SS7

ppT=áåíêçÇìÅíáçå

Users

T U

SS7 overview

P

SS7 applications

I

CAP INAP INAP BSS BSS RAN RNS MAP CAP

S

 AP  AP+  AP  AP

P MTP 3

• circuit-related and n non-circuit on-circuit applications applications (inter-exchange, not on access interfaces) • layered layered design design (transport + application) • common channel channel signallin signalling g (associated or quasi-associated) • transport transport over PCM lines, lines, ATM, IP

• call handling handling in PSTN PSTN & PLMN • mobility mobility & roaming • IN call call handling handling • RAN—core/R RAN—core/RAN AN signalling signalling

(ISUP, TUP) (MAP, BSSAP+) (INAP, CAP) (BSSAP, RANAP, RNSAP)

SP

Processor

Application (“user part”) ex. ISUP

SL

Transport MTP

SCTP

MTP 1

ATM

IP

PHY

L1 + L2

Processor

call handling

ISUP message handling

MTP 3

MTP 2

MTP 3

error control

ST

SP

transmission

ST MTP 1

LS MTP 1 – signalling signalling data data link MTP 2 – signalling signalling link link MTP 3 – signalling signalling networ network k

SL: channel for signalling messages LS: all sig. links connecting two points SR: predetermined end-to-end path

0

16

ATM ATM BS C BSS BSSAP BSSAP CAMEL CAMEL C AP AP GSM GSM HL R INAP INAP

Asyn Asynch chro rono nous us Trans Transfe ferr Mode Mode Ba ssee St St at at io io n C on on tr tr ol ol le le r Ba se se St St at at io ion Sy Syst em em Base Station Station System System Applic Application ation Part Customised Customised Applicatio Application n for Mobile network  network  Enhanced Logic C AM AM EL EL Ap Ap pl pl ic ic at at io io n P ar ar t Global Global System System for for Mobil Mobilee commu communic nicati ations ons H om om e L oc oc at at io io n R eg eg is is te te r Intell Intellige igent nt Netwo Network rk Appli Applicat catio ion n Part Part

ISDN ISDN I SU SUP IP LS M3UA M3UA M AP AP M SC SC M TP TP P CM CM PLMN PLMN

31

synch

PCM coded speech 8000 samples x 8 bits  64000 bps

SS7_SF_01_060418

M3UA

MTP 2

ISUP `

STP

SP

MTP 3b SAAL-NNI

Classic SS7 layered structure

MTP rerouting only

STP

SCCP

over PCM over AT ATM over IP

SS7 network elements

local / transit exchange MSC, BSC, HLR, ... SSF, SCF, ...

TCAP

U

Integ Integrat rated ed Serv Service icess Digit Digital al Netw Network  ork  I SD SDN Us er er Pa rt rt Internet Pr Protocol Link Set MTP3 MTP3 Use Userr Adapt Adaptat atio ion n M ob ob ilil e Ap Ap pl pl ic ic at at io io n Pa Pa rt rt M ob ob ilil e Sw Sw itit ch ch in in g Ce Ce n ntt rree M es es sa sa g gee Tr Tr an an sf sf er er Pa Pa rt rt P ul ul se se Co Co de de Mo Mo du du la la ttii on on Public Public Land Land Mobi Mobile le Net rk 

PSTN PSTN PS RA N RANAP RANAP RN S RNSA RNSAP P SAAL SAAL SCCP SCCP S CF CF SCTP SCTP

PCM line (E1) 32 timeslots x 64 kbps  2 Mbps

Public Public Switc Switched hed Telepho Telephony ny Netw Network  ork  Packet Switched Ra d dii o A cc cc es es s N et et wo wo rrk k  RAN Applicatio Application n Part Ra d dii o N et et wo wo rrk k Su Su bs bs ys ys te te m RNS RNS Applic Applicati ation on Part Part Signal Signalli ling ng ATM ATM Adapta Adaptatio tion n Layer Layer Signal Signalli ling ng Connec Connectio tion n Contr Control ol Part Part S er er vi vi ce ce Co Co nt nt rro o l F un un ct ct io io n Strea Stream m Contro Controll Trans Transmis missio sion n Protoc Protocol ol

SL SP SR SS7 S SF SF ST S TP TP TCAP T UP UP UMTS

Signalling Link   Signalling Po Point Signalling Route Si gn gn al al lilin g Sys te tem No No. 7 S er er vi vi ce ce S wi wi tc tc h hii ng ng Fu Fu nc nc ttii on on Sign al allin g Termin al al S ig ig na na llll in in g T ra ra n nss fe fe r P oi oi nt nt Transactio Transaction n Capabilit Capabilities ies Applicatio Application n Part T el el ep ep ho hon e Us er er Pa Pa rt rt Universal Universal Mobile Mobile Telecommu Telecommunicati nications ons System System

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MTP level 2 functions

Users

T U

Signalling Link states

• transmission of level 3 messages in signal units • error detection and correction • signal unit delimitation • link alignment • link error monitoring • routing label for MTP 3 • user part information



MSU

16

max 8 * 272

8

CK

SIF

SIO

for error detection

2 2 NI

2 6 LI

4

1



LSSU

8

CK

SF 5

3 SI

SIO, SIN, SIE SIOS, SIPO, SIB 16 

FISU

2 6

CK • 0  FISU • 1 or 2  LSSU • 2..63  MSU

SS7_SF_02_ 060418

LI

2 6

16

LI

EC

8

EC

F

7

   B    I FSN    F

SI

• NI  national / international network • SI  SCCP, ISUP, TUP, …

16

16

1

Level 3 order

7

bits

F

8

EC

F

bits

no retransmissions of FISU and LSSU

Aligned ⊗ MSU FISU SIB SIPO

# of errors ⊗

AERM

MTP 1

MTP 3b

M3UA

SAAL-NNI

SCTP

ATM

IP

PHY

L1 + L2

High error rate on the link

4

Normal alignment (max 5X) Failure

Emergency alignment (max 1X) # of errors

Ok

3 2

1

1

for delimitation all fields between flags require "bit stuffing": SEND: add 0 after every 11111 RECV: delete 0 from every 111110 16

⊗

TCAP SCCP

   B    I BSN    B

acknowledgements & retransmissions

8

Proving SIN or SIE

bits

 AP  AP+  AP  AP

P

MTP 2

Alignment failed

Not aligned SIO

BSS BSS RAN RNS MAP CAP INAP

U

MTP 3

Idle – Out of service SIOS

Normal or Emergency alignment

Proving OK

P

I S

Failure Ok 0.5 sec

8.2 sec

Loss of alignment 64 ⊗

-1 if 256 SUs OK +1 if faulty SU

SUERM t

AERM BI B BS N CK EC F FIB F IS U F SN

Alignment Error Rate Monitor Ba ck wa rd In di ca tor Bi t Ba ck wa rd Se qu en ce Nu mb er Check bits Error Control Flag Fo rwa rd In di ca tor Bi t Fi ll -I n Si gn al Un it F rd Se N um b

LI LSSU M SU M TP NI SF SI SIB SIE

Length Indicator Link Status Signal Unit M es sa ge S ig na l Un it M es sa ge T ra ns fe r P ar t Network Indicator Status Field Service Indicator Sta tu s In di ca ti on Bu sy Status Indication Em

S IF SIN S IO SIO SIOS SIPO SU SUERM y alig

t

S ig na ll in g In fo rm at io n Fi el d Status Indication Normal alignment S er vi ce In fo rm at ion Oc te t Status Indication Out of alignment Status Indication Out of Service Status Indication Processor Outage Signal Unit Signal Unit Error Rate Monitor

jqmI=é~êí=ff

Users

T

MTP level 3 functions • message routing • load sharing • message discrimination • message distribution • signalling network management • signalling link testing

NI,DPC  SL SLS  one of SLs NI,DPC  deliver or reroute SI  user part

0: SNM 1: SNT 3: SCCP 4: TUP 5: ISUP

MTP addressing

SIF

SIO routing label

12+4 UP msg

[ CIC ]

TUP and ISUP only

for load sharing

4

14

SLS

14

OPC

where FROM

DPC

2 2

2 bits

NI

where TO

SI national (2) international (0)

indicate node where UP creates/receives the message, not STP address

National address assigned nationally

e.g. 2 – 8277 NI

International address assigned by ITU-T

2-55

2-66

STP

STP

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U

P

P

SCCP

MTP 3

SLC=0

MTP 1

=1

SP

SP

2-10

2-20

DPC LS 2-20 2-20 2-55 2-66 2-30 2-55 … …

SLC 0 0 or 1 0 or 1 0 or 1 …

MTP 3b

M3UA

SAAL-NNI

SCTP

MTP 2 ATM

IP

PHY

L1 + L2

SP

2-30 high priority load sharing (among SLs) load sharing (among LSs)

SNM & SNT

Example procedures

• Signalling link management control locally connected links • Signalling traffic management divert signalling among available links • Signalling route management distribute status & routing info • Signalling link testing after alignment and periodically

OPC/DPC

COO COA

e.g. 0 – 7-246-1

divert signalling from unavailable link rerouting to DPC=x not possible

TFP RST

periodic test: rerouting possible?

TFA

rerouting to DPC=x possible again

SLTM

done by both sides test bit pattern sent

SLTA

Signalling Area Network Code SS7_SF_03_ 060418

U

Routing & load sharing

messages sent in MSUs point code

C IC D PC LS LSSU M SU NI

C ir cu it Id en tit y C od e D es ti na ti on Po in t C od e Link Set Link Status Signal Unit M es sa ge S ig na l U ni t N t k I di t

O PC SANC SI S IF S IO SL

O ri gi na ti ng Po in t C od e Signalling Area Network Code Service Indicator S ig na ll in g In fo rm at io n Fi el d S er vi ce In fo rm at ion Oc te t Si lli Li k  

SLC S LS SNM SNT UP

Si gn allin g Lin k Cod e S ig na ll in g Li nk Se le ct io n Signalling Network Management Signalling Network Testing User Part

ISUP functions

Users

T U P

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP

• circuit-related call control (setup, conversation, cleardown) • link-by-link signalling • interworking (older ISUP and other systems) • support for basic and supplementary services

TCAP

U P

SCCP MTP 3b

M3UA

SAAL-NNI

SCTP

ATM

IP

PHY

L1 + L2

MTP 3 MTP 2 MTP 1

E

OP

L N K K

K

P = Pointer

H

L = Length

L N H H

E

N = Parameter name

D

through-connect  charge

no CIC in SCCP

SIO

L E

select circuit create message through-connect 

select circuit through-connect  basic call setup

IAM IAM T7 ACM

ACM

L P P P D OP E D

OP = Optional Part

CIC

C

 S   L     S  

B

called party found event, e.g. alerting

CPG

CPG T9

mandatory mandatory message variable fixed type

optional

Example flow

T7: max 20 .. 30s T9: max 1.5 .. 3 min expiry  release

Message structure also SCCP SIF

fprm

ANM

ANM

connect ring tone (if speech) called party answer through-connect 

CPG

CPG

OPC DPC T2: max 3 min expiry  release A

event, e.g. on-hold, forwarding, … e.g. analogue on-hook

SUS

SUS

RES T2

RES

suspend & resume

 ABC

disconnect stop charging

EOP = End of Opt. Part

REL

REL T1 RLC T5

Interworking with other versions of ISUP

e.g. analogue off-hook

RLC

circuit released

call release O&M: block

CGB Confusion message ABC CFN • unknown msg • bad param • unknown param • re-send modified message • send another message • release call

SS7_SF_04_ 060418

Parameter compatibility info ABC • param X • param Y • param Z • param info

CGBA

T1: max 15 .. 60 sec expiry  restart, resend

block group of circuits O&M: unblock

T5: max 5 .. 15 min expiry  circuit reset

CGU

unblock group of circuits

CGUA

• param X: notify / discard / pass / release call • param Y: . . . . . / . . . . . . /. . . . . /. . . . . . •... info what to do with unrecognized parameters

C IC D PC ISDN I SUP O PC

C ir cu it Id en tit y C od e D es ti na ti on Po in t C od e Integrated Services Digital Network  I SDN Us er Pa rt O ri gi na ti ng Po in t C od e

SCCP S IF S IO S LS

Signalling Connection Control Part S ig na ll in g In fo rm at io n Fi el d S er vi ce In fo rm at io n O ct et S ig na ll in g Li nk Se le ct io n

SCCP functions

Users

T U P

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U P MTP 3

SCCP MTP 3b

M3UA

SAAL-NNI

SCTP

• • • •

addition to MTP global addressing & routing using GT non-circuit related signalling connectionless and connection-oriented

SCCP addresses

p``m

combination of

ATM

IP

PHY

L1 + L2

GT: +48… SCCP messages format same as in ISUP UDT UDT UDT UDTS

CR setup CC DT1

data transfer

DT1 dest ref no user data DT1 IT RLSD

release

SS7_SF_05_ 060418

RLC

Connectionless • address included in each message UDT • each message routed independently called addr • GT translation in each node calling addr • class 0  basic user data • class 1  sequenced delivery sent if error • used in GSM/UMTS core network CR

Connection-oriented

CC

• addresses included in CR only • logical connection  ref numbers • fixed path in the network • class 2  basic • class 3  flow controlled

DT1 DT1 IT

routing distribution

+48601…

+486014…

+48601445

GT translation start of GT  next node DPC

GT translation (optional) SSN  SCCP user

Addressing in 3GPP network Call interrogation GT = MSISDN, NP = E.164, SSN = 6 HLR

GMSC

First contact GT = MGT, NP = E.214, SSN = 6 IMSI = 260 01 1234567890 MGT = +48 603 1234567890

Other cases GT = preconfigured or received earlier

MSC/VLR

• used between MSC and BSC/RNC sent when idle (5 .. 10 min)

RLSD RLC



SCCP modes

UDT

DT1



GT = digits + numbering plan + translation type + nature of addr SSN = number (1..255) identifying SCCP user

MTP 2 MTP 1

• GT • SSN • SPC

T(ias) expires  send IT T(iar) expires  release anything received  T(iar) reset T(iar) > 2 * T(ias)

SCCP management • maintain status info on other nodes & their subsystems • MTP indications  node status • own broadcasts & tests  subsystem status

CL CO D PC E.164 E .2 12 E.214 GT M GT

Connectionless Con nection Oriented D es ti na ti on Po in t C od e ISDN/telephony numbering plan I MS I nu mb er in g pl an ISDN/IMSI numbering plan Global Title M ob il e G lo ba l T it l

MSISDN NP RNC S SN S PC SCCP TT

Mobile Subscriber ISDN Number Numbering Plan Radio Network Controller S CC P S ub sy st em N um be r S ig na ll in g P oi nt C od e Signalling Connection Control Part Translation Type

Users

TCAP functions T U P

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U P

SCCP

MTP 3

MTP 3b

M3UA

SAAL-NNI

SCTP

q`^m

• generic services for application entities • transaction-oriented communication • component handling • dialogue handling

ASN.1 and BER • higher layer protocols  complex data types • separate notation (ASN.1) from coding (BER) • complex types made from basic types  primitives & constructors

MTP 2 MTP 1

ATM

IP

PHY

L1 + L2

TCAP user operations Protocol model

Application Entities

INAP

MAP MSC

MAP VLR

TCAP

TCAP

TCAP

Network Service Part

Component sublayer components: INVOKE, RET. RESULT, RET. ERROR invoke id n

Tag



what IT is



Tag

Length



how long IT is



Length

Content



here IT is 

TCAP + MAP message Transaction sublayer messages: BEGIN, CONTINUE, END transaction id nnn

MTP+SCCP

Message type tag

ex.

BEGIN

Message length

TCAP + MAP example new subscriber in VLR: location update new VLR

Transaction Id tag Transaction Id length

old HLR

BEGIN 123 INVOKE  Update location (IMSI,MSC/VLR addr) CONTINUE 123 INVOKE  Insert subscriber data (MSISDN,services) CONTINUE 123 RET. RESULT 

VLR



ex. 123



ex. INVOKE



ex. 

Operation code



ex. Update Location

Operation parameters



ex. IMSI, MSC/VLR addr

Transaction Id Component portion tag Component portion length Component type tag

BEGIN 456 INVOKE  Cancel location (IMSI)

Component length Invoke Id tag Invoke Id length Invoke Id Operation code tag

END 456 RET. RESULT 

Operation code length

END 123 RET. RESULT Update location (HLR addr)

SS7_SF_06_ 060418

AE ASN.1 BER H LR IMSI INAP

Application En tity Abstract Syntax Notation One Ba sic En cod in g Ru les H om e L oc at io n Re gi st er International Mobile Subscriber Identity Intelligent Network Application Part

M AP MS M SC N SP TCAP VLR

M ob il e Ap pl ic at io n Pa rt Mobile Station M ob il e Sw it ch in g Ce nt re N et wor k Ser vi ce Pa rt Transaction Capabilities Application Part Visito Lo ti Regist

j^mI=é~êí=f

MAP interfaces in GSM/UMTS

Users

T

E: • inter-MSC handover or relocation • SMS transfer

B

MSC

P

VLR

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U P

SCCP

MTP 3

G: IMSI and triplets retrieval

MTP 3b

M3UA

SAAL-NNI

SCTP

MTP 2

E C: • interrogation at MT call (GMSC) • interrogation at MT SMS transfer

U

B: internal (not standardised)

G

B

MSC

D: location and subscriber data management (CS)

MAP “versions”

IP

PHY

L1 + L2

Every operation comes with Application Context version

VLR

“IN”: MS state/location requests; DUSSD requests from MS

C

MTP 1

ATM

MAP operation (sent in component)

AC version (sent in TCAP dialogue portion)

E F

SMS-GMSC

UPDATE LOCATION

gsmSCF

SMS-IWMSC

“IN” C

Gd: SMS transfer

fixed part: “ETSI mobile GSM MAP AC”

H: triplets requests (not standardised) EIR

HLR

H

AC name: “networkLocUpContext” 1 name  few operations (1..7)

AUC

Gf F, Gf: IMEI verification

SGSN

Gr: location and subscriber data management (PS)

Gc

BEGIN OPEN AC v3 INVOKE OP-X (…)

initial version based on dest addr (or default)

ABORT

alternative version offered

operation component optional

GGSN

Gc: interrogation at networkrequested packet session (optional)

Notes • MSC  MSC server if split architecture (Rel-4) • HLR+AUC+other database  Home Subscriber Server (HSS, Rel-5) • MAP also for: location services (R99), Gateway Location Register (GLR) • SCCP CL class 0 and 1 used, SSN mandatory

SS7_SF_07_060418

version (1,2,3,4)

Version negotiation Gr

Gd

4–0–0–1–0–1–3

AC A UC CL CS E IR GGSN G MS C GPRS

ABORT AC v2

BEGIN OPEN AC v2 INVOKE OP-X (…) CONT/END ACCEPT AC v2 INV/RET OP-Y/X (…) Applica tion Con text A ut he nt ic at io n Ce nt re Connectionless Circuit Switched E qu ip me nt I de nt it y Re gi st er Gateway GPRS Support Node G at ewa y M SC Ge l Pack Radio Servi

HL R IMEI IMSI IN IWMSC M AP M SC MT

new dialogue version OK dialogue portion not used later

H om e Lo ca ti on Re gi st er International Mobile Equipment Identity International Mobile Subscriber Identity Intelligent Network   Interworking MSC M ob il e Ap pl ic at io n Pa rt M ob il e Swi tc hi ng C en tr e Mo bil T i ti

NP PD P S CF SGSN S SN USSD VLR

Numbering Plan Pa ck et Da ta Pr ot oc ol S er vi ce Co nt ro l Fu nc ti on Serving GPRS Support Node S CC P S ub sy st em N um be r Unstructured Supplementary Service Data Visitor Location Register

Example MAP procedures

j^mI=é~êí=ff

Users

T

MSC

location update (new subscriber, TMSI used)

update location info in HLR & get subscriber profile

VLR

BI

MSC

VLR

Send Identification return IMSI & unused triplets

E RR Send Identification BI

Update location

CI

Insert subsc. data

Cancel location

E RR Cancel location

delete subscriber record

E RR Provide roaming no

BI

Check IMEI

SGSN

P

BI

Send routing info

E RR Send routing info

GMSC

incoming call with MSISDN

TCAP SCCP MTP 3b

M3UA

SAAL-NNI

SCTP

MTP 3

MO Forward SM

continue call with received MSRN

return serving MSC address

MSC

return white/grey/black

BI

E RR MO Forward SM

HLR

EIR

E RR Check IMEI

 AP  AP+  AP  AP

P

ATM

IP

PHY

L1 + L2

SMS-IWMSC

BI

Provide roaming no

BSS BSS RAN RNS MAP CAP INAP

U

MTP 2

SMS via GPRS from MS

E RR Update location

check phone e.g. at call setup

I = INVOKE RR= RETURN RESULT

I S

MTP 1

C RR Insert subsc. data

allocate & return MSRN

B= BEGIN C= CONTINUE E= END

HLR

BI

BI

U

SMSC

Forward MO SM

E RR Forward MO SM

SMS-GMSC

Send routing info for SM B I

BI

Forward MT SM

E RR Send routing info for SM

to/from SMSC: not MAP

VLR

MT Forward SM

BI

deliver SMS E RR MT Forward SM

suppl. service management

BI

Activate SS

CI

Get password

(components sent C RR Get password to/from MS) E RR Activate SS USSD request BI Process USS req received from MS E RR Process USS req

HLR

MSC

code required e.g. for barring services

VLR

BI

Reset

BI

Reset

sent to all VLRs and SGSNs on HLR reload loc. update redone on radio contact for all IMSIs from HLR

gsmSCF

Process USS req request handled in E RR Process USS req MSC, HLR, gsmSCF, or elsewhere

SGSN

HLR

BI

B / C / E I / RR

SS7_SF_08_060418

E RR Forward MT SM

IMSI MO MSISDN MSRN

BEGIN / CONTINUE / END INVOKE / RETURN RESULT International Mobile Subscriber Identity Mobile Originated Mobile Subscriber ISDN Number Mobile Station R ing Numb

MT SM SMSC TMSI USSD

Mobile Termin ated Short Message Short Message Service Centre Temporary Mobile Subscriber Identity Unstructured Supplementary Service Data

jqm=çîÉê=^qj

Functional overview

Users

Message handling T

as classic MTP level 3, except: • max SIF size is 4095 octets (was 272) • new SNM procedure: extended changeover

U

more than 4 octets MTP 3b

SIF

P

BSS BSS RAN RNS MAP CAP INAP  AP  AP+  AP  AP TCAP

U P

SCCP

SIO MTP 3

4 octets

"simulation" of signalling link link status control

SSCF

sequence and error control flow control connection-oriented transmission

SSCOP

error detection padding to m*48 octets

4 oct

0..3

Trailer

Pad

CPCS

0..47

Trailer

Pad

max 4096 Info

n*48 octets sent as n ATM cells no header / trailer added

SAR

Info

48 octets

48 octets

SAR PDU

SSCF PDU

SCTP

MTP 1

ATM

IP

PHY

L1 + L2

Trailer: • CRC for error detection • Length of Info • User-to-User Info not used • CP Indicator by SSCOP

max 65535

48*m octets

CP AAL 5

M3UA

Sent in Sequenced Data PDU Trailer: • PDU type (= SD here) • Pad Length (0..3) • N(S) – 24-bit send seq num

4*n octets 8 oct

MTP 3b SAAL-NNI

MTP 2

SSCF PDU

SSCS

   I    N    N      L    A    A    S

I S

SAR PDU • uses ATM User-to-User Indication bit:  last/not last segment  in Payload Type in ATM header

payload for one ATM cell

SSCF & SSCOP procedures Normal link alignment alignment order

Error control other side does the same

BGN

SD

BGAK link proving: repeat 1000 times max 30 sec alignment successful

SS7_SF_11_060418

SD

(Normal)

POLL STAT SD POLL STAT

(In Service)

ignored

polling every 100 ms

N(S)=1 N(S)=2 N(S)=3 N(S)=4

SD

POLL N(S)=5 STAT N(R)=3, lost list SD

N(S)=3 N(S)=4 N(S)=5

reply to polling

N(S)=6 N(S)=7 N(S)=8 N(S)=9

USTAT

N(R)=7, lost list

SD

N(S)=7 N(S)=8 N(S)=10 N(S)=11

error detected ATM CP CPCS C RC N NI N (R) N (S ) PDU SAAL SAR SDU S IF S IO SNM SSCF SSCOP

Asynchronous Transfer Mode Common Part CP Convergence Sub-layer C yc li c R ed un da nc y C he ck   N et wo rk N od e I nt er fa ce R ec ei ve s eq ue nc e Nu mb er S en d s eq ue nc e N um be r Pr ot oc ol Da ta Un it Signalling ATM Adaptation Layer Segmentation And Reassembly Ser vi ce Da ta Un it S ig na ll in g In fo rm at io n Fi el d S er vi ce In fo rm at io n O ct et Signalling Network Management Service Specific Coordination Function Service Specific Connection Oriented Protocol

ppT=çîÉê=fmI=é~êí=f Some SS7 over IP interfaces IP-based UTRAN

non-IP PLMN/PSTN MAP

HLR

HLR

MAP

VLR

ISUP MSC server 

RNC

GMSC server 

SG

• based on TCP • acknowledged, packet-oriented error-free, nonduplicated data transfer • data segmentation • resistance to blind attacks • multi-homing support (primary + backups)

G/MSC

if DATA

ISUP traffic MGW

U

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U

P

P

SCCP MTP 3b

M3UA

SAAL-NNI

SCTP

MTP 3 MTP 2 MTP 1

ATM

IP

PHY

L1 + L2

SCTP packet

RNSAP

RNC

T

SCTP functions

IP-based CS core network

RANAP

Users

MGW

• type, length, flags Chunk[s] Header • stream id • SSN, TSN • other fields one or more in packet (“chunk bundling”)

• verification tag • src + dest port num • checksum

TE

primary Example packet flow IP-based Servers (IPS) Application Servers (AS)

if point-to-point if via SG

Protocol overview standardised for UTRAN and core net

TCAP User SCCP User

User Part

User Part

MTP 3

MTP 3

M2UA SCTP IP L1+L2

M2PA SCTP IP L1 L2

User Part

TUA

M3UA SCTP IP L1+L2

SCTP IP L1+L2

SS7 over IP options

SS7_SF_12_060418

SCTP IP L1+L2

0 INIT

tag X [, backup addrs]

start association

X INIT ACK

tag Y, cookie [, backup addrs]

cookie = encrypted protocol state data

Y COOKIE ECHO cookie

[ DATA ]

X COOKIE ACK

[ DATA ]

Y DATA

TSN, SSN, payload data, …

Y DATA

DATA

X SACK

TSN, duplicates, gaps

SCCP

Y DATA

DATA

retransmissions to backup addr

MTP 3

Y DATA

DATA

too many retrans.  use backup

MTP 2

Y HEARTBEAT

MAP/   /CAP TCAP

SUA

backup

Signalling Points (SP)

DATA

also sent to inactive

X HEARTBEAT ACK MTP 1

primary restored

Y DATA

classic SS7 AS CS IP IPS M2PA M2UA

Application Ser ver Circuit Switched Internet Protocol IP-based Server MTP2 User Peer-to-peer Adaptation MTP2 U r Adaptatio

M3UA MG W SCTP SG SP S SN

MTP3 User Adaptation Me di a Ga te wa y Stream Control Transmission Protocol Signalling Gatewa y Signalling Point St r Se N um b

S UA TCP TE TSN T UA

S CC P Us er A da pt at io n Transmission Control Protocol Transit Exchange Transmission Sequence Number T CA P U se r A da pt at io n

ppT=çîÉê=fmI=é~êí=ff

Users

T U P

I

BSS BSS RAN RNS MAP CAP INAP

S

 AP  AP+  AP  AP TCAP

U P MTP 3

Addressing & routing

SCCP MTP 3b

M3UA

SAAL-NNI

SCTP

• point codes still used (also for IP nodes)

MTP 2 MTP 1

ATM

IP

PHY

L1 + L2

M3UA introduction • emulates MTP functions over IP+SCTP • supports multi-homing primary + backup(s) load sharing • two modes AS—SG IPS—IPS AS—SG (“border” signalling)

Routing Key DPC SI list optional OPC or list CIC range

MTP3 primitives

M3UA SCTP

Param

Routing Context 32-bit integer

n:1

SG

SCTP association IP addr(s)

Establishment of association ASP id

ASP id

REG REQ

ASPAC MTP3 primitives

SS7_SF_13_060418

M3UA SCTP

M3UA SCTP

IPS

IPS

• version • message class & type • length

DATA

SIO, SIF, RC

DATA

SIO, SIF, RC

DATA

SIO, SIF, RC

ASPUP ACK RKs, RCs

optional RK registration

RCs, mode

ASPAC ACK RCs, mode NTFY

RCs, status

NTFY

RCs, status

AS A SP CI C D PC IPS

RC, DPC

mode: • override • loadshare • broadcast

DAUD

RC, DPC

DAUD

RC, DPC

status: • inactive • active • pending

DAVA

RC, DPC

Applica tion Ser ver A pp li ca ti on S er ve r Pr oc es s Cir cu it Id en tit y C od e D es ti na ti on Po in t C od e IP b d S

M3UA O PC RC RK SCTP

if load sharing

Network management DUNA

IPS—IPS (“peer-to-peer” signalling) User Part

Header

User Part data transfer

REG RESP RKs, RCs

User Part

Param

Example message flows

ASPUP MTP3 MTP2

…

• type • length • value(s)

ASPUP ACK

M3UA SCTP

AS

1:1

• one SCTP association  one or many RCs • dynamic RK registration possible

ASPUP

User Part

M3UA message

MTP3 User Adaptation O ri gi na ti ng Po in t C od e Routing Context Routing Key St m Control Tr mission Protocol

SG SI S IF S IO SP

remote SP down

remote SP up

Signalling Gatewa y Service Indicator S ig na ll in g In fo rm at io n Fi el d S er vi ce In fo rm at ion Oc te t Si lli g P i t