Future Signaling Protocols What’s New in IETF

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Course on future signaling protocols in 3G networks

SIP and All-IP in Fixed and Mobile Networks, Merito Forum, 28-29 April 2003.

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Future Signaling Protocols What’s New in IETF

  1. 1. Future Signaling Protocols What’s New in IETF John Loughney Research Manager Nokia Research Center john.loughney@nokia.com1 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  2. 2. Contents • Part 1 • Migration from SS7 to IP signaling. • SIGTRAN, SIP & ISUP interworking • SCTP, uses on the Internet and within 3G networks. • Part 2 • AAA and Diameter • SeaMoby • Towards hybrid 3G networks with WLAN and IP networks2 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  3. 3. SIGTRAN Documents • Standards • Architectural Framework for Signaling Transport - RFC 2719 • ISDN Q.921-User Adaptation Layer - RFC 3057 • SCTP Applicability Statement – RFC 3257 • Signaling System 7 (SS7) MTP2 - User Adaption Layer – RFC 3331 • SS7 MTP3-User Adaptation Layer (M3UA) – RFC 3332 • In IESG Review • SS7 SCCP-User Adaptation Layer (SUA) • Stream Control Transmission Protocol Management Information Base • SS7 MTP2-User Peer-to-Peer Adaptation Layer • IUA Outstanding Issues • Under Discussion • Telephony Signalling Transport over SCTP applicability statement • SS7 MTP3-User Adaptation Layer Management Information Base • V5.2-User Adaption Layer (V5UA) • DPNSS/DASS 2 extensions to the IUA protocol • M3UA Implementers Guide3 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  4. 4. SIGTRAN in 3GPP • Release 99 Packet Architecture • RANAP (Iu interface) – M3UA / SCTP • RNSAP (Iur interface) - M3UA / SCTP • Rel 4 & 5 - All IP architecture • MAP over SIGTRAN‘ (M3UA / SCTP) • CAP over SIGTRAN‘ (M3UA / SCTP) • BICC over SIGTRAN‘ (M3UA / SCTP)4 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  5. 5. SIGTRAN Network5 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  6. 6. SIGTRAN in Industry • Major protocol vendors supporting SIGTRAN protocols • HSS • Trillium/Intel • Ulticom • Conformance tests • NetTest • Etherreal • Several Public Conformance Test Events • M3UA bake-off, held in Madrid, Spain May 7-11, 2000. • M2PA interop, held in November 2001 . • SUA v08 interop held in Belgium in November 2001. • M3UA interop held by ETSI, February 2002. • SigTran interop held by ETS, October 2002.6 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  7. 7. Backhaul Traditional Telephony telephony signaling signaling over IP SEP SG SEP SP SP UA UA SS7 stack SCTP SCTP SS7 stack IP IP SEP: Signaling Endpoint SG: Signaling Gateway ISEP: IP Signaling Endpoint SP: Signaling Protocol UA: User Adaptation Layer SCTP: Stream Control Transport Protocol7 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  8. 8. Communication Within IP Networks Telephony signaling over IP SEP SEP SP SP UA UA SCTP SCTP IP IP IPSP: IP Signaling Point.8 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  9. 9. SIP & ISUP Interworking SIP (ISUP) to CPS SS7 (ISUP) MGCF SS7 (SCCP, TCAP) over IP (Sigtran) IP Transit Signalling SS7 (SCCP, TCAP) PSTN Gateway T-SGW User plane (RTP) Media Gateway E1/T1 MGW9 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  10. 10. Network View10 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  11. 11. SCTP Features and Properties • Connection-oriented, robust, reliable transport - similar to TCP. • Support of multi-homing for enhanced reliability. • Endpoints are identified by sets of IP addresses / ports • Not by IP address / port pairs, like TCP. • Enhanced initiation routines to prevent spoofing & DoS attacks. • Logically independent streams, managed under a single set of congestion controls) which prevent head-of-line blocking (each stream is similar to a single TCP connection). • The benefit of this over multiple TCP connections is that the user does not have to manage separate connections. • Current best thinking applied to congestion management.11 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  12. 12. SCTP Standards• Standards • Stream Control Transmission Protocol - RFC 2960 • SCTP Applicability Statement – RFC 3257 • An Introduction to SCTP – RFC 3286 • SCTP Checksum Change - RFC 3309 • Transport Layer Security over SCTP – RFC 3436• Waiting Publication • On the Use of SCTP with IPsec• Under Discussion • SCTP Implementors Guide • Sockets API Extensions for SCTP • Requirements for RoHC IP/SCTP Robust Header Compression • PR-SCTP (Partial Reliability SCTP) • SCTP Dynamic Address Reconfiguration • SCTP MIB12 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  13. 13. Why?• IP is everywhere but it an old protocol (RFC 793 September 1981)• TCP has acknowledged deficiencies. • Head-of-line blocking • Vulnerable to attacks • Poor support for multihoming.• New demanding networks, applications & services are IP based. • IP Telephony • Streaming Audio & Video • 3G • Advancing Hardware Design • Bandwidth, bandwidth, bandwidth ... (reliability, reliability, reliability) 13 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  14. 14. SCTP Goals • SCTP is designed to transport both PSTN signaling messages and provide general transport solution. • SCTP is an kernel-level datagram transfer protocol operating over IP offering: • acknowledged error-free non-duplicated transfer of user data • data segmentation to conform to discovered path MTU size, • sequenced delivery of user datagrams within multiple streams, with an option for order-of-arrival delivery of individual messages • optional multiplexing of user messages into SCTP datagrams, subject to MTU size restrictions • network-level fault tolerance through supporting of multi-homing at either or both ends of an association. • Appropriate congestion avoidance behavior. • Resistance to flooding and masquerade attacks.14 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  15. 15. Differences between TCP & SCTP • SCTP is connection-oriented in nature, but the SCTP association is a broader concept than the TCP connection. • The term "stream" is used in SCTP to refer to a sequence of user messages. This is in contrast to its usage in TCP, where it refers to a sequence of bytes.15 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  16. 16. Current Deployment Level • First major deployment will be with the initial deployment of UMTS networks. • Protocols Transported over SCTP • SS7 over IP (SIGTRAN) • Diameter (AAA) • SIP • BICC • Future Support • ISCSI – called IP Storage by the IETF • Remote Direct Memory Access - called RDDP by the IETF • Reliable Server Pooling protocols • CORBA16 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  17. 17. SIP over SCTP • Use of SIP over UDP is deprecated. • Advantages of SCTP over UDP • Fast Retransmit • Congestion Control • Transport layer fragmentation • Advantages of SCTP over TCP • Prevention of Head of the Line Blocking • Easier parsing due to SCTP’s message based nature. • Multihoming support adds protection against network failure. • Summary • Under a zero loss condition, SCTP transport of SIP should perform on par with TCP transport. • Under loss conditions, SCTP should perform better than TCP.17 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  18. 18. Part 2 • Diameter / AAA (Authentication, Authorization & Accounting) • SeaMoby (Seamless Mobility) • NSIS (Next Steps in Signaling)18 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  19. 19. AAA & Diameter • Next generation Authentication, Authorization & Accounting protocol • Consists of base specification and applications • MIP • Network Access Server (Dial-up / PPP / SLIP environment) • SIP Services • Accounting Extensions19 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  20. 20. Standard RADIUS Model20 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  21. 21. Diameter Roaming21 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  22. 22. How It Works • The user requests service from the remote ISP, which in tern requests the user’s credentials. • The user submits ID, password and address of his home- agent. The remote server performs mutual authentication with the home-agent and forwards the user’s credentials. • The home-agent accepts the user’s credentials and then tells the remove ISP to grant access to the user. • Subsequently, the two ISPs update their call accounting records.22 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  23. 23. AAA Elements • Diameter Node • A host that implements the Diameter protocol, and acts either as a Client, Agent or Server. • Broker • A business term used in AAA infrastructures. A broker is either a relay, proxy or redirect agent, and operated by roaming consortiums. • Diameter Agent • A host that provides either relay, proxy, redirect or translation services. • Diameter Client • A device at the edge of the network that performs access control. An example of a Diameter client is a Network Access Server (NAS) or a Foreign Agent (FA). • Diameter Peer • Node to which a given Diameter Node has a direct transport connection. • Diameter Server • A server that handles authentication, authorization and accounting requests for a particular realm.23 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  24. 24. Diameter Connections and Sessions Server relay Server Peer connection A Peer connection B User session X Translation of RADIUS to Diameter RADIUS Req Diameter Req Translation Home NAS RADIUS Ans Agent Diameter Req Server24 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  25. 25. Diameter Proxy Example local service home service provider provider Primary Primary Proxy Home Server Server Network Access Server Backup Backup Proxy Home Server Server25 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  26. 26. Diameter Extensibility • Diameter tries to preserve Radius-like flexibility • Diameter base commands and AVPs defined in the base spec • Diameter extension can define new commands and AVPs. • Examples are: • NASREQ • MOBILE-IP • 3GPP Credit Control • 3GPP Multimedia Application • New AVPs can be added26 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  27. 27. AAA-SIP in 3GPP Rel. 5 Diameter SLF HSS AS Sh Diameter ISC Dx Cx Cx Diameter Gm Mr Mw Mw UE P- I- S- MRFC CSCF CSCF CSCF Megaco Compression Mi COPS for Go SIP MRFP Policy Control GGSN Mj BGCF MGCF SGW SIP SIP-ISUP Megaco Mc Visited Home Domain Domain MGW27 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  28. 28. Work to Do • Diameter Base Specification ready for publication. • Diameter NASREQ Application nearly ready for publication. • Diameter Mobile IPv4 Application nearly ready (needed by 3GPP2). • SIP-AAA Requirements nearly ready. • CMS Security Application, needed for e2e security • Diameter Multimedia Application (3GPP rel. 6) • Diameter Credit Control Application (3GPP rel. 6) • AAA Key Distribution. • Diameter Mobile IPv6 Application open.28 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  29. 29. Summary • Integrating different access technologies (3G, WLAN, DSL, Dial-up): • increases the potential for increasing subscribers. • increases accesses to services. • Integrating/harmonizing signaling: • harmonizes network infrastructure. • simplifies network management. • simplifies charging/billing. • simplifies the user experience.29 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  30. 30. SeaMoby Status• Standards • Dormant Mode Host Alerting Problem Statement - RFC 3132 • Requirements and Functional Architecture for an IP Mobile Node Alerting Protocol - RFC 3154 • Problem Description: Reasons For Performing Context Transfers Between Nodes in an IP Access Network - RFC 3374• In Review • General Requirements for a Context Transfer • Issues in CAR Discovery for seamless IP-level handoffs • Requirements for CAR Discovery Protocols • Mobility Related Terminology• Under Discussion • Context Transfer Protocol • Candidate Access Router Discovery Protocol30 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  31. 31. Context Transfer Solutions • ICMP/UDP-based context transfer. • Efficient • Enables smoother handoffs. • Easily to integrate with MIP. • Well-known Transport Protocol (TCP / SCTP). • May need engineered access network (i.e. – cellular) • Applicable for more than just handoff signaling?31 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  32. 32. Mobile IPv6 with Context Trasfer • Current mobile IP (v4 or v6) specifications are not alone sufficient to construct a network that offers VoIP type of services (real time requirements, no packet loss) with mobile nodes changing their point of attachment frequently. • Smooth handover == low loss • Fast handover == low delay • Seamless handover == smooth and fast • Following things to transfer • header compression • buffer management • AAA / Security information • QoS sessions32 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  33. 33. Context Transfer Framework Public internet Home Agent Correspondent node CT Request CT Ack Previous Router New Router33 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  34. 34. The Future? • What do we see that is useful for SeaMoby to solve? • Smooth, seamless Mobile VoIP. • Inter-technology handovers. • Operator – ISP handovers (Cellular – WLAN handovers). • Adding additional IP technology to ‘existing’ cellular architecture.34 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  35. 35. Next Steps In Signaling • Work on a next generation signaling protocol. • Re-use good parts of RSVP, while optimizing it (RSVP is used heavily in MPLS signaling.) • Make the signaling protocol generic, to support multiple services. • Useful for signaling entities along the data path (NATs, firewalls, resource entities, etc.)35 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  36. 36. Main Ideas • Decouple (QoS) signaling (i.e. – requesting) from resource reservation. • Signal not just for QoS but for NAT traversal, Firewall pin-hole requesting, etc. • Resource reservation is increasingly seen as a network management issue. Some service providers will want to use contractual means for reserving bandwidth rather than protocol means.36 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  37. 37. NSIS Work Items • Under review • Requirements of a QoS Solution for Mobile IP • Requirements for Signaling Protocols • Being Discussed • Next Steps in Signaling: Framework • Security Threats for NSIS • RSVP Security Properties • Analysis of Existing Quality of Service Signaling Protocols • Soon to be Submitted • NSIS Transport Layer Protocol (NTLP) • NSIS Applications (QoS; Middle Box traversal)37 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  38. 38. How • Provide means for users to signal to edge network (end-to- edge). • Allow for edge-to-edge signaling, however this may not be always needed. • Application layer may wait until QoS requirements are fufilled before setting up sessions. • Goals • Transparent - don’t require uses to know / set-up too much. • Simple – allow service provides to provision / allocate resources as their business model calls for. • Extensible38 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  39. 39. Possible Uses • QoS • WLAN UNI for Requesting QoS into an IMS. • 3GPP2 QoS bearer • NNI protocol for GGSN-GGSN QoS reservations • Used with SIP QoS preconditions • General • NAT Traversal • Firewall Traversal • Gateway Traversal39 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney
  40. 40. Summary • Integrating different access technologies (3G, WLAN, DSL, Dial-up): • increases the potential for increasing subscribers. • increases accesses to services. • Integrating/harmonizing signaling: • harmonizes network infrastructure. • simplifies network management. • simplifies charging/billing. • simplifies the user experience.40 © NOKIA SIP&ALL-IP.PPT/ 29 April 2003 / John A. Loughney

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