Multimedia SIP Sessions in a Mobile Heterogeneous Access Environment

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

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Outline

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

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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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Wireless Internet Roaming in Heterogeneous
Environment
Domain1
Internet
Domain2
S4
AN
Access Network 3
S3
S1
Access Network
S2
Access Network 1
Access Network 2
Cellular Network
Access Network
Access Network
SIP UA
PAN
Multi-media Terminal
SIP UA
Webphone
PDA
SIP UA
Cellular Network
WLAN Network
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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
Ethernet
802.11b
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
• siponur_at_toyota-itc.com

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

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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)

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SIP Mobility Basic Flows
CH
MH
SIP server
MH (new location)
Register
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
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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
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Heterogeneous Access for Services in a LAN (SIP
and Mobile IP approach)
Home Agent
Internet
CH/ Media Server
Home Network
SIP UA
Visited Network B
Visited Network A
DHCP
SIP Server
PPP Server
PPP Server
Intra-Net
SIP Server
DHCP
Router/ Foreign Agent
Router/ Foreign agent
Subnet S1
Subnet S0
Intra-Subnet Mobility
CDMA
Bluetooth
802.11x
CDMA
802.11x
WaveLan
Bluetooth
IPS13
IPS01
IPS11
IPS12
IPS02
IPS03
Inter -Subnet Mobility
SIP UA
SIP UA
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Heterogeneous Access for SIP Sessions
Home SIP Server
CH
IPch
Core Network
Public Internet
Core Network
Core Network
AAA
Public SIP Server
DHCP /PPP
DHCP
WLAN Access Network
CDMA/GPRS
MH
Cellular Access Network
802.11x
IPA1
IPB1
DHCP/ PPP
DHCP
Router
Router
CDMA/GPRS
802.11x
Local SIP Server
IPB2
Local SIP Server
IPA2
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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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SIP based Heterogeneous Mobility (802.11b and
CDMA1xRTT)
Outer sphere CDMA/CDPD network
DMZ Network
Company Intranet
DomainSN1
DHCP
HUB
IGW
Ciscos NAT
DNS
Internet
CH
sun80
SIP Client
cisco80
PPP Server/ Wireless ISP
.21
DomainSN2
SIP Proxy
802.11b
DHCP
SIP Proxy
Private Subnet 2
MH
CH
sun90
CDMA
CDPD
cisco90
DHCP
DomainSN3
802.11b
Private Subnet 1
Private Subnet 3
802.11b
Outdoor
DMZ Network 802.11
MH
SIP Client
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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