Switching systems-lecture4.ppt

8/16/2019 Switching systems-lecture4.ppt

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Dar es Salaam institute of Technology(DIT)

ETU 07420

Switching Systems

Ally, J

[email protected]


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Signaling !etw"# $SS7%


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Common Channel Signaling System No.7

An inte"natinal stan&a"& '" e(change ' in'"matin n call setu),call "uting an& cnt"l in the *ST!

Stan&a"&i+e& y the ITU-T !"th Ame"ican a"iant stan&a"&i+e& y A!SI an& /ellc"e

The SS7 netw"# enales enhance& se"ices such as 1all setu), management an& tea"&wn 1alle"ID, call '"wa"&ing, -way calling, ... Tll-'"ee $300333% an& tll $500% se"ices 6i"eless "aming 6i"eless susc"ie" authenticatin

SS7 in'"matin t"aels e" a se)a"ate netw"# essage-ase& )ac#et netw"# SS7 signaling lin#s a"e &e&icate& channels, se)a"ate '"m ice

channels


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SS7 Signaling /etween E(change The SS7 signalling system is &esc"ie& in the 8.700

se"ies ' ITU-T "ecmmen&atins.

A common channel signaling system, )timi+e& '"

&igital netw"#s, it allws &i"ect t"ans'e" ' call

in'"matin t"ans'e" etween e(change )"cess"s.

1m)"ising a nume" ' laye"e& an& m&ula" )a"ts,

each with a &i''e"ent 'unctin, it is a )we"'ul gene"al-

)u")se signaling system ca)ale ' su))"ting a "ange

' a))licatins an& a&minist"atie 'unctins, inclu&ing

ISDN (integrated services digital network)

Intelligent networks (INS)

Mobile services (e.g. cellular radio)

Network administration, oeration and management


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SS7 Architecture SS7 signaling is ut-'-an&, meaning that a signaling lin# is nt in

a ice channel

9ut-'-an& signaling enales :aste" call setu) than wul& e )ssile with in-an& signaling

using multi'"e;uency tnes

Su))"t '" intelligent netw"# 'eatu"es such as &ataase systems

Ty)es ' SS7 signaling )ints Se"ice Switching *ints $SSP


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An E(am)le ' Signaling !etw"#


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SS7 Signaling Points Service Switching Points $SSP


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Signaling Point (SP) A Signaling *int $S*% is a switching ", )"cessing n&e in a

signaling netw"#, with the 'unctins ' SS7 im)lemente&.

All Signaling *ints in a SS7 Signaling !etw"# a"e i&enti'ie& y auni;ue c&e $=4 its 0" 24 its% #nwn as a Signaling *int 1&e.

A signaling )int, at which a signaling message is gene"ate&, is

calle& the 9"iginating *int.

A signaling )int, t which a signaling message is &estine&, iscalle& a Destinatin *int.

A signaling )int, at which a message is "eceie& n ne signalinglin# an& then t"ans'e""e& t anthe" lin#, withut )"cessing thecntents ' the message, is calle& a Signaling T"ans'e" *int$ST*%.


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SS7 Signaling Links


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Tyes of SS7 Signaling Links

A (access) link

1nnects en& n&es t ST*


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%volution of SS7

1mmn 1hannel Signaling System !. 7 $i.e.,

SS7 " 17%, which was s)eci'ie& in =57530, isinten&e& )"ima"ily '" &igital netw"#s, thnatinal an& inte"natinal, whe"e the hight"ansmissin "ate $?4 #s% can e e()lite&. It

may als e use& n analg lines.

SS7 signaling has nt nly een &esigne& tcnt"l the setting u) an& su)e"isin 'tele)hne calls ut ' nn -ice se"ices als.


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A#vantages of sing SS7SS7 has see"al a&antages cm)a"e& with t"a&itinal signaling

systems. Sme ius a&antages a"e the 'llwing

'AST - the time '" call set u) is "e&uce& t less than nesecn& in mst cases.

*+ CAPAC*T, - each signaling lin# can han&le the signaling

'" see"al thusan& simultaneus calls.

%C-N-*CAL - much less signaling e;ui)ment is "e;ui"e&,cm)a"e& t t"a&itinal signaling systems.

/%L*A!L% - y using alte"nate signaling "utes, the signalingnetw"# can e ma&e e"y secu"e.

'L%0*!L% - the system can cntain many m"e signals, '"e(am)le, an& can e use& '" the" )u")ses than tele)hny.


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'un#amentals of SS7 Signaling System 7 $SS7% is an a"chitectu"e '"

)e"'"ming ut-'-an& signaling in su))"t ' thecall-estalishment, illing, "uting an& in'"matin-

e(change 'unctins ' the )ulic switche&

tele)hne netw"# $*ST!% " )ulic lan& mile

netw"# $*!%.

It i&enti'ies 'unctins t e )e"'"me& y a

signaling-system netw"# an& a )"tcl t enalethei" )e"'"mance.


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An *ntro#uction to Signaling In a tele)hny cnte(t, signaling means the )assing ' in'"matin

an& inst"uctins '"m ne )int t anthe" "eleant t the setting u)

an& su)e"isin ' a tele)hne call. /y t"a&itin, Signaling has een &ii&e& int tw ty)es

Susc"ie" Signaling i.e. signaling etween a susc"ie" te"minal

$tele)hne% an& the lcal e(change

T"un# Signaling i.e. signaling etween e(changes

Local

%&change

Local

%&change

TrunkSignalling

Su"scri"er Signalling

Su"scri"er Signalling

c

c

s

c

a

s

c

c

s

c

a

s


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Su"scri"er Signaling

1alling *a"ty 1alle& *a"ty

A!ume" /!ume"

B99C 9::

DIA@ T9!E

!U7/E

I!I! T9!E I!I! SI!A@

/ A!S6E

19!FESATI9!

B99C 9!B99C 9!


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Trunk Signaling

The T"un# Signaling has 'u"the" een &ii&e& int

1hannel Assciate& Signaling $1AS% i.e. signaling inthe s)eech channel $in-an&% " in a channel clsely

assciate& with the s)eech channel $ut-'-an&%, an&

1mmn 1hannel Signaling $11S% i.e. signaling in a

channel ttally se)a"ate& '"m the s)eech channels$ut-'-an&% an& whe"e this Signaling 1hannel iscmmn '" a la"ge nume" ' s)eech channels.


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Channel Associate# Signaling (CAS)1ha"acte"istic '" 1AS is that '" each s)eech channel the"e

is ne unamiguusly &e'ine& signaling )ath, eithe" 9n-

s)eech-)ath, i.e. the signals a"e t"ans'e""e& in the s)eech

channel $in-an& signaling% " 1hannel-assciate&, i.e. the

signals a"e t"ans'e""e& in a se)a"ate signaling channel, '"

e(am)le the line signals a"e t"ans'e""e& in time slt =? in

*1 system.

All ' these signaling systems hae a nume" ' limitatins

li#e elatiely slw, imite& in'"matin ca)acity, etc.

Switch

1

Switch

2

3oice Trunk

Signaling

Link


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Common Channel Signaling (CCS)In ty)e ' 11S, signaling '" nume"us ci"cuits can e han&le& y a 'ew

'ast signaling &ata lin#s. The signaling is )e"'"me& in th &i"ectins, with

ne signaling channel in each &i"ectin.

The signaling in'"matin that will e t"ans'e""e& is g"u)e& int signal

units $&ata )ac#ets%. /esi&es the signaling in'"matin itsel', the"e is als

nee& '" s)eech ci"cuit i&enti'icatin an& a&&"ess in'"matin $lael% an&

in'"matin '" e""" cnt"l.

SS7 is a #in& ' 11S signaling system.

SP SP

STP STP

Fice T"un#

Signaling in#


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Signaling Link 4 Signaling Link Set The cmmn channel signaling system uses

Signaling in#s $Ss% t cney the signalingmessages etween tw signaling )ints.

*hysically, a Signaling in# cnsists ' a Signaling

Te"minal at each en& ' the lin# an& sme #in& 't"ansmissin me&ia $n"mally a time slt in a *1-lin#% inte"cnnecting the tw Signaling Te"minals.

A nume" ' )a"allel signaling lin#s that &i"ectlyinte"cnnect tw signaling )ints cnstitute aSignaling in# Set.


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Signaling o#esThe te"m Signaling &e "e'e"s t the assciatin etween

the )ath ta#en y a signaling message an& the s)eech )ath

$" &ata )ath% t which the message "e'e"s.

In the Associate# mo#e ' signaling, the messages "elate&

t a call 'llw the same )ath as the s)eech etween tw

a&jacent signaling )ints.In the 5uasi6associate# mo#e ' signaling, the signaling

messages a"e 'llwing anthe" )ath the" than the s)eech.

SP SPAssociate# SP SP

STP STP

5uasi6Associate#

Signaling

/elation

Signaling Link

Set


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Signaling /oute 4 Signaling /oute Set

The )"e-&ete"mine& )ath, that a message ta#es

th"ugh the signaling netw"# etween the "iginatin)int an& the &estinatin )int is calle& a Signaling

ute. It may cnsist ' a successin ' S*ST*s

an& the inte"cnnecting Ss.

All the Signaling utes that may e use& etween

an "iginatin )int an& a &estinatin )int y amessage t"ae"sing the signaling netw"# is the

Signaling ute Set '" that signaling "elatin.


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SS7 Protocol Stack

The 9SI e'e"ence &el an& the SS7 *"tcl Stac#


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essage Transfer Part (TP)

The essage T"ans'e" *a"t $T*% is &ii&e& int th"ee leels.

TP Level 1 *hysical an& elect"ical inte"'aces ' SS7 &igital signaling lin#s

E-= $2043#s%, DS-= $=G44 #s%, DS-0 $?4 #s%, F.G $?4 #s%,

DS-0A $G? #s%

TP Level 2 Ban&les message t"ansmissin e" a )hysical lin#

Inclu&es 'lw cnt"l, )ac#et se;uencing, e""" &etectin, "et"ansmissin

TP Level Ban&les message "uting etween SS*


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SS7 Transort an# igher Layers

Telehone ser Part (TP)

Analg call ci"cuit setu)tea"&wn

*S$N ser Part (*SP)

Setu), management H "elease ' t"un# ci"cuits

Signaling Connection Control Part (SCCP) T"ans)"t laye" '" T1A*-ase& se"ices such as 300333 nume"s, wi"eless

"aming, etc. *"i&es susystem nume"s $li#e )"t nume"s in T1*UD*%, which

enale a&&"essing t s)eci'ic a))licatins at &estinatin signaling

)ints

Transaction Caa"ilities Alication Part (TCAP) Use& '" S1*-SS* cmmunicatins cnce"ning "uting ' 300333500

calls, t enca)sulate ile A))licatin *a"t $A*% messages

cntaining custme" )"'ile in'"matin '" "ing mile susc"ie"s,an& '" calling ca"& calls


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Telehone ser Part (TP)

9e"iew ' Tele)hne Use" *a"t $TU*%

The Tele)hne Use" *a"t &e'ines the necessa"ytele)hne signaling 'unctins in SS7 '"inte"natinal as well as natinal tele)hne t"a''ic. It)"i&es the same 'eatu"es '" tele)hne signalingas the" ITU-T signaling systems.

The tele)hne signals a"e t"ans'e""e& in thesignaling netw"# as the '"m ' signalingmessages, which a"e the cntents in the SI: 'iel& inthe essage Signal Units $SUs%.


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*S$N ser Part (*SP)

9e"iew ' ISU*

The ISD! Use" *a"t $ISU*% &e'ines the )"tcl an&)"ce&u"es use& t set-u), manage, an& "eleaset"un# ci"cuits that ca""y ice an& &ata calls e" the

)ulic switche& tele)hne netw"# $*ST!% " ISD!netw"#. ISU* is ca)ale ' )"cessing ISD! s)eci'icin'"matin which is m"e cm)le( than tele)hnysignaling.

ISU* is use& '" th ISD! an& nn-ISD! calls.1alls that "iginate an& te"minate at the same switch& nt use ISU* signaling.


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Commonly se# *SP Signals

*nitial A##ress essage (*A)

An IA is sent in the '"wa"& &i"ectin y each switch nee&e& tcm)lete the ci"cuit etween the calling )a"ty an& calle& )a"ty untilthe ci"cuit cnnects t the &estinatin switch. An IA cntains thecalle& )a"ty nume" in the man&at"y a"iale )a"t an& may cntainthe calling )a"ty name an& nume" in the )tinal )a"t.

A##ress Comlete essage (AC)

An A1 is sent in the ac#wa"& &i"ectin t in&icate that the"emte en& ' a t"un# ci"cuit has een "ese"e&. The "iginatingswitch "es)n&s t an A1 message y cnnecting the calling

)a"tys line t the t"un# t cm)lete the ice ci"cuit '"m the calling)a"ty t the calle& )a"ty. The "iginating switch als sen&s a "ingingtne t the calling )a"tys line.


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1mmnly Use& ISU* Signals $2%

Answer essage (AN)

6hen the calle& )a"ty answe"s, the &estinatin switch te"minatesthe "inging tne an& sen&s an A! t the "iginating switch. The"iginating switch initiates illing a'te" e"i'ying that the calling)a"tys line is cnnecte& t the "ese"e& t"un#.

/elease essage (/%L)

A E is sent in eithe" &i"ectin in&icating that the ci"cuit is eing"elease& &ue t the cause in&icat" s)eci'ie&. An E is sentwhen eithe" the calling " calle& )a"ty hangs u) the call $causeK =?%. An E is als sent in the ac#wa"& &i"ectin i' the calle&)a"ty line is usy $cause K =7%.

/elease Comlete essage (/LC)

A 1 is sent in the ))site &i"ectin ' the E t ac#nwle&gethe "elease ' the "emte en& ' a t"un# ci"cuit an& en& the illingcycle as a))")"iate.


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!asic *SP Call Control


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Signaling Connection Control Part (SCCP)

6he"e is S11*L

I!A* I! A))licatin *"tcl A* ile A))licatin *a"t

1A* 1AE A))licatin *a"t T1A* T"ansactin 1a)aility

A))licatin *a"tTU* Tele)hne Use" *a"t ISU* ISD! Use" *a"t

T* essage T"ans'e" *a"t S11* Signaling 1nnectin 1nt"l

*a"t

TUP ISUPTCAP

INAP CAP MAP

MTP

SCCP


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8hat is SCCP9

In SS7 signaling system, S11* an& T* laye" th"eetgethe" a"e "es)nsile '" signaling netw"# laye"

'unctin. S11* e()an&s the T* 'unctins in the'llwing )ints

Enale t cney a"ius nn-ci"cuit-"elate& signalingmessage.

*"i&e enhance& a&&"essing an& "uting 'unctin, an&enale t achiee the &i"ect glal t"ansmissin etween&i''e"ent SS7 netw"#s y using T $lal Title%a&&"essing.

E()an& the use" )a"t ' T*. S11* su))"ts u) t 2G?

#in&s ' su systems in stea& ' =? in T*. Enale t )"i&e cnnectinless se"ice an&

cnnectin-"iente& se"ice.


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Service 'unctions of SCCP Network

Acc"&ing t the a"ius se"ice "e;ui"ements, S11*

)"i&es 'u" classes ' se"ice tw cnnectinless se"ices an& tw cnnectin-"iente&

se"ices.

The 'u" classes a"e

Class : /asic cnnectinless class.

Class 1 In-se;uence &elie"y cnnectinless class.

Class 2 /asic cnnectin-"iente& class.

Class :lw cnt"l cnnectin-"iente& class.


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Transaction Caa"ilities Alication Part

(TCAP)

The main purpose of TCAP is to provide supportfor interactive applications in a distributed

environment.

TCAP is a general protocol which makes it easy

to introduce new features in telecommunication

networks. It reduces the need for development of

new protocols whenever new features are

introduced.


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Alications of TCAP

A))licatins ' T1A*

Data E(change etween switching systems Switching systems access netw"# &ataase cente"

!etw"# &ataases estalish "emte )e"atin

&ialgue

E(am)les ' T1A* a))licatins

ile se"ice a))licatins

:"ee )hne se"ice $300-se"ice% 1"e&it 1a"& calling

9)e"atin H aintenance a))licatins


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*ntelligent Network Alication Part

(*NAP)

The 'unctins ' I!A*

I!A* &e'ines )e"atin c"ite"in amng the I!'unctinal entities SS:, S1:, S: an& SD:.

I!A* is t"ansmitte& y S11* UDT &ata, usingcnnectinless se"ices.


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Switching systems-lecture4.ppt