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8/20/2019 TekelecDSR Presentation GSIF
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Diameter Signalling Router
David PrinceDirector Technical Pre-Sales, APAC
Tekelec. For What’s Next.
2010 12 2
8/20/2019 TekelecDSR Presentation GSIF
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Outline
› Diameter Background› Use of Diameter in LTE/IMS/3G› Diameter Agents› The Tekelec Diameter Signaling Router – Use Cases for
International Interconnect Carriers
› Summary
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Signaling Protocol Evolution
› Diameter and SIP become the dominant signaling protocols› SCTP “point-to-point” connections remain
Mobility and Subscriber Management
Application and Session Control
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Mapping of SS7 to IP protocols
› CAP* - 2G/3G CAMEL prepaid functions in future via Diameter, VAS functions of CAMELvia SIP (= INAP)
› MAP* - AAA and mobility in future via Diameter, Messaging (SMS) via SIP
SIPISUP
INAP
Call &
ServiceControl
DiameterMAP*
CAP*
Mobility &ChargingControl
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Comparing the SS7 and Diameter Protocol Stacks
› Diameter is the successor of Radius, originally used for AAA› Diameter acts as an “envelope” for applications (= interfaces)
MTPSCCP
TCAP
MAPCAP
INAP
IPSCTP
Diameter
S6, S9, S13,Gx,Gy,Gz
Cx,Dx,Sh,Dh
Rx,Rf,Ro,
DiameterProxyAgent
DiameterRelayAgent
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Diameter Fundamentals
› Defined by RFC 3588› IP-based AAA protocol designed for easy extensibility via the
definition of new Applications [interfaces], Commands[messages], and Attribute-Value Pairs (AVPs) [parameters]
› 3GPP has defined many new Diameter applications for use inIMS, LTE, and 3G
› Routing, signaling network management and congestioncontrol not as robust as SS7› Requires security via TLS or IPsec, but these are not always
used in practice
› Defines clients, servers, and 4 types of core agents
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Selected Diameter Interfaces in LTE and IMS
Foreign LTE Domain
Home LTE/IMS Domain
Foreign GPRS Domain
S13
S6a S9
S6a
GxGz
Gy
Cx
Sh
Rx
Ro
Rf
Rc Re
EIREIR
vMME vPCRF
PGW
AF
ABMF RF
OFCF
S6d
MAP-DiamIWF vSGSN
vS4-SGSN
OCF
EPC EquipmentCheck
AS Accessto HSS
IMS PCC
IMSCharging
EPCCharging
IMSRegistration
EPC MobilityManagement
MME
I/S-CSCFPCRF P-CSCF
IP-SM-GWAAAHSSHSSSLFSLF
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Types of Diameter Agents
› Relay Agent – Routes messagesbased on Realm (domain), Host,and Application. Maintainstransaction state only.
› Proxy Agent – Similar to Relay,but might also look inside themessage for routing decision,or modify the message. Mightmaintain session state.
› Redirect Agent – Returns routinginformation and then drops out ofthe loop.
› Translation Agent – Proxy agentthat translates between twoprotocols, such as Diameter-MAP.
MAPMessage Request
Answer
NE ServerTranslationAgent
MAPResponse
Request
Answer
Request
Answer
Client ServerRelay/ProxyAgent
Request
Request Redirect
Answer
ServerClient
RedirectAgent
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Diameter Comparison to SS7
Characteristic SS7 Diameter
Routing › Each message independently routed› Answer message does not contain
routing info and follows same pathas associated request
Signaling network management(SNM) and Congestion control
› Network-wide› Dedicated SNM messages› Route around failed paths› Congestion levels and traffic
priorities defined
› Hop-by-hop› No dedicated SNM messages› Failures ‘discovered’ with each new
request
› Relies on reliable transport› No defined traffic priorities
Subscriber number based routing › GTT can be used by upper layers
› Specialized, app-specific proxiesrequired
DRA for PCRF
HSS address resolution for EPC andIMS
Robustness › Wide-scale deployment; years ofexperience› Early days; lots of prove-in still
required
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Challenges Raised by Diameter
› Complexity and scalability of managing large number ofSCTP/Diameter connections
› Deficiencies with respect to network management and congestioncontrol in Diameter› Lack of wide-scale deployment and proven robustness of Diameter
› Need for address resolution function to support mapping subscribersto HSSs, particularly for LTE mobility management
› Need to provide PCRF load-sharing and binding for policy› Need for single point of interconnect to other LTE networks to simplify
routing and provide security
› Need to provide for roaming to non-LTE (2G/3G) networks› Need for visibility of critical Diameter interfaces
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Selected DSR Use Cases for Interconnect Carriers
› LTE RoamingLTE-to-LTE
LTE-to-2G/3G Roaming• MAP-Diameter Interworking
Topology Hiding
Roaming Steering
› Diameter Mediation› Centralized Monitoring
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GSMA – LTE Roaming Guidelines
› Defined in GSMA PRD IR.88Defines need for a Diameter agent at the point of networkdemarcation
S4SGSN
vPCRF
VPMN HPMN
ProxyAgent
hPCRF
ProxyAgent
S6a
S6d
S9
GRX/IPXMME HSS
ProxyAgent
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MME MME MME
Simplified S6a Network
Operator_N
HSS BEHSS BE HSS BEHSS BE HSS BEHSS BE HSS BEHSS BE
HSSFE
HSSFE
HSSFE
HSSFE
HSSFE
HSSFE
HSSFE
HSSFE
Operator_2
Operator_3
Operator_N+1
Roaming HubProvider
DSR
MMEMME
MME
DSR
MMEMME
MME
DSR
MMEMME
MME
DSR
MMEMME
MME
DSR
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
HSSHSS
DSR
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DSR Routing
› DSR allows the operator to define routing rules based on combinationsof the following data elements:
Destination-based: Realm, Host, and Application-IDOrigination-based: Realm, Host, and Application-IDCommand-CodeIMSI Address
› DSR allows the operator to prioritize rules for cases where a DiameterRequest may match multiple user defined rules
› SupportsSecurity:
• IP Sec,
• Single point of interconnect,
• Screening functions
Topology hiding,SCTP multi-homing
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S6d
S6d (R8SGSN only)
SGi
Gb Iu
GpGr
Gr
PDN
HLR PGW
SGSNR7/R8
EPS HPMN
2G/3G VPMN
HSS
IWF
Alternatives
UTRANGERAN
MAP-Diameter Interworking Function (IWF)
Target Use Case – Roaming to non-LTE network;Visited SGSN uses Gr interface (MAP)
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Diameter Mediation
› Designed to be a highly extensible protocol, new Diameterapplications and enhancements to existing applications will becommonplace
› Inevitably, vendor-specific implementations and ongoingenhancements will present interoperability issues as theseenhancements and new applications are introduced in existingDiameter networks
› DSR will support a Diameter mediation framework to assistwith timely resolution of interoperability issues
Vendor A
›DSRVendor B
Request A RequestA(B)
AnswerBAnswerB(A)
DiameterMediation
Framework
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Diameter Intelligence Hub
HSSHSS
S4 SGSNS4 SGSN MMEMME
IMS
EIR
AAA
ePDGSWm
S6d/a Swx
S13
S6d
Gy
Gz
SWx/a/m
Gy, Gz,Gx
Gx, Rx,S9
S6aS13
Rx,Cx,Dx,Sh,
S9
HSS
S4 SGSN
PDN Gw
PCRF
OCS
OFCS
IP networks
MME
HLR
vSGSN vPCRF
vMMEMAP
› Tekelec’s Diameter Intelligence Hub (DIH) isfully integrated with the DSR, eliminating theneed for additional probes and taps
› The DIH leverages virtualization technologyto deliver accounting and troubleshootingcapabilities in a common blade deploymentwith each DSR NE
› Leveraging DSR’s role as an IPSec securityassociated endpoint, visibility is maintainedover IPSec encrypted interfaces
Data Feed:• Accounting (message count like suDR)• xDR, KPI, Alarms to 3 rd party incumbent OSS/BSS systems
Troubleshooting:• Mobility Management incl. 4G/3G hand-over performance• Authentication Management
Analytics:(sample of KPIs generated from S6a, S6d):
• Update-Location-Request/Answer• Cancel-Location-Request/Answer• Purge-UE-Request/Answer• Insert Subscriber Data Request/Answer• Delete-Subscriber-Data-Request/Answer• Reset-Request/Answer• Notify-Request/Answer- For change of PDN-GW• Authentication-Information-Request/Answer
17 I Tekelec. For What’s Next. Tekelec Confidential
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Conclusions
› Diameter (and SIP become) the dominant signaling protocols› Diameter interconnect required to support
LTE Roaming
PCC (3GPP R9) connectivity between hPCRF and vPCRF› Need a robust signalling framework for DIAMETER
Provided by the Diameter Signaling Router Solution
› Main DSR Use Cases for International Interconnect CarriersGateway to other networks to support roaming and topologyhiding
• Possibly include MAP Interworking Function for interconnection with2G/3G networks
Mediation of Diameter variants in a multi-vendor environmentProbeless monitoring and network intelligence data collectionpoint for the Diameter network
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DSR collateral available
› Application Handbook› Product Brief› Download at www.tekelec.com
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Acronyms
ABMF Account Balance Mgmt. Function
AF Application Function
CSCF Call Session Control Function
DNS Domain Name System
DRA Diameter Routing Agent
EIR Equipment Identity Register
EPC Evolved Packet Core
GGSN Gateway GPRS Support Node
GRX GPRS Roaming eXchangeHSS Home Subscriber Server
IMC Inter-MP Communication
IMS IP Multimedia Subsystem
IPX IP Packet eXchangeIWF InterWorking Function
LTE Long Term Evolution
MME Mobility Management Entity
OCF Online Charging Function
OFCF Offline Charging Function
PCRF Policy and Charging Rules Function
PDN Packet Data Network
PGW PDN GateWay
RF Rating Function
SB Service Broker
SBCF Session Based Charging Function
SCTP Stream Control Transmission ProtocolSGSN Serving GPRS Support Node
SGW Serving GateWay
SLF Subscription Locator Function
SSR SIP Signaling RouterTCP Transmission Control Protocol
TLS Transport Layer Security
UE User Equipment
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References
› IETF 3588bis – Diameter Base Protocol› 3GPP TS 29.272 (v8.3.0) – Mobility Management Entity (MME) and Serving GPRS Support Node
(SGSN) related interfaces based on Diameter protocol (Release 8)
› GSMA PRD IR.88 – “LTE Roaming Guidelines”, v1.0
› 3GPP TS 23.003 (v8.6.0) – UMTS; Numbering, addressing and identification (Release 8)› 3GPP TR 29.909 (v8.1.2) – Diameter-based protocols usage and recommendations in 3GPP(Release 8)
› 3GPP TS 33.210 (v8.3.0) – 3G Security; Network Domain Security; IP network layer security(Release 8)
› 3GPP TS 23.204 (v9.0.0) – Support of Short Message Service (SMS) over generic 3GPP InternetProtocol (IP) access (Release 9)› 3GPP TR 29.805 (v8.0.0) – InterWorking Function (IWF) between MAP based and Diameter based
interfaces, (Release 8)
› 3GPP TS 29.305 (v9.0.0) – InterWorking Function (IWF) between MAP based and Diameter basedinterfaces, (Release 9)
› 3GPP TS 23.292 (v9.4.0) – IP Multimedia Subsystem (IMS) centralized services; Stage 2,(Release 9)
› 3GPP TS 23.203 (v9.3.0) – Policy and charging control architecture, (Release 9)
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Selected Diameter Interfaces in LTE and IMS
Interface Endpoints
S6a MME HSS
S6d HSS vSGSN (Rel 8)
S13 MME EIR
S9 hPCRF vPCRF
Rx PCRF AF, P-CSCF
Gx PGW PCRF
Gy PGW OCF
Gz PGW OFCF
Cx I/S-CSCF HSS
Sh AF, IP-SM-GW HSS
Rf P/I/S-CSCF, AF OFCF
Ro S-CSCF, AF OCF
Rc OCF ABMF
Re OCF RF
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Contact Details
David Prince
Director Technical Pre-Sales, APACMobile: +61.448.186.288
E-Mail: David.Prince@tekelec.com
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S6a
S9
GRX/IPX
MME
S4SGSN
HSS
vPCRF hPCRF
S6d
VPMN HPMN
ProxyAgent
ProxyAgent
Diameter Agents in 3GPP and GSMA
MMEMMEMME ...
InnerDiameter
Relay Pool
BorderDiameter
Relay Pool
HSS
Inter-Operator DiameterInfrastructure
3GPP TR 29.909 – Diameter-basedprotocols usages andrecommendations in 3GPP
• Defines need for Diameterinfrastructure to simplify the S6 and
S9 networks3GPP TS 23.203 – Policy andcharging control architecture
• Defines Diameter Routing Agent todirect all messages for the same IP-CAN session to the same PCRF
GSMA PRD IR.88 – LTE RoamingGuidelines
• Defines need for a Diameter agentat the point of network demarcation
PLMN
Diameter (PCRF) realm
S-GW
P-GW
AF
PCRF PCRF
PCRF
DRADiameter (PCRF) realm
PCRF PCRF
PCRF
DRAGx, Gxa, Gxb, Gxc, Rx
Non-3GPPGW
ePDG
24 I Tekelec. For What’s Next. Tekelec Confidential
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