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The Internet Real-Time The Internet Real-Time LaboratoryLaboratory
Henning SchulzrinneSeptember 2003
http://www.cs.columbia.edu/IRT
Networking research at Networking research at Columbia UniversityColumbia 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 and
wireless channels to operating systems, security and applications
theory (performance analysis) to systems (software, protocols)
Laboratory overviewLaboratory overview Dept. of Computer Science: 32 faculty IRT lab: 13 PhD students
includes 3 part-time students working at IBM, Lucent, Telcordia
2 MS GRAs visitors (Ericsson, Fujitsu, Mitsubishi,
Nokia, U. Coimbra, U. Rome, NTT, …) China, Finland, Greece, India, Japan,
Portugal, Spain, Sweden, US, Taiwan ~15 MS and undergraduate project
students
IRT topicsIRT topics Internet multimedia protocols and
systems Internet telephony and radio (J. Lennox, X.
Wu, K. Singh, 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, K. Arabshian)
Wireless ad-hoc networks (M. Papadopouli, S. Sidiroglou)
IRT topicsIRT topics
Quality of service Pricing for adaptive services (RNAP)
(X. Wang) Scalable resource reservation
protocols (P. Pan) BGRP for aggregation, YESSIR for
applications, GIMPS for general signaling Fair multicast resource allocation (P.
Mendes)
IP telephony: QoS IP telephony: QoS estimationestimation
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-
to-end assessment
CINEMACINEMA Web interface
Administration User
configuration Unified
Messaging Notify by email rtsp or http
Portal Mode 3rd party IpTelSP
CINEMA componentsCINEMA components
RTSP
sipum
Cisco 7960
sipvxmlSIP
rtspdsipconfLDAP server
MySQL
PhoneJack interface
sipc
T1T1
sipd
mediaserver
RTSP
SIP-H.323converter
messagingserver
unified
server(MCU)
user database
conferencing
sip-h323
VoiceXMLserver
proxy/redirect server
Cisco2600
Pingtel
wireless802.11b
PBX
MeridianNortel
plug'n'sip
CINEMACINEMA Goal: fully integrated
communications platform: synchronous + asynchronous
collaboration calendaring multimedia collaboration: G.711 and
high-quality audio, video, shared whiteboard, chat, shared applications
Web control or VoiceXML interaction support pure VoIP and hybrids
Internet telephony: sipcInternet 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 interworkingPSTN interworkingNortel PBXPSTN
External T1/CAS
Regular phone(internal)
Call 93971341
SIP server
sipd
Ethernet
3
SQLdatabase
4 7134 => bob
sipc
5
Bob’s phone
GatewayInternal T1/CAS(Ext:7130-7139)
Call 71342
5551212
Internet telephony: Internet telephony: emergency emergency communicationscommunications
911 services architecture
emergency notification
EPAD
REGISTER sip:sos
Location: 07605
302 MovedContact: sip:[email protected]: tel:+1-201-911-1234
SIP proxyINVITE sip:sos
Location: 07605
Languages for service Languages for service creationcreation
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: APIsInternet telephony: APIs
APIs for IM and presence (JAIN JSR) design and implementation cooperation with Panasonic
Call Processing LanguageCall Processing Language
XML-based language<incoming>
<address-switch field="origin" subfield="host">
<address subdomain-of="example.com">
<location url="sip:[email protected]">
<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: Mobile ad-hoc networks: 7DS7DS
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)
7DS7DS
Content-independent: works for any web object
Uses standard caching mechanism After 25’, 90% of interested users
have data (25 hosts/ ) Also, data upload:
2km
7DS research issues7DS 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
Dotslash – A WebDotslash – A WebHotspot Rescue SystemHotspot Rescue System
Web Hotspot A sudden, dramatic surge of request
rate Short-term overload: long delay or no
service Challenges
Hard to predict Build up quickly Large magnitude
DotslashDotslash Motivation
One site can dramatically vary in request rate insufficient capacity
A group of sites peak at different time, spared capacity at some sites
Rescue service Dynamic collaboration among
different sites Enable a site to expand its capacity
dynamically and quickly
Functional ComponentsFunctional Components
Workload monitoring Discovery of spare capacity at
other sites Request distribution and
redirection Dynamic virtual hosting Dynamic replication of content Rescue relationship management
Fairness for multicastFairness for multicast
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.
Differentiated Service (DiffServ) networks Differentiated Service (DiffServ) networks divide traffic into different service quality divide traffic into different service quality levels, considering their quality levels, considering their quality requirements:requirements:
Multi-receiver fair Multi-receiver fair allocationallocation
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.
Provide fair distribution of Provide fair distribution of AssuredAssured services resources between multimedia services resources between multimedia multicast flows considering:multicast flows considering:
Quality of service: pricingQuality of service: pricing
Bandwidth: decrease of marginal returns adaptive services
Bandwidth
CostU1 U2
U3 Budget
Bandwidth pricingBandwidth 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 locationService location
Enhancements to Service Location Protocol (SLP): reliability and scaling (meshed SLP) remote discovery attributes