Optimized Fast-handoff Scheme for Application Layer Mobility Management

1. Optimized Fast-handoff Scheme for Application Layer Mobility Management Authors: Ashutosh Dutta, Sunil Madhani, Wai Chen Telcordia Technologies Henning Schulzrinne Columbia University Onur Altintas Toyota InfoTechnology Center [First author is also a student at Columbia University]

2. Outline • Motivation • Intra-domain Mobility Management • SIP based Mobility Management • SIP and Mobile IP • Fast-handoff for SIP Mobility • Test-bed Realization • Experimental results

3. IETF Multimedia Protocol Stack Media Transport media encap (H.261. MPEG) Signaling SAP SDP MGCP DHCPP Application Daemon SIP H.323 RTSP RSVP RTCP RTP DNS LDAP TCP UDP CIP MIPv6 IDMP Network MIP ICMP IGMP MIP-LR IPv4, IPv6, IP Multicast Kernel PPP AAL3/4 AAL5 PPP Physical CDMA 1XRTT /GPRS SONET ATM 802.11b Ethernet Heterogeneous Access

4. Motivation • Objective: Design and evaluate optimized techniques based on Application Layer Mobility Management Scheme • Several Network Layer Scheme provide optimized handoff techniques for Intra-domain mobility • Application Layer Mobility Management Scheme rules out the need for networking components such as Home Agent/Foreign Agent • SIP based mobility is an application layer scheme supporting Real-Time traffic for Mobile Wireless Internet • It is essential to reduce transient real-time traffic during frequent handoffs

5. Network Layer fast-handoff approaches • Intra-domain Mobility Management Protocol • Use of Mobility Agent to limit the Intra-domain updates to within a domain • Hierarchical Mobile IPv4/v6 Fast Hand-offs • Foreign Agent Assisted Handoffs • Intra-domain Mobility with buffering Agents

6. SIP Background • SIP allows two or more participants to establish a session including multiple media streams • audio, video, distributed games, shared applications, white boards, or any other Internet-based communication mechanism • Standardized by the IETF RFC 2543 • Is being implemented by several vendors, primarily for Internet telephony • e.g. Microsoft XP operating system includes SIP as part of its built-in protocol stack • Recently being extended to provide presence, instant messaging and event notification • Endpoints addressed by SIP URLs • sip:onur@toyota-itc.com

7. Why SIP Mobility ? • SIP is an application layer signaling protocol: • it can keep mobility support independent of the underlying wireless technology and network layer elements; • 3GPP, 3GPP2, and MWIF have agreed upon SIP as the basis of the session management of the mobile Internet • SIP will eventually be part of the mobile Internet so why not use its inherently present mobility support functions • SIP can provide personal mobility, terminal mobility, session mobility and service mobility • No requirement to modify (or add) capabilities to existing terminal’s operating system

8. Types of SIP mobility • SIP provides variety of mobility techniques • Personal Mobility • Allows users to be reachable in multiple locations using a unique URI • Service Mobility • Allows users to maintain access to their services while moving between service providers • Session Mobility • Allows a user to maintain a media session while changing between terminals • Mid-session (terminal) mobility • Allows a user to maintain a session while moving (support for real-time streaming applications for mobiles)

9. SIP mobility Performance snapshot in 802.11 Environment Byte Sizes of SIP signaling Timing for Signaling messages • INVITE - 455 bytes 100 msec processing time between msgs (OS dependent) • Ringing - 223 bytes 5 msec for Invite to traverse • OK - 381 bytes 70 msec for Re-Invite to traverse (mostly queuing delays) • ACK - 261 bytes 150 msec for complete re-registration • Bye - 150 bytes 300-400 msec for address acquisition without (SIP,MIP) • De-Register - 370 bytes 3-4 sec for address acquisition with ARP (SIP,MIP) • Re-Invite - 450 bytes • Re-register - 425 bytes

10. Handoff Delay Analysis (SIP-Mobility) MH (IP1) CH MH (IP0) Base Station DHCP/PPP Server SIP Signaling Beacon Beacon Interval RTP Session MH moves Beacon Binds L2 Discover/Request L3 Offer/IP address Configuration Time Re-Invite L2 = Layer 2 Media Redirection RTP Session L3 = Layer 3

11. SIP vs. MIP Latency (Experiment) SIP vs MIP Utilization Gain (Experiment) 40 27 msec 35 ~50% latency improvement 0.5 30 25 SIP B/W Gain Latency in msec 0.4 SIP 20 16 msec MIP SIP B/W Gain 15 0.3 10 5 0.2 0 100 200 300 400 500 600 700 800 900 1000 1100 0 100 200 300 400 500 600 700 800 900 1000 1100 Packet Size in bytes Bytes per packet SIPMM-MIP BW and Latency experimental evaluation

12. CIP update MIP registration Gateway B Gateway A Cellular IP Node Cellular IP Node Cellular IP Node Cellular IP Node CIP Node CIP Node CIP Node CIP Node CIP Node CIP Node CIP Node CIP Node Media Cellular IP Home Agent Correspondent Host Internet (with Mobile IP) Domain B Domain A

13. Hierarchical Foreign Agent

14. HAWAII Internet Domain 2 Domain 1 Domain Root Router Domain Root Router R R R R R R R R R BS BS BS

15. IDMP/TeleMIP Architecture TeleMIP’s Architecture Layout

16. Initial Domain-Based Registration Procedure

17. Subsequent Intra-Domain Registration

18. Mobility Proxy

19. CH MH MH MH SIP fast-handoff mechanism -RTPtrans Intra- Domain fast-handoff Domain -D1 RT1,RT2,RT3 - RTP Translators Mapping Database IP2 -> IPR1 Delay IP3 -> IPR2 Simulator . SIP . Server . (Media) R 1 2 (Re-invite) (Media in flight) 3 Register 2’ IPR2 IPR3 IPR1 4 RT3 RT2 RT1 IP2:p1 IP1:p1 4’ (Transient media) IP1 IP3 IP2

20. SIP fast-handoff RTPtrans - Protocol flow

21. MH MH MH SIP fast-handoff with B2B SIP UA – approach 1 Delay Router CH Simulator IPch SIP MA (B2B) Media Invite B2B SDP SIP SIP UAC UAS SIP SIP Media UAS UAC Media Media Media Invite Re-Invite Invite IP3 IP2 IP1(Initial position before move) Move

22. Flow diagram B2B approach –1(Limits Re-invite to B2B UA within a domain) IP1 B2BUA IP0 UA1 UA2 MH MH CH Invite Invite ok ok ack ack RTP1 RTP2 Media Transl- ator Re-Invite RTP1 after the move RTP2

23. MH MH MH SIP fast-handoff with B2B SIP UA – approach 2 Delay Router CH Simulator IPch SIP MA (B2B) Invite MH SDP SIP SIP UAC UAS SIP SIP Media UAS UAC Media Media Invite Invite no SDP Invite IP3 IP2 IP1(Initial position before move) Move

24. Fast handoff with B2B UA – approach 2 – flow diagram Re-invite from MH activates the interceptor at B2BUA IP1 IP0 B2BUA MH MH UA1 UA2 CH Invite (no SDP) OK (MH SDP) Invite MH SDP OK ACK ACK CH SDP RTP Re-Invite RTP1 (Interceptor)

25. B2BUA- fast-handoff – approach 3 multicast agent

26. B2BUA- fast-handoff – approach 3 multicast agent -flow B2BUA IP1 IP0 CH MH MH UA1 UA2 Invite (no SDP) OK (MH SDP) Invite MH SDP OK ACK ACK CH SDP RTP Re-Invite Re-Invite with Maddr Transient data at M addr RTP1 RTP

27. SIP based Mobility in a Test-bed Outer sphere CDMA/CDPD network DMZ Network Company Intranet Domain:SN1 DHCP HUB IGW Cisco’s NAT DNS Internet CH sun80 SIP Client cisco80 PPP Server/ Wireless ISP .21 Domain:SN2 SIP Proxy 802.11b DHCP SIP Proxy MH Private Subnet 2 CH sun90 CDMA CDPD cisco90 Domain:SN3 DHCP 802.11b Private Subnet 3 Private Subnet 1 802.11b “Outdoor” DMZ Network 802.11 MH SIP Client

28. Sample Packet Trace for Fast Handoff (see notes page)

29. Sample Packet Trace for Mobility Proxy-based Handoff (see notes page)

30. Issues • Duplicate Packets Detection • Aging of RTP translator • Scalability • Number of subnets is large • Mobile is moving too rapidly between the subnets • Mechanism to remove the virtual Interface • Mapping of subnets and RTPtranslators

31. Conclusions • Application Layer fast-handoff mechanism discussed • Test-bed Realization presented • Results of the experiments analyzed • RTP aging, scalability, effect of mobility rate are future • Comparison with other network layer approaches is helpful.