The Internet Real-Time
Laboratory
Henning Schulzrinne
April 2002
http://www.cs.columbia.edu/IRT
Networking research at
Columbia University






Columbia Networking Research
Center
spans EE + CS
15 faculty – one of the largest
networking research groups in the
US
about 40 PhDs
spanning optical networks to
operating systems and applications
theory (performance analysis) to
systems (software, protocols)
Laboratory overview


Dept. of Computer Science: 30 faculty
IRT lab: 12 PhD students





4 at IBM, Juniper, Lucent, Telcordia
5 MS GRAs
5 visitors (Ericsson, Fujitsu, Mitsubishi, Nokia,
U. Coimbra)
China, Finland, Greece, India, Japan,
Portugal, Spain, Sweden, US, Taiwan
15 MS and undergraduate project students
Laboratory support
Equipment grants and student support
IRT topics

Internet multimedia protocols and systems




Internet telephony and radio (J. Lennox, X. Wu, K.
Singh, K. Arabshian, W. Jiang, J. Rosenberg, A.
Dutta, K. Koguchi; K. Butler, A. Nambi, S.
Narayanan, A. Khwaja, S. Sridhar)
Content distribution networks (L. Amini, Y.
Nomura)
Internet event distribution (P. Koskelainen)
Wireless ad-hoc networks (M. Papadopouli, S.
Sidiroglou)
IRT topics

Quality of service


Pricing for adaptive services (RNAP) (X.
Wang)
Scalable resource reservation protocols (P.
Pan)


BGRP for aggregation, YESSIR for applications
Fair multicast resource allocation (P.
Mendes)
IP telephony: QoS estimation

QoS estimation of voice traffic




influence of loss correlation + FEC
estimation via objective methods
automated MOS estimation via speech
recognition
Planning: tools for automated end-toend assessment
CINEMA

Web interface




Administration
User configuration
Unified Messaging
 Notify by email
 rtsp or http
Portal Mode

3rd party IpTelSP
CINEMA components
Cisco 7960
MySQL
sipconf
user database
rtspd
LDAP server
conferencing
server
(MCU)
sipd
RTSP
media
server
RTSP
proxy/redirect server
unified
messaging
server
Pingtel
Nortel
Meridian
Cisco
2600
sipum
VoiceXML
server
PBX
T1
T1
SIP
sipvxml
PhoneJack interface
sipc
SIP-H.323
converter
sip-h323
plug'n'sip
wireless
802.11b
CINEMA

Goal: fully integrated communications
platform:





synchronous + asynchronous collaboration
calendaring
multimedia collaboration: G.711 and highquality audio, video, shared whiteboard,
chat, shared applications
Web control or VoiceXML interaction
support pure VoIP and hybrids
Internet telephony: sipc

Cross-platform tool for integrated multimedia
communications









Windows 98/NT/2K/XP
Solaris, Linux, FreeBSD
Support media plug-ins
Screen sharing
IM and presence
programmable logic (cgi, CPL)
Device control (electric appliances)
(Emergency) notification
Conference control (in progress)
PSTN interworking
PSTN
External T1/CAS
1 Call 9397134
Nortel PBX
Internal T1/CAS
(Ext:7130-7139)
2
Gateway
Call 7134
Ethernet
5551212
Regular phone
(internal)
5
3
SIP server
sipc
Bob’s phone
SQL
database
sipd
4
7134 => bob
Internet telephony:
emergency communications


911
services
architecture
emergency
notification
EPAD
302 Moved
Contact: sip:sos@psap.leonia.nj.us
Contact: tel:+1-201-911-1234
REGISTER sip:sos
Location: 07605
INVITE sip:sos
Location: 07605
SIP
proxy
Languages for service creation




Traditionally, telecom services created
by switch vendors
Web model: allow users and
organizations to create custom services
Two models: sip-cgi and CPL
Sip-cgi: cgi scripts for call handling logic
Internet telephony: APIs



APIs for IM and presence (JAIN JSR)
design and implementation
cooperation with Panasonic
Call Processing Language

XML-based language
<incoming>
<address-switch field="origin" subfield="host">
<address subdomain-of="example.com">
<location url="sip:jones@example.com">
<proxy>
<busy> <sub ref="voicemail" /> </busy>
<noanswer> <sub ref="voicemail" /> </noanswer>
<failure> <sub ref="voicemail" /> </failure>
</proxy>
</location>
</address>
<otherwise>
<sub ref="voicemail" />
</otherwise>
</address-switch>
</incoming>
Mobile ad-hoc networks: 7DS



Wireless infrastructure slow to emerge
(Metricom , 3G $$$)
802.11b cheap and simple to deploy
Mobile devices spread data in densely
populated areas (e.g., NYC)
7DS




Content-independent: works for any
web object
Uses standard caching mechanism
After 25’, 90% of interested users have
2
data (25 hosts/km )
Also, data upload:
Ad-hoc wireless infrastructure
7DS research issues

Effects of power conservation, collaboration
mechanism, wireless coverage range, density
of devices on information dissemination


e.g., how fast does information
spread in such setting ? what is the
average delay that a host experience
until it gets the data ?
Performance analysis via simulations and
diffusion controlled processes theory
Fairness for multicast
Differentiated Service (DiffServ) networks divide
traffic into different service quality levels,
considering their quality requirements:
 Intolerant (loss&delay) applications will use
DiffServ Premium services, while tolerant
applications can use Assured services;
 Multimedia flows multicast to heterogeneous
receivers will use Assured services;
 Problem: Resources aren’t fairly distributed
between flows inside a DiffServ service.
Multi-receiver fair allocation
Provide fair distribution of Assured services
resources between multimedia multicast flows
considering:




The number of receivers in each multicast flow;
A maximal utilization of resources;
Differential dropping between flows that overpass
their share of service resources;
A Multi-Receiver Utilization Maximal fair mechanism
(MRUM) is being developed.
Quality of service: pricing

Bandwidth: decrease of marginal
returns adaptive services
U1
U2
U3
Cost
Budget
Bandwidth
Bandwidth pricing

Congestion pricing





See GWB, turnpike, electricity
Higher overall utility
Prices constant for periods O(min)
Auction or tatonnement pricing
Charge for usage and reservation
Service location

Enhancements to Service Location
Protocol (SLP):



reliability and scaling (meshed SLP)
remote discovery
attributes
Summary and future plans







Personal and session mobility
Service creation for VoIP
Integrating the natural environment into IP
communications
Conferencing and conference control
Ad-hoc and hybrid ad-hoc/infrastructure
networks
Emergency communications
Network reliability