ghi

nhn tr truyn dn theo 2 chiu.

Ch thch 2 - Thit b c thit k nm 2008 hoc phin bn trc ca Khuyn ngh G.709

c th khng c kh nng h tr gim st tr ng dn. Trong cc thit b nh vy, cc bit

DMp thit lp v bit 0.

3.9.5.2.2 Tiu gim st kt ni b i TCM (tandem connection monitoring) ca ODUk

6 trng ca tiu gim st kt ni b i TCM ca ODUk c nh ngha trong dng 2, t

ct 5 n 13 v hng 3, t ct 1 n ct 9 ca tiu ODUk v 6 bit b sung cho TCM c

nh ngha trong bit 1-6 ca dng 2, ct 3. Kt ni b i TCM cng h tr gim st cc kt ni

ODUk (G.709 c hoc khng c FEC) cho mt hoc nhiu cc ng dng mng sau y (tham

kho thm ITU-T G.805 v ITU-T G.872):

72

1) Gim st kt ni b i quang UNI n UNI: gim st cc kt ni ODUk thng qua mng

truyn ti cng cng (t u cui i vo ca mng cng cng n u cui i ra khi

mng);

2) Gim st kt ni b i quang NNI n NNI: gim st cc kt ni ODUk thng qua mng

ca mt nh khai thc mng (t u cui i vo ca nh khai thc mng n u cui i

ra khi mng);

3) Gim st lp con cho chuyn mch bo v kt ni mng con knh quang thuc cc loi

tuyn tnh 1 +1, 1:1 v 1: n, xc nh cc iu kin tn hiu b mt v tn hiu suy gim

cht lng;

4) Gim st lp con cho chuyn mch bo v chia s vng bo v knh quang

SPRing(shared protection ring), xc nh cc iu kin tn hiu b mt v tn hiu suy

gim cht lng;

5) Gim st kt ni b i knh quang vi mc ch pht hin mt tn hiu b mt hay suy

gim cht lng trong mt kt ni knh quang b chuyn mch, bt u phc hi t

ng kt ni trong iu kin li v s c xy ra trong mng;

6) Gim st kt ni b i knh quang cho v d nh nh v li hoc xc nh cht lng

dch v.

6 trng TCM c nh s l TCM1, TCM2, ..., TCM6. Mi trng TCM cha cc trng

con sau (xem Hnh 3.41) :



3) Ch th phn hi s c BDI( backward defect indication);

4) Ch th phn hi li v ch th phn hi li ng b tn hiu n BEI/BIAE (backward error

indication and backward incoming alignment error);

5) Cc bit trng thi ch th s hin din ca tiu TCM, li ng b tn hiu n hoc mt

tn hiu bo tr ( STAT).

Mi trng PM&TCM c cha cc trng con sau (xem Hnh 3.39 ) l : trng con o tr

kt ni b i ( DMti , i = 1-6 ) .

73

Ni dung ca cc trng TCM, ngoi tr trng con STAT, s khng xc nh (nh dng tt c

l bit 1s , hoc lp i lp li 0110 0110 hoc 0101 0101) khi c s hin din ca mt tn hiu bo

tr (v d , ODUk - AIS , ODUk - OCI, ODUk - LCK ). Ni dung ca trng PM & TCM s

khng xc nh (nh dng tt c l bit 1s , hoc lp i lp li 0110 0110 hoc 0101 0101 lp i

lp li ) trong s hin din ca mt tn hiu bo tr.

Mt trng TCM v bit PM & TCM c gn cho mt kt ni c gim st nh m t trong

3.9.8.2.2.6. S lng kt ni c gim st dc theo mt ng ODUk c th thay i gia 0 v

6. Nhng kt ni c gim st ny c th c lng vo nhau , ni tip hoc c hai. Cu hnh

lng vo nhau v ni tip l cc cu hnh hot ng mc nh. Cu hnh chng cho l mt cu

hnh b sung ch cho mc ch th nghim.

Hnh 3.41 trnh by trng kt ni b i TCM c gn vo kt ni theo ng truyn dn ca

tn hiu ODUk ang c gim st. S lng kt ni b i TCM c gim st dc theo mt

ng ODUk (trail) c th thay i t 0 n 6. Cc kt ni b i TCM c gim st c th

c lng vo nhau, chng cho v / hoc ni lin tip (cascaded), c th hin trong Hnh

3.41. C th cc kt ni b i TCM A1-A2/B1-B2/C1-C2 v A1-A2/B3-B4 c lng nhau,

trong khi cc kt ni b i TCM B1-B2/B3-B4 c ni lin tip.

Hnh 3.41(Hnh 15-16/G.709/Y.1331)- V d cc kt ni gim st ca ODUk kiu ni tip v lng nhau.

74

Kt ni chng cho th hin trong Hnh 3.42 ( B1- B2 v C1- C2) .

Hnh 3.42(Hnh 15-17/G.709/Y.1331)- V d cc kt ni gim st ca ODUk kiu chng cho.

3.9.5.2.2.1 B nhn dng du vt TTI ca ODUk TCM

i vi mi trng gim st kt ni b i ca tiu ch c 1 byte c nh ngha, truyn

ti cc tn hiu TTI gm 64-byte quy nh ti mc 9.2.

Tn hiu TTI 64-byte c ng b vi a khung ODUk (xem 9.6.2.2) v truyn 4 ln cho mi

a khung. Byte 0 ca tn hiu TTI 64-byte phi c mt ti cc v tr ca a khung ODUk l 0000

0000 (0x00), 0100 0000 (0x40), 1000 0000 (0x80) v 1100 0000 (0xC0).

3.9.5.2.2.2 M tch li ca (BIP-8) ODUk TCM (error detection code)

i vi mi trng gim st kt ni b i TCM, tn hiu m tch li 1 byte c nh ngha.

Byte ny chnh l m kim tra chn l an xen 8-bit BIP-8.

Mi BIP-8 ca ODUk TCM c tnh ton trn c s cc bit trong vng OPUk (ct 15-3824)

ca khung ODUk th i, v c chn vo v tr tiu BIP-8 ca ODUk TCM trong khung

ODUk th i +2 (xem Hnh 3.43).

75

Hnh 3.43(Fig 15-18/G.709/Y.1331) Tnh ton BIP-8 ca ODUk TCM

3.9.5.2.2.3 Ch th phn hi s c BDI (backward defect indication) ca ODUk TCM

i vi mi trng gim st kt ni b i TCM, tn hiu ch th phn hi s c BDI ch c 1 bit

c nh ngha. BDI truyn ti trng thi s c ca tn hiu c tch ra trong khi chc nng

kt cui kt ni b i (a tandem connection termination sink function) ca phn thu, pht i

theo hng v ngun pht tn hiu.

BDI c thit lp gi tr "1" ch th phn hi

1-Tai Lieu OTN

Documents

Transcript of 1-Tai Lieu OTN