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Presentation on theme: " VON Europe 2000 - 06-19-00 SIP Update Jonathan Rosenberg Chief Scientist co-chair, IETF SIP Working Group."— Presentation transcript:


2 VON Europe SIP Update Jonathan Rosenberg Chief Scientist co-chair, IETF SIP Working Group

3 VON Europe SIP Update Summary of SIP WG Status Nearly 200 Attendees at IETF 47 in Adelaide, Australia, March Active Internet Drafts Nearly 20 Documents As Agreed Upon Work Items Half a Dozen Design Teams Focusing on Specific Documents Most Deliverables Before 2001

4 VON Europe SIP Update Management and Auto-configuration SIP MIB Management of proxy, redirect, registrar and user agents Based on existing MIBs in existing boxes Initial draft defines extensive monitoring capabilities Traps and configuration need to be done Expected completion end of 2000 DHCP Option for SIP Servers User agent can learn where to register and where to send requests Use existing DHCP servers Draft currently under IESG review for RFC

5 VON Europe SIP Update Management and Autoconfiguration cont. Service Location Protocol (SLP) Templates SLP allows clients to discover servers based on capabilities SLP template for SIP allows discovery of SIP servers based on capabilities IPSec and TLS transports CPL support Support for caller preferences Has already been registered with IANA

6 VON Europe SIP Update Originally Developed by ISC Inter-softswitch communications ISUP transparency Now a SIP Working Group Item INFO method extension Mid-call ISUP messages Under IESG review ISUP to SIP message conversions MIME payload type for ISUP Nearing completion Umbrella specification SIP-T MGC SCTP Megaco T1 SS7 SIP-T SCTP Megaco T1 SS7 SG MGC SG Proxy Server

7 VON Europe SIP Update Infrastructure Improvements Reliability of Provisional Responses SIP Provisional responses are not currently reliable Convey ringing and call queue status PSTN interoperability mandates these be reliable Extension allows them to be retransmitted and acknowledged Specification currently in IETF working group last call

8 VON Europe SIP Update Infrastructure Improvements cont. Session Timer SIP has no end-to-end keepalive for an active session This is needed for several applications NAT/firewall traversal Billing Session timer allows session to be periodically refreshed Can even recover from end system crash Completion near end of June 2000

9 VON Europe SIP Update SIP Caller Preferences SIP Extensions for Specifying Caller Preferences and Callee State Presence! Preferences Carried in INVITE Setup Message Preferences for Reaching callee at home or work Fax, video, audio call Mobile or landline Secretary or voic Priority locations Expected Completion July 2000 Preference Video Proxy Server

10 VON Europe SIP Update SIP and QoS Problem Resource reservation and call signaling are separate Call setup needed to obtain IP addresses for reservation Call setup can succeed, while Reservation Fails Solution Couple resource reservation and signaling at end system Define general pre-conditions to session establishment COMET method indicates conditions are met INV 183 Progress PRACK CallerCallee 200 OK ACK Resource Reservation Ringing Pickup Media COMET

11 VON Europe SIP Update State Mechanism HTTP Supports Notion of Cookies Data passed from server to client Client passes data back to server in subsequent requests Cookie content opaque to client Cookies Provide Many Benefits Session management Fault tolerance Scalability Define the Same in SIP Passed from proxies to UA Passed back in subsequent requests for same call INVITE 200 OK State: Proxy1 foo, Proxy2 bar BYE State: Proxy1 foo, Proxy2 bar Proxy Server

12 VON Europe SIP Update Third Party Call Control Many Services Require Network Entity to Create Calls Between Pairs of Users or Services IVR services Click to dial Prepaid calling Third Party Call Control Mechanism Allows a User Agent to Do This Not a SIP extension at all Manipulates SDP in SIP messages so that media flows between users INVITE no SDP 200 ACK INVITE SDP (2) 200 ACK Application Server RTP

13 VON Europe SIP Update Firewall and NAT Traversal Need for Secure Traversal of SIP and Its Signaled Sessions Through NAT and Firewall SIP is a Session Control Protocol IP address and ports appear in body of protocol Fundamental to SIP operation Bad for NAT traversal SIP NAT ALG Needed But, Embedding ALG in NAT is Not Good Scaling Separation of function Expertise issue

14 VON Europe SIP Update Proposed Solution Separate Application Layer NAT/Firewall from IP Layer NAT/Firewall Have Application Specific Devices (Proxies) Perform Application Layer NAT Expertise problem solved Separation of function - enables growth Scaling much better Use application layer load balancing techniques IP NAT only box can be fast SIP Control RTP Proxy Server Firewall/NAT

15 VON Europe SIP Update IETF Efforts on Firewall Traversal SIP Working Group Informational RFC will be developed Summarizes SIP operations needed in firewall controlling proxy Discusses problems and issues Call flows and examples FOGLAMPS BoF Session Pre-Working Group Looking at developing the protocol between firewall controlling proxy and firewall Currently working on requirements for this protocol

16 VON Europe SIP Update The Missing Piece Control Protocol Between SIP ALG and IP NAT/Firewall Main Requirements Binding request: give a private address, obtain a public address Binding release Open Hole (firewall) Close hole (firewall) Group bindings INVITE BIND REQ BINDING INVITE 200 OK OPEN ACK Proxy Server Firewall

17 VON Europe SIP Update Information Resource Jonathan Rosenberg

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