Transcript No Slide Title - Department of Computer Science and Engineering

The SAHARA Project:
Composition and Cooperation
in the New Internet
Randy H. Katz, Anthony Joseph, Ion Stoica
Computer Science Division
Electrical Engineering and Computer Science Department
University of California, Berkeley
Berkeley, CA 94720-1776
Presentation Outline
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Presentation Outline
•
•
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Traditional View of Networking
• All about protocols and the OSI layers
– Protocol details: link-state vs. distance vector,
TCP
– Protocol layering
– Multiaccess technology
– Switching and routing
– Naming
– Error control
– Flow control & scheduling
– Special topics like multicast and mobility
The New Opportunity
• New things you can do inside the network
• Connecting end-points to “services” with processing
embedded in the network fabric
• Not protocols but “agents,” executing in places in
the network
• Location-aware, data format aware
• Controlled violation of layering necessary!
• Distributed architecture aware of network topology
• No single technical architecture likely to dominate:
think overlays, system of systems
Distributed Service Architectures
for Converged Networks
• Converged Networks
–
–
–
–
Public Switched Telephone Network (PSTN)
Internet/Public Switched Data Network (PSDN)
Mobile Internet
Converged Structure?
• Distributed Service Architecture
– Services
•
•
•
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“-Ility” connectivity
Rich call: new call “features”
Infrastructure services: proxies, search, commerce
Enablers for distributed apps: event & content distribution
Services in Converged Networks
Services in Converged Networks
New Kind of CommunicationsOriented Service Architecture
• Emerging, still developing, in a highly heterogeneous
environment
– Rapid development/deployment of new services & apps
– Delivered to radically different end devices (phone, computer,
info appliance) over diverse access networks (PSTN, LAN,
Wireless, Cellular, DSL, Cable, Satellite)
– Exploiting Internet-based technology core: clients/server,
applications level routers, TCP/IP protocols, Web/XML
formats
– Beyond traditional “call processing” model: client-proxy-server
plus application-level partitioning
– Built upon a new business model being driven by the evolution
of the Internet: traditional “managed” networks and services
versus emerging “overlay” networks and services structured on
top of and outside of the above
– Composition via cooperation or brokering to achieve enhanced
performance and reliability
Presentation Outline
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•
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Scenario: Service
Composition
Restaurant
Guide Service
JAL
UI
Babblefish
Translator
NTTDoCoMo
Zagat Guide
User
Tokyo
Sprint
Salt Lake
City
User
The “Sahara” Project
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•
•
•
•
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Service
Architecture for
Heterogeneous
Access,
Resources, and
Applications
Sahara Research Focus
• New mechanisms, techniques for end-to-end services
w/ desirable, predictable, enforceable properties
spanning potentially distrusting service providers
– Tech architecture for service composition & inter-operation
across separate admin domains, supporting peering &
brokering, and diverse business, value-exchange, accesscontrol models
– Functional elements
•
•
•
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Service discovery
Service-level agreements
Service composition under constraints
Redirection to a service instance
Performance measurement infrastructure
Constraints based on performance, access control,
accounting/billing/settlements
• Service modeling and verification
Problems and Solutions
“The Network Effect”
• Creating and deploying new services
– Development and deployment expense
• Cost of 3G licenses and networks
• “Even if I had $1 billion and set up 1000s of locations, I
could never in my network have a completely ubiquitous
footprint.”—Sky Dayton, founder of Boingo
• Composition, cooperation, overlays
• Achieving desirable end-to-end properties
– Control of the end-to-end path
– Cooperation, peering, overlays (brokering)
• Evolving network services
– Difficult to change global operational infrastructure
– Overlays, cooperation
Internet Connectivity and Processing
Cable
Modem
Premisesbased
Access
Networks
Core Networks
WLAN
Transit Net
WLAN
Operatorbased
Cell
Cell
Cell
Regional
LAN
Transit Net
Premisesbased
WLAN
LAN
Internet
Datacenter
NAP
Public
Peering
Data
Voice
Analog
Transit Net
H.323
RAS
H.323
PSTN
LAN
Private
Peering
DSLAM
Data
Voice
Wireline
Regional
Interconnected World:
Agile or Fragile?
• Baltimore Tunnel Fire, 18 July 2001
– “… The fire also damaged fiber optic cables, slowing Internet service
across the country, …”
– “… Keynote Systems … says the July 19 Internet slowdown was not
caused by the spreading of Code Red. Rather, a train wreck in a
Baltimore tunnel that knocked out a major UUNet cable caused it.”
– “PSINet, Verizon, WorldCom and AboveNet were some of the bigger
communications companies reporting service problems related to
‘peering,’ methods used by Internet service providers to hand traffic
off to others in the Web's infrastructure. Traffic slowdowns were
also seen in Seattle, Los Angeles and Atlanta, possibly resulting from
re-routing around the affected backbones.”
– “The fire severed two OC-192 links between Vienna, VA and New
York, NY as well as an OC-48 link from, D.C. to Chicago. … Metromedia
routed traffic around the fiber break, relying heavily on switching
centers in Chicago, Dallas, and D.C.”
Internet Service Composition
Applications
(Portals, E-Commerce,
E-Tainment, Media)
Appl Infrastructure Services
(Distribution, Caching,
Searching, Hosting)
AIP
ISV
Application-specific Servers
(Streaming Media, Transformation)
ASP
Internet
Data Centers
ISP
CLEC
Application-specific
Overlay Networks
(Multicast Tunnels, Mgmt Svrcs)
Global Packet Network
Internetworking
(Connectivity)
Competition vs. Cooperation
• Internet Service Providers: Competition
– Peering for packet transport: BGP protocol
– Charging based on traffic volumes
ISP A
Peering
Point
Hot Potato
Routing
ISP B
Peering
Point
Composition and Cooperation:
Mobile Virtual Network Operator
MVNO has everything but its own physical network
Mobile Virtual Network Operator:
Composition and Cooperation
InterCall
one2one
Competition
one2one
1-to-1 Relationship
M-to-N Relationships
GPRS Transit: Peering,
Cooperation, Composition
Operator A
DNS
BG
Operator C
BG
GGSN
GPRSPeering
PeeringNetwork
Network
GPRS
R
R
GRXR
R
R
DNS
R
Operator B
DNS
SGSN
DNSDNS
R
.gprs
BG
R
R
GRX
GRX
DNS
R
GRX
DNS
R
DNS
SGSN
R
Operator C
BG
DNS
SGSN
Per Johannson, Ericsson Research
Peering
Policy-Based Routing
• Multi-homing
– Reliability of network connectivity
– Traffic discrimination
Primary
Transit
Network
Berkeley
Dorm
Campus
End Network
Traffic
Alternative
New Primary
Transit
Research
Transit
Fail-over
Network
Traffic
Peer
Peer
CalREN
Peer
Network
Network
Networks
Network
Overlays
Creating New Interdomain Services
• Deploy new services above the routing layer
– E.g., interdomain multicast management and peering
– E.g., alternative connectivity for performance,
resilience
Isolated
Intra-cloud
service
Administrative
domain
Admin
domain
Admin
domain
Administrative
domain
Admin
domain
Traditional
unicast
peering
Steve McCanne
Overlays
Brokered Resources for Applications
• Examples:
– Multicast management and peering at application level
– Implement performance qualities at overlay level
Steve McCanne
Composition:
Wireless ISPs (wISPs)
• T-Mobile Wireless Broadband (MobileStar), WayPort
– Traditional network ISP, subscription-based services in public places
– Hotels (Wayport), airports (Wayport @ SJ airport), airport clubs (TMobile @ AA Admirals Club), and cafes (T-Mobile @ Starbucks)
– Diverse billing models: e.g., 24-hour subscription at a hotel
• Boingo, Joltage, hereUare, NetNearU
– “Aggregator” of access, e.g., Boingo aggregates Wayport, hereUare
– Client s/w including network sniffer/location finder, back-end
authentication/secure VPN/settlement services
– Revenue sharing with micro ISPs/single local network (SLN)
– Diverse billing models: subscriptions as well as pay per use
• Sputnik
– Cooperative wireless neighbor-to-neighbor networks
• Ipass, GRIC
– Secure remote access for mobile employees
– Simplify connection establishment and login, wireless VPN support
Composition of Wireless
Infrastructure Services
VPN Operator, Client-Software
WISP Aggregator
Private Brand Net
Operator (MVNO)
Single Sign-on
Unified Billing
Billing, ECommerce
Authentication
Inter-site Mobility
SLN Aggregator
Single Location
Network Operator
Single Location(SLN)
Network Operator
Single Location
(SLN)
Network Operator Cooperative
(SLN)
Networking
Revenue
Sharing
Full Service
Network
Full Service
Operator
Network
Full Service
Premises-based
Operator
Network
Operator
Access
Presentation Outline
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Technical Challenges
• Trust management and behavior verification
– Meet promised functionality, performance, availability
• Adapting to network dynamics
– Actively respond to shifting server-side workloads and network
congestion, based on pervasive monitoring & measurement
– Awareness of network topology to drive service selection
• Adapting to user dynamics
– Resource allocation responsive to client-side workload variations
• Resource provisioning and management
– Service allocation and service placement
• Interoperability across multiple service providers
– Interworking across similar services deployed by different providers
Service Composition Models
• Cooperative
– Individual component service providers interact in
distributed fashion, with distributed responsibility, to
provide an end-to-end composed service
• Brokered
– Single provider, the Broker, uses functionalities provided
by underlying service providers, encapsulates these to
compose an end-to-end service
• Examples
– Cooperative: roaming among separate mobile networks
– Brokered: JAL restaurant guide
Service Composition Models
Cooperative
Negotiation & control path
Service
Service
Service
Data flow
Brokered
Negotiation & control path
Broker
Service
Data flow
Service
Service
Layered Reference Model for
Service Composition
Middleware Services
End-to-End Network
With Desirable Properties
Enhanced Paths
Enhanced Links
IP Network
Connectivity
Plane
Service
Composition
Applications Services
Application
Plane
End-User Applications
Layered Reference Model
for Service Composition
Composed Service at Layer i
Measurement-based
Adaptation
Interoperabilty
Dynamic Resource
Allocation
Policy
Management
Trust Management/
Verification
Underlying
Composition
Techniques
Services
at Layer i-1
Services
ServicesatatLayer
Layeri-1
i-1
Component Services
Services
at Layer
i-1
Other
Services
at Layer i
Layered Reference Model
for Service Composition
• Connectivity Plane
– End-to-end network with desirable properties composed
on top of commodity IP network
– Enhanced Links & Paths: QoS and protocol verification
within and between connectivity service providers
• Applications Plane
– Services strategically placed and actively managed within
the network topology
– Applications and Middleware Services: end-client
oriented vs. infrastructure oriented
Presentation Outline
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Mechanisms for Service
Composition
• Measurement-based Adaptation
– Examples
• General-purpose third party end-to-end Internet host
distance monitoring and estimation service
• Universal In-box: Application-specific middleware
measurement layer to exchange network and server
load using link-state algorithm
• Content Distribution Networks: measurement-based
DNS-based server selection to redirect client to
closest service instance
Mechanisms for Service
Composition
• Utility-based Resource Allocation Mechanisms
– Examples
• Auctions to dynamically allocate resources; applied for
spectrum/bandwidth resource assignments to MVNO
from underlying competiting MNOs
• Congestion pricing: influence user behavior to better
utilize scarce resources; applied in:
– Voice port allocation to user-initiated calls in H.323
gateway/Voice over IP service management
– Wireless LAN bandwidth allocation and management
– H.323 gateway selection, redirection, and load balancing for
Voice over IP services
Mechanisms for Service
Composition
• Trust Mgmt/Verification of Service & Usage
– Authentication, Authorization, Accounting Services
• Authorization control scheme w/ credential
transformations to enable cross-domain service invocation
• Federated admin domains with credential transformation
rules based on established peering agreements
• AAA server makes authorization decisions, liberating
providers from preparing rules for each affiliated domain
– Service Level Agreement Verification
• Verification and usage monitoring to ensure properties
specified in SLA are being honored
• Border routers monitoring control traffic from different
providers to detect malicious route advertisements
Mechanisms for Service
Composition
• Policy Management
– Visibility into local policies to better coordinate
global policies among (cooperating) service
providers
– Developing inter-AS architecture for load
balancing, performance and failure mode
policies to be applied throughout the network
• Internet topology discovery through AS relationship
map of the Internet plus measurement infrastructure
• Policy agent framework for inter-AS negotiation to
manage incoming traffic
Mechanisms for Service
Composition
• Interoperability through Transformation
– Interoperability of data, protocols, policies
among composed service providers
– Example
• Broadcast federation: global multicast service
composed from multicast implementations in
different provider domains
• Protocol transformation gateways between admin
domains employing non-interoperable multicast
protocol implementations
Presentation Outline
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Service Architecture Opportunity
SAHARA Project Motivation
SAHARA Reference Architecture
Mechanisms for Service Composition
Summary and Conclusions
Summary and Conclusions
• Goal: Evolve (mobile) Internet architecture to better
support multi-network/multi-service provider model
– Dynamic environment, location-based implies larger numbers
of service providers & service instances
• Status: architectural specification driven by selected
applications and underlying wide-area services
• Focus:
– Composition across confederated vs. independent service
providers: peer-to-peer vs. brokering
– Explore new techniques/technologies:
• Market-based mechanisms
• Trust management, SLA verification, perf. monitoring
Recent Publications
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C. Chuah, L. Subramanian, A. D. Joseph, R. H. Katz, “QoS
Provisioning Using A Clearing House Architecture,” 8th
International Workshop on Quality of Service (IWQOS 2000),
Pittsburgh, PA, (June 2000).
S. Zhuang, B. Zhao, A. Joseph, R. H. Katz, J. Kubiatowicz, “Bayeux:
An Architecture for Wide-Area, Fault-Tolerant Data Dissemination
Protocol,” ACM NOSSDAV 2001, New York, (June 2001).
Z. Mao, W. So, R. H. Katz, “Network Support for Mobile Multimedia
Using a Self-Adaptive Distributed Proxy,” ACM NOSSDAV 2001,
New York, (June 2001).
Y. Chen, A. Bargteil, R. H. Katz, “Quantifying Network Denial of
Service: A Location Service Case Study,” Third International
Conference on Information and Communication Security
(ICICS’2001), Xi’an, China, (November 2001).
Recent Publications
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J. Shih, R. H. Katz, “Pricing Experiments for a Computer-TelephonyService Usage Allocation,” IEEE Globecom 2001, San Antonio, TX,
(November 2001).
Y. Chen, R. H. Katz, J. Kubiatowicz, “Replica Placement for Scalable
Content Delivery,” Proceedings First International Conference on
Peer-to-Peer Systems (IPTPS’02), Cambridge, MA, (March 2002).
T. Suzuki, R. H. Katz, “An Authorization Control Framework to Enable
Service Composition Across Domains,” Proceedings Eleventh World
Wide Web Conference (WWW2002), Honolulu, HI, (May 2002).
M. Caesar, D. Ghosal, R. H. Katz, “Resource Management for IP
Telephony Networks,” Proceedings 10th International Workshop on
Quality of Service (IWQoS), Miami Beach, FL, (May 2002).
S. Machiraju, M. Seshadri, I. Stoica, “A Scalable and Robust Solution
for Bandwidth Allocation,” Proceedings 10th International Workshop
on Quality of Service (IWQoS), Miami Beach, FL, (May 2002).
Recent Publications
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Y. Chawathe, M. Seshadri, “Broadcast Federation: An Applicationlayer Broadcast Internet,” Proceedings Network and Operating
System Support for Digital Audio and Video (NOSSDAV’02), Miami
Beach, FL, (May 2002).
L. Subramanian, V. Padmanabhan, R. H. Katz, “Geographic Properties
of Internet Routing,” USENIX Conference, Monterey, California,
(June 2002).
Z, Mao, C. Cranor, F. Douglis, M. Rabinovich, O. Spatscheck, J. Wang,
“A Precise and Efficient Evaluation of the Proximity between Web
Clients and their Local DNS Servers,” USENIX Conference,
Monterey, California, (June 2002).
L. Subramanian, S. Agarwal, J. Rexford, R. H. Katz, “Characterizing
the Internet Hierarchy from Multiple Vantage Points,” IEEE
Infocomm Conference, New York, NY, (June 2002).
Recent Publications
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J. Shih, R. H. Katz, “Evaluating Tradeoffs of Congestion Pricing for
Voice Calls,” Extended Abstract, ACM Sigmetrics Conference, San
Diego, California, (July 2002).
J. Shih, R. H. Katz, “Evaluating the Tradeoffs of Congestion Pricing
for Voice Calls,” 2002 International Symposium on Performance
Evaluation of Computer and Telecommunication Systems (SPECTS
2002), San Diego, California, (July 2002).
B. Raman, R. H. Katz, “Emulation-based Evaluation of an Architecture
for Wide-Area Service Composition,” 2002 International Symposium
on Performance Evaluation of Computer and Telecommunication
Systems (SPECTS 2002), San Diego, California, (July 2002).
Z. Mao, R. Govindan, S. Shenker, R. H. Katz, “Route Flap Damping
Exacerbates Internet Routing Convergence.” ACM SIGCOMM
Conference, Pittsburgh, PA, (August 2002).
Recent Publications
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B. Raman, S. Agrawal, Y. Chan, M. Caesar, W. Cui, P. Johannson, K. Lai,
T. Lavian, S, Machiraju, Z. Mao, G. Porter, T. Roscoe, M. Seshadri, J.
Shih, K. Sklower, L. Subramanian, T. Suzuki, S. Zhuang, A. D. Joseph,
R. H. Katz, I. Stoica, “The SAHARA Model for Service Composition
across Multiple Providers,” Pervasive Computing 2002, Zurich,
Switzerland, (August 2002).
Z. Mao, R. H. Katz, “A Framework for Universal Service Access using
Device Ensembles,” CRA Grace Murray Hopper Celebration of Women
in Computer Science Conference, Vancouver, BC, (October 2002).
SAHARA: A Revolutionary
Service Architecture for Future
Telecommunications Systems
Randy H. Katz, Anthony Joseph, Ion Stoica
Computer Science Division
Electrical Engineering and Computer Science Department
University of California, Berkeley
Berkeley, CA 94720-1776
Work in Progress
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•
•
•
Enhanced Links
Enhanced Paths
Middleware Services
Applications Services
Work in Progress
• Enhanced Links
– Congestion Pricing for Access Links
– Auction-based Resource (Bandwidth) Allocation
– Traffic Policing/Verification of Bandwidth
Allocation
Congestion Pricing at Access Links
Computer
Local Area Access Internet
Router
Network
QoS
Computer
$
• Setup
– 10 users
– 3 QoS (Slow-going, Moderate, & Responsive)
differ on degree of traffic smoothing
– 24 tokens/day, 15 minutes of usage per charge
• Acceptable
– Users make purchasing decision at most once every 15 minutes
• Feasible
– Changing prices cause users to select different QoS
• Effective
– If entice half of users to choose lower QoS during congestion,
then reduce burstiness at access links by 25%
Auction-based Resource Allocation
Application
Bidder
Auctioneer
Resource
• Problem
– Efficiently and effectively allocate
resources according to application’s
dynamic requirements
• Approach
– Leveraging auction schemes and
work-load predictions
• Features
– Bidders can place bids based on application requirements and
contention level.
– Bidders can place bids for near future resource requirements based
on recent history.
– Bidders can express both utility and priority to auctioneer.
– Auctioneer can dynamically change application’s priority by changing
the token allocation rate.
• Status
– On-going work
– First application: bandwidth allocation in ad hoc wireless networks
Bandwidth Allocation
• Problem: scalable (stateless)
and robust bandwidth
allocation
• Control Plane:
– Soft state
– Per-router per-period
certificates for robustness
without per-flow state
– Random sampling to prevent
duplicate refreshes
• Data Plane:
– Monitor aggregate flows
– Recursively split misbehaving
aggregates
R1 attaches new certificate
to the refresh message
misbehaving
aggregate – split it
Work in Progress
• Enhanced Paths
–
–
–
–
–
BGP Route Flap Dampening
BGP Policy Agents
Backup Path Allocation in Overlay Networks
Host Mobility
Multicast Interoperation
BGP: Stability vs. Convergence
• Problem:
– Stability achieved through flap damping[RFC2439]
– Unexpected:flap damping delays convergence!

Topology: clique
of routers

Solution: selective flap damping
[sigcomm02]
 Duplicate suppression:
Ignore flaps caused by transient
convergence instability
 Still contains stability


Eliminates undesired interaction!
Policy Management for BGP
• 3-15 minute failover time
• Slow response to congestion
• Unacceptable for Internet service
composition
•
•
•
Lack of distributed route control
Need distributed policy management
Explicit route policy negotiation
20 AS’s
129 AS’s
•
•
•
Identified current routing behavior
Inferred AS relationships, topology
Next : gather traffic data, finish code,
emulate
897 AS’s
971 AS’s
8898 AS’s
Backup Path Allocation in Overlay Networks
The Overlay Network
The Underlying Network
•
Challenge
•
Problem
•
Approach
•
Status
– Disjoint primary and backup path in the overlay network may share
underlying links because the overlay network cannot control underlying links
used by a path
– Find a primary and backup path pair with minimal failure probability based
on correlated overlay link failures
– Decouple backup path routing from primary path routing
– Route backup paths based on failure probability cost which measures the
incremental path failure probability caused by using a link in the path
– Finished work, submitted to ICNP’02
Host Mobility Using an Internet
Indirection Infrastructure
• The Problem
(ID, data)
(ID, R)
– Internet hosts increasingly mobile;
Sender (S)
need to remain reachable
(ID, data)
– Flows should not be interrupted
– IP address represents unique host ID & net location
• ROAM (Robust Overlay Architecture for Mobility)
–
–
–
–
(ID, R)
Receiver (R)
Leverages i3: overlay network triggers & forward packets
Efficiency, robustness, location privacy, simultaneous mobility
No changes to end-host kernel or applications
Cost: i3 infrastructure, and proxies on end-hosts
• Simulation & Experimental Results
– Stretch lower than MIP-bi  able to choose nearby triggers
– 50-66% of MIP-tri when 5-28% domains deploy i3 servers
– Even 4 handoffs in 10 seconds have little impact on TCP
performance
Multicast Broadcast Federation
•
Goal : compose different non-
interoperable multicast domains
to provide an end-to-end multicast
Broadcast
Domains
service.
SSM
Approach : overlay of Broadcast
Gateways (BGs)
– BGs establish peering
between domains.
– Inside a domain, local
multicast capability is used.
– Clustered gateways for
scalability.
– Independent data flows and
control flow.
CDN
IP Mul
– Should work for both IP and
App-layer protocols.
•
Source
Clients
BG
Data
•
Implementation :
Peering
– Linux/C++ event-driven program
– Easily customizable interface to
local multicast capability (~700
lines)
– Upto 1 Gbps BG thruput with 6
nodes.
– Upto 2500 sessions with 6
nodes.
Work in Progress
• Middleware Services
– Measurement and Monitoring Infrastructure
– Robust Service Composition
– Authorization Interworking
Internet Distance Monitoring Infrastructure
• Problem: N end hosts in different administrative domains, how to select
a subset to be probes, and build an overlay distance monitoring service
without knowing the underlying topology?
• Solution: Internet Iso-bar
– Clustering of hosts perceiving similar
performance
Cluster C
• Good scalability
• Good accuracy & stability
– Tested with NLANR
AMP & Keynote data
Cluster B
Cluster A
• Small overhead
• Incrementally deployable
• [SIGMETRICS PAPA 02]
& [CMG journal 02]
Monitor
Distance from monitor to its hosts
End Host
Distance measurements among monitors
Text
to
audio
Text
to
audio
Text Source
Availability in Wide-Area
Service Composition
• Issue: Multi-provider  WA composition
• Poor availability of Internet path  Poor
service availability for client
Text Source
• Fix: detect and recover from
failures using service replicas
• Highlight of results:
– Quick detection (~2sec) possible
– Scalable messaging for recovery
(can handle simultaneous failure
recovery of 1000s of clients)
– See SPECTS’02 paper
• More recent results on load
balancing across service
replicas…
• >15sec outage
• Note: BGP recovery could take
several minutes [Labovitz’00]
• End-to-end recovery in about
3.6sec: 2sec detection, ~600ms
signaling, ~1sec state restoration
WA setup: UCB, Berk. (Cable), SF (DSL), Stan.,
CMU, UCSD, UNSW (Aus), TU-Berlin (Germany)
Authorization Control Across
Administrative Domains
Domain 1
Trusted third party
Should grant access?
Service
Decision
Request
Policy compliance
check
- certificates
- credentials
Authorization
Authority
Verification
Credential
transformation
User
Domain 2
Trust peering agreement
- credential transformation rule
•
Authorization authority
•
Trust peering agreement
– Provides authorization decision service.
– Manages different verification methods and credentials.
– Credential transformation rule
– Acceptable verification method
Certificates
Credentials
Work in Progress
• Applications Services
– Voice Over IP
– Adaptive Content Distribution
– (Universal In-Box)
IP Telephony Gateway Selection
ITG
0.18
Random Redirection
Congestion and QoS Redirection
0.16
LS
ITG
LS
Blocking Probability
ITG
Call Blocking Probability
LS
0.14
0.12
0.1
0.08
0.06
0.04
0.02
ITG Gateway (ITG)
IP Terminal
LS Location Server (LS)
0
Call Session
Goal: High quality, economically
efficient telephony over the
Internet
 Questions: How to

Perform call admission control?
 Route calls thru converged net?

0
Load Advertisement

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Relative Weight of Congestion Sensitivity
1
Results:
Congestion sensitive pricing
decreases unnecessary call blocking,
increases revenue, and improves
economic efficiency
 Hybrid redirection achieves good
QoS and low blocking probability

SCAN: Scalable Content Access Network
• Problem: Provide content distribution to clients with small latency, small
# of replicas and efficient update dissemination
• Solution: SCAN
– Leverage P2P location services to improve scalability and locality
– Simultaneous dynamic replica placement & app-level multicast tree
construction
• Close to optimal #
of replicas wrt
latency guarantee
• Small latency &
bandwidth for
sending updates
• [IPTPS 02]
& [Pervasive 02]
data
source
data plane
replica
cache
always update
adaptive
coherence
Web
server
SCAN server
client
Tapestry mesh
network plane