The Internet Real-Time Laboratory (IRT)

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The Internet Real-Time Laboratory (IRT)

• http//www.cs.columbia.edu/IRT
• Prof. Henning Schulzrinne
• Dept. of Computer Science
• Columbia University
• New York, NY
• January 2006

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Networking research at Columbia University

• Columbia Networking Research Center
• both Electrical Engineering Computer Science
  Department
• 13 faculty one of the largest networking
  research groups in the US
• about 40 PhD students
• spanning optical networks and wireless channels
  to operating systems, security and applications
• theory (performance analysis) to systems
  (software, protocols)

Steve Bellovin Keren Bergman Ed Coffman Predrag
Jelenkovic Angelos Keromytis Aurel Lazar Nick
Maxemchuk Vishal Misra Jason Nieh Dan
Rubenstein Henning Schulzrinne Xiaodong
Wang Yechiam Yemini
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Laboratory overview

• Dept. of Computer Science 35 faculty
• IRT lab staff
• 1 post-doc, 3 researchers
• 10 PhD students
• 7 MS GRAs
• visitors (Ericsson, Fujitsu, Mitsubishi, Nokia,
  U. Coimbra, U. Rome, NTT, )
• China, Finland, Greece, India, Japan, Portugal,
  Spain, Sweden, US, Taiwan
• 10 MS and undergraduate project students

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Laboratory support

• Equipment grants and student support

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Overall IRT lab goals

• Reliable, flexible and programmable communication
  infrastructure for Internet-based collaboration
  applications
• Systematic evaluation by analysis and simulation
• Demonstrate capability via prototypes
• Contribute protocols to standardization (IETF)
• Convert prototypes into products and open-source
  software
• Train students at all levels in current Internet
  research and engineering

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IRT research topics

• Internet telephony and multimedia
• CINEMA VoIP/multimedia and collaboration system
• QoS measurements
• network application reliability
• performance and server architecture
• APIs for SIP IM and presence systems
• ubiquitous computing using SIP
• application sharing
• P2P SIP systems
• emergency services (911)
• SIP security
• reputation systems, spam
• firewalls
• service creation languages
• CPL
• LESS

• Mobile and wireless systems
• 802.11 handoff acceleration
• 802.11 VoIP performance improvements
• SIP-based terminal mobility
• personal, service and session mobility
• Peer-to-peer messaging ? 7DS
• Service and event discovery (GloServ)
• Generic signaling protocols (GIMPS) for QoS,
  NAT/FW,
• Autonomic computing
• service discovery ? mSLP
• automated server pooling ? DotSlash

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IRT and standards

• PI and researchers active in IETF since 1992
• RTP lead author
• RTSP lead author
• SIP original design core team
• SIP mobility
• rich presence
• privacy and geo-services
• emergency calling
• SLP extensions for scalability
• GIST network signaling protocol

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Graduated PhD students

• Internet telephony services, GSM interoperation
  (J. Lennox)
• QoS and reliability measurements (W. Jiang)
• Federated CDNs (L. Amini)
• Pricing for QoS, LDAP performance (X. Wang)
• Multicast QoS fairness signaling (P. Mendes)
• Internet telephony topics (J. Rosenberg)
• Mobile peer-to-peer systems (M. Papadopouli)
• Scalable resource reservation (P. Pan)
• VoIP service creation (J. Lennox)

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Multimedia systems problems

• Old problems and approaches
• efficient codecs
• ubiquitous reachability
• audio/video synchronization
• network-layer mobility
• quality-of-service
• APIs and middleware

• New problems
• controlled reachability
• spam
• cell phone ringing in lecture
• service availability
• information privacy
• service personal mobility
• service creation by non-experts

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CINEMA components
Cisco 7960
MySQL
rtspd
sipconf
user database
LDAP server
plug'n'sip
RTSP
conferencing
media
server
server
(MCU)
wireless
sipd
802.11b
RTSP
proxy/redirect server
unified
messaging
server
Pingtel
sipum
Cisco
Nortel
2600
Meridian
VoiceXML
PBX
server
T1
T1
SIP
sipvxml
PhoneJack interface
sipc
SIP-H.323
converter
sip-h323
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SIP emergency calling
GPS
INVITE sipssos_at_
48 49' N 2 29' E
outbound proxy server
DHCP
48 49' N 2 29' E ? Paris fire department
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SIP for ubiquitous computing

• Focus on inter-domain, scalable systems
• Components
• context-aware communications
• context-aware service and event discovery
• location-based services
• global-scale event notification
• service creation by end users
• terminal, personal, session and service mobility

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Context-aware communication

• context the interrelated conditions in which
  something exists or occurs
• anything known about the participants in the
  (potential) communication relationship
• both at caller and callee

time CPL
capabilities caller preferences
location location-based call routing location events
activity/availability rich presence
sensor data (mood, bio) not yet, but similar in many aspects to location data
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RPIDS rich presence data

• Basic IETF presence (CPIM) only gives you
• contact information (SIP, tel URI)
• priority
• open or closed
• Extend to much richer context information

watcher
everything
PA
PUA
watcher
"vague"
PUBLISH
watcher
NOTIFY
CPL
INVITE
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Session mobility

• Walk into office, switch from cell phone to desk
  phone
• call transfer problem ? SIP REFER
• related problem split session across end devices
• e.g., wall display desk phone PC for
  collaborative application
• assume devices (or stand-ins) are SIP-enabled
• third-party call control

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Service mobility user-adaptive device
configuration
all devices that are in the building RFC 3082?
SLP
802.11 signal strength ? location
device controller
REGISTER To 815cepsr Contact alice_at_cs
PA
HTTP
SUBSCRIBE to each room
tftp

1. discover room URI
2. REGISTER as contact for room URI

SIP
SUBSCRIBE to configuration for users currently in
rooms
room 815
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Location-based services

• Presence-based approach
• UA publishes location to presence agent (PA)
• becomes part of general user context
• other users (human and machines) subscribe to
  context
• call handling and direction
• location-based anycast (anybody in the room)
• location-based service directory
• Languages for location-based services
• building on experience with our XML-based service
  creation languages
• CPL for user-location services
• LESS for end system services

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Location-based IM presence
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Service creation

• Promise of faster service creation
• traditionally, only vendors (and sometimes
  carriers)
• learn from web models

programmer, carrier end user
network servers SIP servlets, sip-cgi CPL
end system VoiceXML VoiceXML (voice), LESS
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Service creation environment for CPL and LESS
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GloServ Hierarchical P2P Global Service
Discovery Architecture Knarig Arabshian and
Henning Schulzrinne

• Classify services using OWL
• Use service classification to map ontology to a
  hierarchical P2P network (using CAN for p2p)
• Bootstrap servers using information in ontology
• Intelligent registration and querying

hasActivity
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QoS in VoIP Wireless Networks Adaptive Priority
Control (APC)

• Unbalanced uplink and downlink delay due to
  fairness in DCF.
• Uplink and downlink delay need to be balanced for
  better QoS and capacity for VoIP.
• AP needs to have a higher priority than the
  wireless nodes for fairness between uplink and
  downlink.

Capacity

• Adaptive Priority Control
• Decides the priority of the AP adaptively based
  on
• Wireless channel condition
• Uplink and downlink traffic volume
• Controls the transmission rate of the AP
  according to the priority of the AP using Content
  Free Transmission.
• No changes in wireless nodes

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Accelerating DHCP P-DAD
Address Usage Collector (AUC)
DHCP server
TCP Connection
Broadcast-ARP/DHCP
Router/Relay Agent
SUBNET

• AUC builds DUIDMAC pair table (DHCP traffic
  only)
• AUC builds IPMAC pair table (broadcast and ARP
  traffic)
• New pair is added to table, unauthorized IP
  detected ? AUC sends pair to DHCP server
• DHCP server checks if pair is correct and records
  IP address as in use
• ARP checking
• AUC scans unused IPs using ARP query periodically
• Silent nodes can be detected

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Ad-hoc wireless infrastructure
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./ Rescue service for web servers experiencing
15 minutes of fame
Extend Apache mod_dots, dotsd, DNS, mSLP
State Transition
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Conclusion

• Other topics
• Skype analysis, QoS signaling, QoS for
  voice-over-802.11
• Focus on Internet multimedia services
• fixed mobile applications
• VoIP protocols, presence, location-based
  services, service creation, p2p networks
• QoS in networks
• Protocols, prototypes, performance evaluation