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Roles of Session Border Controllers in IMS Networks

Roles of Session Border Controllers in IMS Networks. CANTO - June 2006. Agenda. Session Border Controllers What is an SBC? Why are Service Providers using them today? IP Multimedia Subsystem (IMS) What is IMS? Why are Service Providers evolving to IMS? SBC’s in IMS Networks

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Roles of Session Border Controllers in IMS Networks

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  1. Roles of Session Border Controllers in IMS Networks CANTO - June 2006

  2. Agenda • Session Border Controllers • What is an SBC? • Why are Service Providers using them today? • IP Multimedia Subsystem (IMS) • What is IMS? • Why are Service Providers evolving to IMS? • SBC’s in IMS Networks • What functions do they provide in the IMS Network? • How will SBC’s evolve within the IMS architecture? • Conclusions • Summary • References

  3. Access Network Peering Network SBC Role Today - ‘Session Aware’ SIP Normalization IPv6 / VLAN Topology Hiding DoS Prevention Firewall/NAT Load Balancing Session QoS Session Border Controller Core SIP Infrastructure Simplify, Protect and Offload

  4. Firewall/NAT Traversal • SIP Services: • SIP Proxy • Application Server • Media Server Access Networks Firewalls/ NATs SIP Endpoints Session Controller Simplify & Offload • Solves Firewall/NAT traversal from within the service provider network – Do not have to replace existing firewalls/NATs • Offloads SIP Proxy – up to 20,000 re-registers a second

  5. DoS Attack Prevention SIP Services • Provides protection against Denial of Service (DoS) attacks in the form of SIP signalling • Provides policing of individual media sessions • Example – Users Signal G.711 (voice) call, but transmit video RTP session -> Maintaining QoS for other users Access Network Core Network Session Controller Protect

  6. Topology Hiding • Provides protection against Denial of Service (DoS) by hiding internal IP addressing • Removes sensitive IP addressing and domain names from SIP headers and SDP SIP Services Session Controller Peering Network 17.3.x.x 200.2.x.x 110.5.x.x Access Network Protect

  7. What is IMS? • IMS = IP Multimedia Subsystem • IMS is a network architecture that uses SIP to provide multimedia services over IP • IMS is a technology which provides fixed/mobile network convergence • Layered architecture that separates transport (media), control (signalling) and application functions • What is TISPAN? • Telecoms and Internet converged Services & Protocols for Advanced Networks) • Standardize the migration of PSTN networks to a converged network using IMS as the core architecture

  8. Catalyst for IMS Deployment

  9. Who gains from Fixed/Mobile Convergence? • Service Providers • Optimized ‘all IP’ network reduces OPEX • Opens the fixed market’s customers to mobile operators and vice versa. • New revenue streams – ability to charge for services • End Users • Common service set available regardless of the device, the location the access medium • New services available – location based • Applications become more appealing with large subscriber base (Metcalfe’s Law)

  10. Instant mesaging, VoIP, Gaming, Videotelephony, Unified Messaging, ... Based on SIP User profiles • IMS architecture • Functional separation • Open Interfaces Roaming Security IMS Architecture IMS brings Enhancements to… SIP QoS policy control • Logical separation • of applications & network elements • Rapid application • development • No vertical silo • solutions Call Control Session Detail Records IMS Basics…

  11. Access Independent – SIP over IP (Extensions for Mobile) Open Architecture - Functional Elements Integrated through Open Interfaces Security at Network Boundaries – Protect IMS Infrastructure Roaming – User gets same apps in Home or Visited Network Access Network Access Network HSS HSS IP IMS Network Characteristics Mobile Network Peering IMS Network IMS Network Scalable Architecture

  12. SBC Features Simplify and Protect PSTN Equivalence • NAT/Firewall Traversal • Protocol Normalization • Protocol Interworking • VLANs • Geographic Resilience • Policy Enforcement • Policing • Session Admission Control • Legal Intercept • Emergency Call Handling IMS/TISPAN Requirement Management Security • Call Detail Records • EMS • SNMP • DoS Protection • Rate Limiting • Topology Hiding • Encryption Within IMS Scope

  13. PDF PDF HSS HSS IMS Architecture with SBC’s • Directs Users to Home Network • NAT/FW Traversal • Emergency Call Handling Home Network (Originator) Home Network (Terminating) • HSS service lookup to select S-CSCF Visited Network (Terminating) Visited Network (Originator) S-CSCF S-CSCF I-CSCF THIG P-CSCF I-CSCF I-CSCF * P-CSCF BGCF BGCF MGCF P-CSCF IP-CAN MGCF SG IP-CAN SG IP-CAN UE MG MG UE UE PSTN Switches PSTN Switches Registration Session Set up GSTN GSTN = SBC

  14. HSS TISPAN architecture – SBC MediaDSL access, WLAN etc Home Network (Originator) • DSCP QoS Re-mapping • Topology Hiding Media path S-CSCF Registration I-CSCF Session Set up I BCF = SBC I-BGF P-CSCF BGCF C-BGF IP-CAN MGCF MG UE PSTN Switches • Session Policing • Legal Intercept • IPv4 to IPv6 • Session Admission Control GSTN

  15. Media SBC Media SBC SBC Migration to IMS • 1:N and N:1 models • SCTP (standardized signalling transport) • Signalling compression • Physically separate the product architecture • Signalling encryption IPSec/TLS • Separate signalling & media functions • Independently scale signalling and media Signalling SBC Signalling Functions Signalling Functions SIP MEGACO/H.248 H.248 H.248 MEGACO/H.248 Control Plane Media Plane MediaFunctions RTP/RTCP MediaFunctions

  16. Signalling Signalling SBC H.248 Media Media SBC Media SBC Benefits of Split Signalling & Media • Emerging standards for converged networks (IMS, TISPAN, etc) dictate that separation is required • Media functions can be deployed at the network edge, saving $$ required to backhaul the media traffic to a central location • Physical locations can scale their signalling and media independently – Allows for flexible deployment • Integrated SBC deployments can be upgraded to Distributed configurations at any time with total reuse of hardware Media Signalling H.248 H.248

  17. Standards Organizations • 3GPP - Defined IP Multimedia Subsystem (IMS) • http://www.3gpp.org/ • ETSI TISPAN - Defining migration to IMS for Wireline networks • http://www.etsi.org/ • 3GPP 2 - IMS for CDMA • http://www.3gpp2.org/ • MultiService Forum (MSF) • http://www.msforum.org/ • Open Mobile Alliance (OMA) • http://www.openmobilealliance.org/ • Internet Engineering Task Force (IETF) • http://www.ietf.org

  18. Conclusions • Service Providers are moving to IMS/TISPAN architectures • Service Providers should invest in SBC’s that are forward compatible with IMS • SBC architecture that supports signaling and media separation is required • Today, SBC’s provide a greater set of features, than IMS requirements define

  19. Terminology • 3GPP 3rd Generation Partnership Project • A-RACF Access Resource Admission Control Function • AUC Authentication Centre • BGCF Breakout Gateway Control Function • C-BGF Access/Core Border Gateway Function • GSTN Global Switched Telephony Network • HSS Home Subscriber Server • IBCF Interconnect Border Control Function • I-BGF Interconnection Border Gateway Function • I-CSCF Interrogating Call Session Control Function • IP-CAN IP Connectivity Access Network • IMS IP Multimedia Subsystem • MGCF Media Gateway Control Function • NAPT Network Address and Port Translation • P-CSCF Proxy Call Session Control Function • PDF Policy Decision Function • QoS Quality of Service • RCEF Resource Control Enforcement Function • SBC Session Border Controller • S-CSCF Serving Call Session Control Function • SPDF Service Based Policy Decision Function • THIG Topology Hiding Inter Network Gateway • UE User Element

  20. Thank you www.newport-networks.com

  21. PDF SBC Signalling Functions Diameter / XML to external policy databases • In 3GPP wireless networks the SBC Signalling requirements are: • Proxy Call Session Control Function P-CSCF function • Interrogating Call Session Control Function (I-CSCF) • Can perform Topology Hiding Interconnect Gateway (THIG) functions where required • Contains a Policy Decision Function which can be externalized if required • In TISPAN Converged networks the SBC Signalling requirements are: • An Interconnect Border Control Function when interconnecting networks • In TISPAN the PDF is defined as SPDF (Service based Policy Decision Function) IBCF P CSCF I CSCF THIG H.248 Control of Media Plane SBC Signalling Functions = 3GPP defined function = TISPAN defined function

  22. SBC Media Functions • Currently Null function in 3GPP • In TISPAN architectures performs • Access to Core Border Gateway Function (CBGF) • Interconnect Border Gateway Function (IBGF) H.248 Control of Media Plane I / C BGF SBC Media Functions = 3GPP defined function = TISPAN defined function

  23. PDF PDF HSS HSS TISPAN architecture with SBC’s Home Network (Terminator) Home Network (Originator) Visited Network (Terminating) Visited Network (Originator) S-CSCF THIG S-CSCF THIG I-CSCF* P-CSCF I-CSCF* I BCF I BCF I BCF P-CSCF BGCF I BCF I BCF BGCF MGCF P-CSCF IP-CAN MGCF SIP-I IP-CAN MG IP-CAN UE MG UE UE PSTN Switches PSTN Switches Registration Session Set up GSTN GSTN = SBC

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