sinalização ss7

8/19/2019 Sinalização SS7

1/31

SS #7

ENGR 475 – TelecommunicationsHarding UniversityOctober 17 !""#

$onat%an &%ite


2/31

Outline

' Overvie( o) **7' &%at it re+laces

' ,n -and versus out o) band signaling' -ene)its' .ac/et s(itc%ing versus circuit s(itc%ing'

Ne( )eatures' Ty+es o) circuits used in **7' .rotocol *tac/


3/31

Overview of SS7

' *ignaling *ystem 07 – 2 set o) +rotocols (%ic% are used to setu+

monitor and tear do(n tele+%one calls very3uic/ly

– Runs over a se+arate net(or/ t%an t%e actualvoice tra))ic

' .ac/et s(itc%ed

' Out o) -and – 2lso adds ot%er )eatures

' atabase access caller id load balancing )aultdetection and correction tari))s 611 trac/ing calling card)eatures


4/31

Overview of SS7

' Re+laces **# and **5 in t%e United *tates – **# (as introduced in t%e mid 16#"s

– ,t (as t%e )irst (idely used %ig% s+eed !4"" b+s8digital +ac/et s(itc%ed net(or/

– 9any +eo+le consider t%is to be t%e )irst +ac/ets(itc%ed net(or/

' :alled ::*7 in t%e rest o) t%e (orld – :ommon :%annel ,ntero))ice *ignaling *ystem

Number *even


5/31

SS7 Overview

' Not every tele+%one net(or/ uses **7 – *ome tele+%one net(or/s %ave not been u+dated

since t%e mid 16#"s – %tt+ ;;((( dmine com;+%(orld;sounds;(a(ina;

' **7 re3uires ne( %ard(are along t%e net(or/and t%is isn


6/31

SS7 Definition

' *et o) tele+%ony +rotocols and devices t%at areused to manage +%one calls 3uic/ly

– Tells t%e net(or/ (%en to start and sto+ a call (%o tobill (%o dialed etc= – Travels on a se+arate net(or/ t%an t%e actual voice

tra))ic – T%e net(or/ is a digital +ac/et s(itc%ed net(or/ as

o++osed to t%e circuit s(itc%ed voice – T%e +ac/ets %ave a de)inite )ormat but t%ey can be

variable lengt%


7/31

Pre SS7

' .%rea/ing – %tt+ ;;((( (ebcrunc%ers com;crunc%;>2? %tml – %tt+ ;;((( tele+%onetribute com;signal@and@circuit@condition

s %tm – %tt+ ;;((( ds+tutor )reeu/ com;dtm);ToneGenerator %tml

' :ontrol signals (ere +assed in band – T%e tones (ere used at t%e beginning and end o) a

conversation T%ese included' T%e numbers dialed ringing busy tone no suc% number etc=

– T%ese tones could be %eard and t%ey +assed (it% t%e actualvoice conversation to eac% device on t%e net(or/


8/31

Pre SS7

' .%rea/ing (asn


9/31

Pre SS7

' &it%out **7 call setu+;teardo(n (ould ta/earound 1! – !4 seconds

'&it% **7 call setu+;teardo(n ta/es 1 – 4seconds – **7 is used )or bot% t%e landline and (ireless

net(or/' &%at is t%e savings to t%e +%one com+any in a

year ignoring t%e costs o) t%e **7 net(or/A – 2ssume t%at t%ere are 1 billion +eo+le in t%e (orld

t%at use +%ones ma/ing 5" +%one calls a mont%T%e use o) a +%one line costs t%e tele+%onecom+any around B o) a cent +er minute


10/31

Pre SS7

' ,n band signaling +asses all control tones (it% t%eactual voice tra))ic – E3ui+ment must continually c%ec/ )or t%e control tones

because it doesn


11/31

SS7 Architecture

' 2 call must ma/e many C%o+sD travelingacross t%e net(or/ – Eac% s(itc% must /no( (%ere t%e call is

coming )rom and (%ere it is going to in orderto maintain service

– T%is ta/es a lot o) coordination' T%is is (%at t%e **7 arc%itecture

addresses


12/31

SS7 Architecture

' im+ortant devices – 1 *ignal *(itc%ing +oint **7 ca+able tele+%one s(itc%es

T%ey originate terminate or s(itc% calls' **.

– ! *ignal Trans)er +oint **7 data +ac/et s(itc%es T%eyreceive and route incoming signaling messages to t%e +ro+erlocation

' *T. – *ignal :ontrol +oint atabases distributed along t%e

net(or/ T%ey allo( advanced call +rocessing ca+abilities' *:.' T%e intelligence in t%e net(or/ is no( distributed

among ty+es o) e3ui+ment


13/31


14/31

SS7 Signaling Links

' &e are tal/ing about t%e +ac/et s(itc%ednet(or/ NOT t%e voice net(or/

– T%e voice net(or/ is still t%e digital T1 ty+einter)ace

' T%e lin/s among t%e +ac/et s(itc%es *T.8 areactually )airly slo( by our standards – 5# b+s )ull du+leF – Ho(ever t%is system %as been in +lace since t%e

mid 166"


15/31

SS7 Signaling Links

' ty+es – 2ssociated – Nonassociated – ?uasi associated

' 2ll %ave to deal (it% %o( many +ac/ets(itc%es and voice s(itc%es t%at areused


16/31


17/31

SS7 Signaling Links

' Nonassociated – T%e voice +at% is com+letely se+arate )rom

t%e signaling +at% – 9any nodes *T.s8 must be +assed t%roug%

be)ore t%e call routing signal is +assed to t%ecorrect +lace

– Iery o)ten used


18/31

SS7 Signaling Links

' ?uasi associated – Reduces t%e number o) *T.s t%at t%e

signaling in)ormation must be trans+ortedt%roug%

– Re3uires muc% more cabling but it can bemuc% )aster

– T%e signal is only allo(ed to +ass t%roug% 1*T. bet(een t%e voice s(itc%es


19/31

SS7 Signal Links

' Eac% ty+e o) lin/ is given a di))erent namein t%e arc%itecture de+ending on (%at it

does – T%e names are labeled 2 t%roug% > – >or eFam+le a : lin/ is t%e lin/ t%at occurs

bet(een a mated +air o) *T.s' T%ese designations Just %el+ us to

manage (%at ty+e o) lin/s (e are loo/ingat on t%e net(or/


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21/31

SS7 Signal Links

' T%e *:. databases8 o)ten %ave manylin/s going to t%em &%yA

' T%e **. voice s(itc%es8 o)ten %avemuc% less connections &%yA


22/31

SS7 Addresses

' *imilar to an ,. address' Every obJect %as a uni3ue address' Uses K bit numbers

– EF+ !"" 1! 14K – >irst byte is t%e net(or/ identi)ier – *econd byte is t%e cluster number – T%ird byte is t%e member number


23/31

SS7 Protocol Stack

' 9uc% li/e t%e O*, 9odel' Uses only 4 layers

– .%ysical UT. *" c%annel – ata Lin/ Error c%ec/ing;>lo( :ontrol – Net(or/ 2ddressing routing congestion

control' T%ese layers ma/e u+ t%e messagetrans)er +art


24/31

SS7 Protocol Stack

' *ignal :onnection :ontrol .art – T%e to+ layer o) t%e **7 +rotocol stac/

– T%is layer +rovides t%e actual )unctionalityt%at t%e messages contain T%ere areseveral +arts


25/31

SCCP Parts

' GTT – Global Title Translation – 2llo( s+eci)ic calls to be routed to certain

databases – Enables credit card +rocessing over t%e

+%oneline

– T%is is ty+ically (%at businesses use (%ent%ey scan your card at a restaurant


26/31

SCCP Parts

' ,*U. – ,* N User .art – 2llo(s )or t%e establis%ment and tear do(n

o) calls – &or/s )or bot% ,* N and non ,* N

net(or/s


27/31

SCCP Parts

' T:2. Transaction :a+abilities 2++lication .art – 2llo(s calling card; 1 K"" )unctionality to

access databases


28/31

SCCP Parts

' OMAP - Operations, Maintenance, andAdministration Part – 2llo(s )or maintenance o) routing tables – 2llo(s )or dynamic )lo( controlled routing

across intelligent lin/s


29/31

SS7 Packet

' :an be variable lengt% – :ontains

' *ender;Receiver +%one numbers' &%at lin/s are used' &%at devices are used' Ot%er routing in)ormation' 2 +ointer to t%e actual voice data


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SS7 Applications

' 611 en%ancements' :alling card )raud +revention' :redit card a++roval' Iirtual net(or/s' :all tracing' :all bloc/ing

' 9uc% 3uic/er call setu+;teardo(n

sinalização ss7

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