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

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 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, x, 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 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 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 b DNS LDAP MIP MIP-LR CIP SDP MIPv6 MGCP IDMP IETF Multimedia Protocol Stack DHCPP Heterogeneous Access

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

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 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  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 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 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 Heterogeneous Access for Services in a LAN (SIP and Mobile IP approach) CDMA xWaveLan 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 IPS x

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 x Public Internet Public SIP Server Router AAA

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 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 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 b Outer sphere CDMA/CDPD network SIP Proxy MH DMZ Network CH SIP Proxy Cisco’s NAT CH MH SIP Client DMZ Network SIP based Heterogeneous Mobility (802.11b and CDMA1xRTT)

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, b  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 b 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 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 b driver issue)  In case of simultaneous bindings active IP address detection can be policy based