1. Multimedia SIP Sessions in a Mobile Heterogeneous Access Environment Ashutosh Dutta, Yibei Ling, Wai Chen, Jasmine Chennikara Telcordia Technologies Onur Altıntaş Toyota InfoTechnology Center, USA Henning Schulzrinne Columbia University

2. 2 Outline  SIP based mobility  Heterogeneous Access Architecture  Issues related to SIP-based sessions  SIP sessions for Heterogeneous Networks  Experimental Setup and Results  Conclusions

3. 3 Motivation (1) Objective: Analyze and experiment with a carrier-independent end-to-end Mobility Solution for scalable wireless Internet Roaming involving PAN, LAN and WAN

4. 4 Motivation (2)  Wireless Internet Roaming is becoming a norm rather than an exception  SIP is gaining momentum as a signaling mechanism for multimedia sessions  SIP provides an application layer multi-facet mobility solution  Many drawbacks associated with Mobile IP are taken care of –No dependence on HA based solution  Multiple Access Technologies (Bluetooth, 802.11x, CDMA, GPRS) –Provide an integration between PAN, LAN and WAN –Flexibility of selecting a particular interface based on type of application  Smooth transition between heterogeneous access networks by providing a virtual soft-handover

5. 5 WLAN Network Access Network 2 Access Network 3 Cellular Network S1 S2 S3 S4 Access Network Access Network Access Network Cellular Network Internet Domain1 Domain2 PDA Web phone Multi-media Terminal AN Access Network 1 Wireless Internet Roaming in Heterogeneous Environment SIP UA PAN

6. 6 Media Transport Application Daemon Kernel Physical Network H.323 SIP RTSP RSVPRTCP RTP TCPUDP IPv4, IPv6, IP Multicast PPPAAL3/4AAL5PPP SONETATM Ethernet CDMA 1XRTT /GPRS Signaling media encap (H.261. MPEG) ICMPIGMP SAP 802.11b DNS LDAP MIP MIP-LR CIP SDP MIPv6 MGCP IDMP IETF Multimedia Protocol Stack DHCPP Heterogeneous Access

7. 7 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

8. 8 SIP Background: Components SIP server Registrar Proxy Location Database Redirect Proxy SIP User Agent Client Host SIP User Agent Client SIP User Agent Server Host SIP User Agent Server UDP/5060 (Signaling) RAT WB VIC CHAT VNC RAT WB VIC CHAT VNC audio video white board text desktop sharing RTP/UDP RTCP

9. 9 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

10. 10  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) Types of SIP mobility

11. 11 SIP Mobility Basic Flows CHMH MH (new location) SIP Signaling RTP Media stream MH moves during session Re-register Re-INVITE with new Contact address SIP signaling and RTP/UDP session remains intact SIP server Register

12. 12 Handoff Delay Analysis (SIP-Mobility) CH MH ( IP0 ) SIP Signaling RTP Session Base Station MH ( IP1 ) MH moves Beacon DHCP/PPP Server Discover/Request Offer/IP address BindsL2 L3 Configuration Time Re-Invite RTP Session Media Redirection Beacon Interval Beacon L2 = Layer 2 L3 = Layer 3

13. 13 Heterogeneous Access for Services in a LAN (SIP and Mobile IP approach) CDMA 802.11xWaveLan DHCP Internet Subnet S0 Subnet S1 IPS01 IPS02 IPS11IPS12 CH/ Media Server SIP Server SIP Server SIP UA SIP UA PPP Server PPP Server Bluetooth CDMA Bluetooth Visited Network A Visited Network B Home Network Intra-Net Home Agent Router/ Foreign agent Router/ Foreign Agent SIP UA Intra-Subnet Mobility Inter -Subnet Mobility IPS03 IPS13 802.11x

14. 14 Heterogeneous Access for SIP Sessions CDMA/GPRS MH Cellular Access Network WLAN Access Network CH Local SIP Server DHCP /PPP DHCP/ PPP DHCP IPA1 IPA2 IPB1 IPB2 Local SIP Server IP ch Core Network Core Network Home SIP Server Core Network 802.11x Public Internet Public SIP Server Router AAA

15. 15 Technical Issues (1)  Movement during session setup –With direct signaling  Retransmissions after timeout –With proxy server  Redirects to the right IP address  SIP sessions with NAT: IP address MH uses to invite CH will not reach MH (e.g. 3G network may be an Intranet) –Use of Application Layer Gateway –STUN (Simple Traversal of UDP through NAT)  User Agent with Multiple IP addresses detection –SNR based –Policy based –can be application specific (e.g. audio use CDMA, video use WLAN)

16. 16 Technical Issues (2)  Multiple IP registrations –Register the active IP address –Forking proxy  De-Register with the previous SIP server once the active interface changes –Public SIP servers can be used with proper security association  Proper Triggering Mechanism to change active interface –Channel change, –QoS of traffic, –server based, –L3 router solicitation

17. 17 DNS DHCP “Outdoor” sun90 sun80.21 Domain:SN1 Domain:SN2 Domain:SN3 cisco80 cisco90 Company Intranet Internet IGW HUB Private Subnet 1 Private Subnet 2 Private Subnet 3 PPP Server/ Wireless ISP CDMA CDPD 802.11b Outer sphere CDMA/CDPD network SIP Proxy MH DMZ Network CH SIP Proxy Cisco’s NAT CH MH SIP Client DMZ Network 802.11 SIP based Heterogeneous Mobility (802.11b and CDMA1xRTT)

18. 18 Experimental Setup and Results  Operating System –Windows XP and Linux  Multimedia Tools –RAT (Robust Audio Tool) for Audio,VIC (for Video)  Access Technologies –CDPD, CDMA1XRTT, 802.11b  Access hardware –Sierra Wireless 555, Kyocera 2235 with serial cable  End-to-end delay –450 msec using ping measurement over 1xRTT(16 hops) to Columbia Univ. –50 msec via 802.11b to Columbia Univ.  Throughput : –10-15 kbps on file transfer using TCP (Linux) - Indoor –25 Kbps on file transfer using TCP - outdoor –30 kbps video streaming using RTP (windows) - indoor, ~60 kbps outdoor  Handoff Latency including IP address acquisition –Switching from WLAN to CDMA (Linux ~ 10 sec ( PPP overhead ) (Windows ~ 20sec) –Switching from CDMA to WLAN (Linux ~ 5 sec ( ARP on )) (Windows ~15 sec)

19. 19 Conclusions  SIP based mobility for Heterogeneous Access Network has been realized in a test-bed for both indoor and outdoor network  It provides an end-to-end mobility solution without anything in the middle of the network such as home agent or Foreign Agent  It avoids triangular routing reducing the handoff delay  SIP based mobility is independent of L2 handoff and IP address acquisition issues  SIP mobility on Linux platform provides a faster handoff for real- time traffic compared to Windows XP ( probably a 802.11b driver issue)  In case of simultaneous bindings active IP address detection can be policy based