Multimedia SIP Sessions in a Mobile Heterogeneous Access Environment

Ashutosh Dutta, Yibei Ling, Wai Chen, Jasmine ChennikaraTelcordia 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

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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

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WLAN Network

AccessNetwork 2

AccessNetwork 3

CellularNetwork

S1

S2

S3

S4

AccessNetwork

AccessNetwork

AccessNetwork

CellularNetwork

InternetDomain1

Domain2

PDA

Webphone

Multi-mediaTerminal

AN

AccessNetwork 1

Wireless Internet Roaming in Heterogeneous Environment

SIP UA

SIP UA

SIP UA

PAN

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Media Transport

App

lica

tion

Dae

mon

Ker

nel

Phy

sica

lN

etw

ork

H.323 SIP RTSP RSVP RTCPRTP

TCP UDP

IPv4, IPv6, IP Multicast

PPP AAL3/4 AAL5 PPP

SONET ATM Ethernet CDMA 1XRTT/GPRS

Signaling media encap(H.261. MPEG)

ICMP IGMP

SAP

802.11b

DNSLDAP

MIP MIP-LR

CIP

SDP

MIPv6

MGCP

IDMP

IETF Multimedia Protocol Stack

DHCPP

Heterogeneous Access

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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

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SIP Background: Components

SIP server Registrar

Proxy

LocationDatabase

Redirect

Proxy

SIP User Agent Client Host

SIP User Agent Client

SIP User Agent ServerHost

SIP User Agent Server

UDP/5060 (Signaling)

UDP/5060 (Signaling)

RAT

WB

VIC

CHAT

VNC

RAT

WB

VIC

CHAT

VNC

audio

video

white board

text

desktop sharing

RTP/UDP

RTCP

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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

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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

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SIP Mobility Basic Flows

CH MH 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

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Handoff Delay Analysis (SIP-Mobility)

CH MH (IP0)SIP Signaling

RTP Session

Base StationMH (IP1)

MH movesBeacon

DHCP/PPP Server

Discover/Request

Offer/IP address

Binds L2

L3

Configuration Time

Re-Invite

RTP SessionMedia

Redirection

Beacon Interval

Beacon

L2 = Layer 2

L3 = Layer 3

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Heterogeneous Access for Services in a LAN (SIP and Mobile IP approach)

CDMA 802.11x WaveLan

DHCPDHCP

Internet

Subnet S0 Subnet S1

IPS01 IPS02 IPS11 IPS12

CH/Media Server

SIPServer

SIPServer

SIPUA

SIPUA

PPPServer

PPPServer

Bluetooth CDMABluetooth

Visited Network A Visited Network B

Home Network

Intra-Net

HomeAgent

Router/Foreign agent

Router/Foreign Agent

SIPUA

Intra-Subnet MobilityIntra-Subnet Mobility

Inter -Subnet MobilityInter -Subnet Mobility

IPS03IPS13

802.11x

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Heterogeneous Access for SIP Sessions

CDMA/GPRS

CDMA/GPRS

MHCellularAccess

Network

WLANAccess

Network

CH

LocalSIPServer

DHCP/PPP

DHCP/PPP

DHCP

DHCP

IPA1

IPA2

IPB1

IPB2 LocalSIPServer

IPch

CoreNetwork

CoreNetwork

HomeSIPServer

CoreNetwork

802.11x

802.11x

Public Internet

Public SIPServer

RouterRouter

AAA

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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)

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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

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DNS

DHCP

DHCP

DHCP

“Outdoor”

sun90

sun80.21

Domain:SN1

Domain:SN2

Domain:SN3

cisco80

cisco90

CompanyIntranet

InternetIGW

HUB

Private Subnet 1

Private Subnet 2

Private Subnet 3

PPP Server/Wireless ISP

CDMACDPD

802.11b

802.11b

802.11b

Outer sphereCDMA/CDPD network

SIP Proxy

MH

DMZ Network

CH

SIP Proxy

Cisco’s NAT

CH

MHSIP Client

SIP Client

DMZ Network802.11

SIP based Heterogeneous Mobility (802.11b and CDMA1xRTT)

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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)

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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