9:45am-I0:00am
TuC4
C oss
-
Connec ion Managemen Specialisa ion
o
WDM
-
OTN's
Albe Ra el (l), Josep P a , Jaume Comellas, and Gab iel Junyen
Poly echnical Uni e si y
o
Ca alonia (UPC), Campus No d D4-SlO8, Jo di Gi ona 1-3,
08034 Ba celona, Spain.
Tel./Fax :+34 93 401 6441/+34 93 401 7200. (1) E-mail add ess: [email p o ec ed]
1.
In oduc ion
Fu u e WDM Op ical T anspo Ne wo ks (WDM-OTN) will use new all-op ical nodes ha will pe o m unc ions such
as
ou ing, es o a ion and p o ec ion di ec ly in he op ical domain, using wa eleng h as a new ne wo k esou ce. They will
equi e new le els o managemen and supe ision
o
ensu e i s p ope ope a ion and he quali y o payload deli e y. A key
wo d in u u e Om's is e olu ion, bo h in e ms
o
a ic g ow h and echnology a ailabili y. Hence, ne wo ks' opology
and nodes' a chi ec u e will need ca e ul design in o de o mee ope a o 's equi emen s ega ding adap abili y, scalabili y,
modula i y and anspa ency. Se e al Eu opean unded p ojec s such as MEPHISTO and MOON ha e add essed he needs
o
OTN Managemen Sys ems Suppo , p oposing laye ed managemen objec in o ma ion models
o
s anda disa ion
[
11,
[2].
This pape p esen s a new app oach o he Op ical C oss-connec (OXC) ou ing ope a ion ha akes in o accoun a
diminished connec ion capabili y.
2. New class de ini ion
Connec ion capabili y o an OXC may be diminished mainly o h ee easons. The m one is ex e nal o he OXC and
comes om he impossibili y o ce ain ou pu op ical
links
o ca y speci ic clien signals due o e.g.
PMD.
The second
eason is in e nal and a ises om a componen 's ailu e hus p ecluding a numbe
o
connec ions. The hi d eason
is
also
in e nal and esul s om he connec ion na u e
o
he OXC s uc u e, which is no s ic ly non-blocking (s ic ly non-
blocking means ha an inpu channel can always each any ou pu channel).
When manag ng an OXC wi h diminished connec ion
capabili y, a ainable ou pu po s depend on bo h he numbe
and he way he exis ing connec ions ha e been es ablished.
Hence an upda ed lis wi h idle/a ailable connec ions
be ween inpu lou pu po s becomes necessa y, which can be
ep esen ed in a ma ix o ma , and shall be called Node
S a us Ma ix (NSM) om whe e he
eal
in e nal OXC
capabili ies can
be
clea ly and easily seen. Figu e
1
shows an
example whe e wo connec ions ha e been es ablished in a
4x4 OXC wi h
4
channels pe ib e. The i s sub-index
indica es he inpu ib e and he second he inpu wa eleng h
numbe . The NSM depic ed in Figu e
1
shows a connec ion
be ween
h3,2
+
I,,
p ecluding any connec ion be ween
h3.1,
h3,3,
h3.4
-+
h1.3, h3.1,
h4.2.
An
analogous case is shown
o
connec ion be ween
h4.3
-+
To manage
his
ma ix
we p opose a specialisa ion o he c oss-connec ion agmen
new class is de i ed om he gene ic objec class ubn'cR1, which i sel de i es omjbbn'c.
3.
OXC
ou ing unc ional desc ip ion
Rela ion be ween inpu lou pu channels can be desc ibed h ough he Wa eleng h T ans e Ma ix (WTM)
[4].
The
knowledge o he WTM allows he sys ema ic and simple esolu ion o he con ols and hei ope a ion
o
es ablish any
connec ion. The lis
o
hese con ols can be w i en
in
a ma ix o ma , which we
call
Rou ing Con ol Ma ix (RCM). I is
a chi ec u e depexiden showing all physical pa hs ?om any inpu o any ou pu po . Since he e may exis mo e han one
pa h be ween inpu lou pu po s, each RCM elemen is a ec o e e y elemen o which is one ou
o
n
possible ou ing pa hs
be ween inpu and ou pu (i.e.
[PI,
P2,
. . .
,
Pn]).
In gene al, he dimension o all ec o s in he RCM will be he same.
Howe e , he e a e cases whe e he OXC a chi ec u e may no
be
symme ic o e e y inpu channel and hus ec o
dimensions migh be di e en .
The ne wo k node agen uses he RCM
o
e icien ly pe o m dynamic ou ing, connec ion ea angemen , and Node S a us
Ma ix
(NSM)
upda es. NSM is an abs ac ion o he RCM and, while he la e is implemen a ion dependen , he NSM is
implemen a ion independen .
4.
Example
o
RCM
and
NSM
usage
The OXC s uc u e depic ed in Figu e
2
is
link modula whe e he
ou ing
mechanism consis s
o
Wa eleng h Con e e s
(W-C) ollowed by A ayed Wa eguide G a ings (AWG). n e en modules a e hen in e connec ed h ough S a Couple s
(SC)
o
he
ou pu
ib es.
This
s uc u e is ea angeably non-blocking, (i.e. any connec ion can be es ablished e-con igu ing
0-7803-5947-xl00/$10.0002000
IEEE
167
p e-es abiished connec ions), he e o e some connec ion eques s may be ejec ed because p e-es ablished connec ions
canno be in e up ed unless o p o ec ion pu poses.
Connec ion eques s
a e
conside ed success ully es ablished when he inpu channel can be ou ed
o
he eques ed ou pu
ib e no ma e a which wa eleng h. Blocking p obabili y is de ined
as
he a io be ween ejec ed and
o al
eques s.
To
demons a e he usage and show he use ulness o he RCM and NSM, we e alua e he blocking p obabili y
as
a unc ion o
ac i e channels. We will compa e he blocking p obabili y applying wo di e en ou ing algo i hms. The inpu a ic is
conside ed uni o mly dis ibu ed.
100
so.
-
Bbcking
(Random)
-B&hing
(EM
sl a egy)
-To al
Blocldng
(R”)
-To al
Blockhg
(ESM
s -)
so.
20-
40
w)
60
m
so
m
im
k iw
Channels
(n)
Figu e
3.
Block p obabili y using wo ou ing app oaches.
Figu e 2.4~4 OXC a ch. wi h
8
wa eleng hs pe ib e.
To simula e he OXC ope a ion, we andomly gene a e connec ion eques s, wi h equal p obabili y, om a lis o idle
inpu /ou pu OXC channels. I he connec ion is no a ailable i is blocked and egis e ed, and hen we gene a e a di e en
eques . O he wise, we
look
a he RCM o ind all possible pa hs and he con ols
o
be ope a ed. Following a ou ing
algo i hm, we choose one pa h, upda e he NSM and hen egis e he connec ion. The blocking p obabili y is calcula ed and
ano he eques can be p ocessed. When he NSM is
111
(no mo e connec ions a e a ailable) i is ese and a new i e a ion
begns.
Tlus
p ocess is con inued un il he blocking p obabili y alue is s abilised o each ac i e channel.
Simula ions add ess
wo
di e en ou ing app oaches. The s app oach andomly chooses an a ailable pa h om he RCM.
The second app oach applies a ou ing s a egy we call Emp ies S a us Ma ix (ESM).
This
s a egy e alua es e e y NSM
a e each possible pa h is ied, and chooses ha p ecluding
less
unused connec ions, which
is
he op ion ha lea es mo e
ee elemen s
in
he ma ix.
I
he e a e mo e han one mos e ec i e op ion, he choice is made a andom.
Resul s a e d awn in Figu e
3
showing a sensible imp o emen when he
ESM
has been applied.
A
blocking
o
10%
is
eached
o
66% and 80% o ac i e channels wi h and wi hou ou ing s a egy espec wely. The
peak
alues
a e
70%
and
SOYO
eached a 90% and 94%
o
ac i e channels espec i ely. A d awback o
his
s uc u e is ha i becomes comple ely
blocked, i.e. no mo e connec ions a e possible e en when he e a e idle inpu /ou pu OXC
po s
and he NSM becomes
comple ely ull. Usable OXC wi hou o al bloc-
is
88% o ac i e channels
and
94% when ESM
has
been applied.
Besides, he
peak
o al blocking is 91% and 67% espec i ely (see Figu e 3).
NSM is an abs ac ion o he RCM and hence he node elemen agen mus upda e i . None heless, he implemen a ion
independence and he bina y na u e o he NSM ease he OXC manageabili y wha ep esen s a clea ad an age o he
Con igu a ion and P o ec ion Manage . Mo eo e , new h eshold pa ame e s can be de ined in he NSM
o
deal wi h a ic
capaci y exhaus , wha can
be
used by he Pe o mance Manage .
5.
Discussion
A new objec class has been p oposed
o
he c oss-cohec ion agmen o he In o ma ion Model wha ep esen s a
specialisa ion
o
ou ing sub-ne wo ks
in
WDM anspo ne wo ks. This class
allows
he
manage o ope a e c oss-
connec ing nodes wi h diminished connec ion capabili ies. Using
a
new no a ion me hodology
o
desc ibe an OXC ou ing
bc ionali y (WTM), he Rou ing Con ol ma ix (RCM) can be ound. WTM and RCM a e a clea way o desc ibe
comple ely he a chi ec u e and ope a ion o he c oss-connec ing sub-ne wo k.
A new ma ix called Node S a us Ma ix has
been
de ined om a Managemen poin o iew ha elaxes he p ocessing and
memo y equi emen s and minimises messaging in o ma ion. This Ma ix along wi h he RCM allows a p o-ac i e
managemen app oach om he Ne wo k Elemen Le el.
To
demons a e
all
hese ad an ages, we ha e e alua ed he
in e nal blocking p obabili y
(as
a unc ion o ac i e channels) o an OXC s uc u e used
as
an example, which is no s ic ly
non-blocking. De ini ion o he NSM has allowed
us
o apply a simple
ou ing
s a egy ha
has
lead o a sensible dec ease in
he OXC in e nal blocking p obabili y.
6.
Re e ences
[l]
S.Tomic,
e
al.,
ACTS MOON Deli e able, No.
A231.P01.120.DS.P.022.b1,
Decembe 1998.
[2] L.Be helon,
e
al,
ACTS MEPHISTO Deli e able, No.
AC0209/UPC/TSC/GCO/P/Ol7/bl,
June 1999.
[3]
ITU-T
Recommenda ion M.3100, July 1995.
[4] K.Oguchi, J. o Ligh . Tech.,
Vol.
14,
no. 6, pp. 1255-1263, June 1996.
168