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The SAHARA Project: Composition and Cooperation in the New Internet


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Title: The SAHARA Project: Composition and Cooperation in the New Internet

The SAHARA ProjectComposition and
Cooperationin the New Internet
  • Randy H. Katz, Anthony Joseph, Ion Stoica
  • Computer Science Division
  • Electrical Engineering and Computer Science
  • University of California, Berkeley
  • Berkeley, CA 94720-1776

Presentation Outline
  • Service Architecture Opportunity
  • SAHARA Project Motivation
  • SAHARA Reference Architecture
  • Mechanisms for Service Composition
  • Summary and Conclusions

Presentation Outline
  • 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,
  • 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
  • No single technical architecture likely to
    dominate think overlays, system of systems

Distributed Service Architectures for Converged
  • Converged Networks
  • Public Switched Telephone Network (PSTN)
  • Internet/Public Switched Data Network (PSDN)
  • Mobile Internet
  • Converged Structure?
  • Distributed Service Architecture
  • Services
  • -Ility connectivity
  • Rich call new call features
  • Infrastructure services proxies, search,
  • Enablers for distributed apps event content

Services in Converged Networks
Services in Converged Networks
New Kind of Communications-Oriented Service
  • Emerging, still developing, in a highly
    heterogeneous environment
  • Rapid development/deployment of new services
  • 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
  • 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
  • Service Architecture Opportunity
  • SAHARA Project Motivation
  • SAHARA Reference Architecture
  • Mechanisms for Service Composition
  • Summary and Conclusions

Scenario ServiceComposition
The Sahara Project
  • 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, access-control models
  • Functional elements
  • Service discovery
  • Service-level agreements
  • Service composition under constraints
  • Redirection to a service instance
  • Performance measurement infrastructure
  • Constraints based on performance, access control,
  • Service modeling and verification

Problems and SolutionsThe 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
  • Overlays, cooperation

Internet Connectivity and Processing
Interconnected WorldAgile 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
  • 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

Internet Service Composition
Competition vs. Cooperation
  • Internet Service Providers Competition
  • Peering for packet transport BGP protocol
  • Charging based on traffic volumes

Hot Potato Routing
Composition and CooperationMobile Virtual
Network Operator
  • MVNO has everything but its own physical network

Mobile Virtual Network OperatorComposition and
GPRS Transit Peering, Cooperation, Composition
Per Johannson, Ericsson Research
PeeringPolicy-Based Routing
  • Multi-homing
  • Reliability of network connectivity
  • Traffic discrimination

Primary Transit Network
End Network
Berkeley Campus
Dorm Traffic
Alternative Transit Network
Research Traffic
Peer Network
Peer Network
Peer Network
Peer Networks
OverlaysCreating New Interdomain Services
  • Deploy new services above the routing layer
  • E.g., interdomain multicast management and
  • E.g., alternative connectivity for performance,

Isolated Intra-cloud service
Traditional unicast peering
Steve McCanne
OverlaysBrokered Resources for Applications
  • Examples
  • Multicast management and peering at application
  • Implement performance qualities at overlay level

Steve McCanne
CompositionWireless ISPs (wISPs)
  • T-Mobile Wireless Broadband (MobileStar), WayPort
  • Traditional network ISP, subscription-based
    services in public places
  • Hotels (Wayport), airports (Wayport _at_ SJ
    airport), airport clubs (T-Mobile _at_ AA Admirals
    Club), and cafes (T-Mobile _at_ 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
  • Ipass, GRIC
  • Secure remote access for mobile employees
  • Simplify connection establishment and login,
    wireless VPN support

Composition of Wireless Infrastructure Services
Billing, ECommerce Authentication Inter-site
Full Service Network Operator
Premises-based Access
Presentation Outline
  • 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,
  • 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
  • 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
  • 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
  • Brokered
  • Single provider, the Broker, uses functionalities
    provided by underlying service providers,
    encapsulates these to compose an end-to-end
  • Examples
  • Cooperative roaming among separate mobile
  • Brokered JAL restaurant guide

Service Composition Models
Layered Reference Model for Service Composition
End-User Applications
Applications Services
Application Plane
Middleware Services
End-to-End Network With Desirable Properties
Enhanced Paths
Connectivity Plane
Enhanced Links
IP Network
Layered Reference Modelfor Service Composition
Composed Service at Layer i
Layered Reference Modelfor 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
  • 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
  • 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
  • Authorization control scheme w/ credential
    transformations to enable cross-domain service
  • Federated admin domains with credential
    transformation rules based on established peering
  • 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

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
  • 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
  • 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
  • Status architectural specification driven by
    selected applications and underlying wide-area
  • 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.

Recent Publications
  • 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
  • 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
    (ICICS2001), Xian, China, (November 2001).

Recent Publications
  • J. Shih, R. H. Katz, Pricing Experiments for a
    Computer-Telephony-Service Usage Allocation,
    IEEE Globecom 2001, San Antonio, TX, (November
  • Y. Chen, R. H. Katz, J. Kubiatowicz, Replica
    Placement for Scalable Content Delivery,
    Proceedings First International Conference on
    Peer-to-Peer Systems (IPTPS02), 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
  • 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

Recent Publications
  • Y. Chawathe, M. Seshadri, Broadcast Federation
    An Application-layer Broadcast Internet,
    Proceedings Network and Operating System Support
    for Digital Audio and Video (NOSSDAV02), Miami
    Beach, FL, (May 2002).
  • L. Subramanian, V. Padmanabhan, R. H. Katz,
    Geographic Properties of Internet Routing,
    USENIX Conference, Monterey, California, (June
  • 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
  • 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
  • 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

SAHARA A Revolutionary Service Architecture for
Future Telecommunications Systems
  • Randy H. Katz, Anthony Joseph, Ion Stoica
  • Computer Science Division
  • Electrical Engineering and Computer Science
  • University of California, Berkeley
  • Berkeley, CA 94720-1776

Work in Progress
  • 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

Congestion Pricing at Access Links
  • 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
  • Effective
  • If entice half of users to choose lower QoS
    during congestion, then reduce burstiness at
    access links by 25

Auction-based Resource Allocation
  • Problem
  • Efficiently and effectively allocate resources
    according to applications dynamic requirements
  • Approach
  • Leveraging auction schemes and work-load
  • 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 can dynamically change applications
    priority by changing the token allocation rate.
  • Status
  • On-going work
  • First application bandwidth allocation in ad hoc
    wireless networks

Bandwidth Allocation
R1 attaches new certificate to the refresh message
  • 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

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 dampingRFC2439
  • Unexpectedflap damping delays convergence!
  • Topology clique of routers
  • Solution selective flap damping sigcomm02
  • Duplicate suppression
  • Ignore flaps caused by transient convergence
  • 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
  • Identified current routing behavior
  • Inferred AS relationships, topology
  • Next gather traffic data, finish code, emulate

Backup Path Allocation in Overlay Networks
  • Challenge
  • 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
  • Problem
  • Find a primary and backup path pair with minimal
    failure probability based on correlated overlay
    link failures
  • Approach
  • Decouple backup path routing from primary path
  • Route backup paths based on failure probability
    cost which measures the incremental path failure
    probability caused by using a link in the path
  • Status
  • Finished work, submitted to ICNP02

Host Mobility Using an Internet Indirection
  • The Problem
  • Internet hosts increasingly mobileneed to
    remain reachable
  • Flows should not be interrupted
  • IP address represents unique host ID net
  • ROAM (Robust Overlay Architecture for Mobility)
  • Leverages i3 overlay network triggers forward
  • Efficiency, robustness, location privacy,
    simultaneous mobility
  • No changes to end-host kernel or applications
  • Cost i3 infrastructure, and proxies on
  • Simulation Experimental Results
  • Stretch lower than MIP-bi ? able to choose nearby
  • 50-66 of MIP-tri when 5-28 domains deploy i3
  • Even 4 handoffs in 10 seconds have little impact
    on TCP performance

(ID, data)
(ID, R)
Sender (S)
(ID, data)
(ID, R)
Receiver (R)
Multicast Broadcast Federation
  • Goal compose different non-interoperable
    multicast domains to provide an end-to-end
    multicast service.
  • Should work for both IP and App-layer protocols.
  • Approach overlay of Broadcast Gateways (BGs)
  • BGs establish peering between domains.
  • Inside a domain, local multicast capability is
  • Clustered gateways for scalability.
  • Independent data flows and control flow.

Broadcast Domains
IP Mul
  • Implementation
  • 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
  • Good scalability
  • Good accuracy stability
  • Tested with NLANR
  • AMP Keynote data
  • Small overhead
  • Incrementally deployable
  • CMG journal 02

Cluster C
Cluster B
Cluster A
Distance from monitor to its hosts
Distance measurements among monitors
End Host
Availability in Wide-AreaService Composition
Text to audio
  • Issue Multi-provider ? WA composition
  • Poor availability of Internet path ? Poor service
    availability for client

Text to audio
  • gt15sec outage
  • Note BGP recovery could take several minutes
  • 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
  • See SPECTS02 paper
  • More recent results on load balancing across
    service replicas
  • End-to-end recovery in about 3.6sec 2sec
    detection, 600ms signaling, 1sec state

WA setup UCB, Berk. (Cable), SF (DSL), Stan.,
CMU, UCSD, UNSW (Aus), TU-Berlin (Germany)
Authorization Control Across Administrative
Trusted third party
Domain 1
Should grant access?
Authorization Authority
Request - certificates - credentials
Policy compliance check
Certificates Credentials
Credential transformation
Domain 2
Trust peering agreement - credential
transformation rule
  • Authorization authority
  • Provides authorization decision service.
  • Manages different verification methods and
  • Trust peering agreement
  • Credential transformation rule
  • Acceptable verification method

Work in Progress
  • Applications Services
  • Voice Over IP
  • Adaptive Content Distribution
  • (Universal In-Box)

IP Telephony Gateway Selection
  • Results
  • Congestion sensitive pricing decreases
    unnecessary call blocking, increases revenue, and
    improves economic efficiency
  • Hybrid redirection achieves good QoS and low
    blocking probability
  • Goal High quality, economically efficient
    telephony over the Internet
  • Questions How to
  • Perform call admission control?
  • Route calls thru converged net?

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

data plane
data source
  • Close to optimal of replicas wrt latency
  • Small latency bandwidth for sending updates
  • IPTPS 02
  • Pervasive 02

Web server
SCAN server
network plane
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