The SAHARA Project: Composition and Cooperation in the New Internet

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

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, 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
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, commerce Enablers for distributed apps: event & content distribution

Services in Converged Networks

New Kind of Communications-Oriented 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

Scenario: Service Composition
User NTTDoCoMo Restaurant Guide Service Tokyo JAL Babblefish Translator Zagat Guide UI Sprint User Salt Lake City

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, 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
Access Networks Cable Modem LAN Premises- based WLAN Operator- Core Networks Transit Net Private Peering NAP Public Peering H.323 Data RAS Analog DSLAM Internet Datacenter PSTN Regional Wireline Voice Cell

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 Application-specific Overlay Networks (Multicast Tunnels, Mgmt Svrcs) Global Packet Network Internetworking (Connectivity) ISP CLEC

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

Composition and Cooperation: Mobile Virtual Network Operator
MVNO has everything but its own physical network

Mobile Virtual Network Operator: Composition and Cooperation
InterCall M-to-N Relationships Competition one2one 1-to-1 Relationship

GPRS Transit: Peering, Cooperation, Composition
Operator B SGSN DNS BG Operator A GGSN Operator C SGSN DNS BG GRX R DNS GPRS Peering Network .gprs R GPRS Peering Network GRX DNS R Per Johannson, Ericsson Research

Peering Policy-Based Routing
Multi-homing Reliability of network connectivity Traffic discrimination Primary Transit Network New Primary Transit End Network Berkeley Campus Dorm Traffic Alternative Transit Network Research Traffic Fail-over Peer Network Peer Network CalREN Peer Network Peer Networks

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 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 SJ airport), airport clubs AA Admirals Club), and cafes 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 Private Brand Net Operator (MVNO) WISP Aggregator Single Sign-on Unified Billing SLN Aggregator Billing, ECommerce Authentication Inter-site Mobility Revenue Sharing Single Location Network Operator (SLN) Cooperative Networking Full Service Network Operator Full Service Network Operator Single Location Network Operator (SLN) Premises-based Access

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 Service Negotiation & control path Service Service Data flow Brokered Negotiation & control path Broker Service Data flow

Layered Reference Model for Service Composition
End-User Applications Composition Service Applications Services Application Plane Middleware Services End-to-End Network With Desirable Properties Enhanced Paths Connectivity Plane Enhanced Links IP Network

Composed Service at Layer i Policy Management Dynamic Resource Allocation Interoperabilty Measurement-based Adaptation Trust Management/ Verification Underlying Composition Techniques Services at Layer i-1 Other Services at Layer i Component Services

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

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

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

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

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

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

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 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 J. Shih, R. H. Katz, “Pricing Experiments for a Computer-Telephony-Service 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 Y. Chawathe, M. Seshadri, “Broadcast Federation: An Application-layer 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 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 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

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 Allocation

Congestion Pricing at Access Links
Internet Local Area Network Computer Access Router QoS $ 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
Problem Efficiently and effectively allocate resources according to application’s dynamic requirements Approach Leveraging auction schemes and work-load predictions Resource Auctioneer Bidder Application 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 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 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 8898 AS’s 971 AS’s 897 AS’s 129 AS’s 20 AS’s 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
The Overlay Network The Underlying Network 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 routing 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 ICNP’02 Randy, please note the animations in the figure. It shows the process of setting up the primary and backup path in the overlay network. I also want to use it to show link sharing in the underlying network.

Host Mobility Using an Internet Indirection Infrastructure
The Problem Internet hosts increasingly mobile; need to remain reachable Flows should not be interrupted IP address represents unique host ID & net location ROAM (Robust Overlay Architecture for Mobility) 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 (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 used. Clustered gateways for scalability. Independent data flows and control flow. Source Broadcast Domains CDN IP Mul SSM Clients BG Data Peering 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 performance Good scalability Good accuracy & stability Tested with NLANR AMP & Keynote data Small overhead Incrementally deployable [SIGMETRICS PAPA 02] & [CMG journal 02] Cluster C Cluster B Cluster A Monitor Distance from monitor to its hosts End Host Distance measurements among monitors

Availability in Wide-Area Service Composition
Text Source Text to audio Issue: Multi-provider  WA composition Poor availability of Internet path  Poor service availability for client Text Source Text to audio >15sec outage Note: BGP recovery could take several minutes [Labovitz’00] 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… End-to-end recovery in about 3.6sec: 2sec detection, ~600ms signaling, ~1sec state restoration Composition across providers implies path could stretch across the wide-area For instance, the picture shows a service involving a text-source such as , and a text-to-speech engine Wide-area Internet path availability is not great (studies by Labovitz, et.al.) This means poor availability for the composed service Make use of service replicas to dynamically switch from one service instance to another We have shown two things: Quick failure detection makes sense (within about 2sec), using aggressive heart-beats Scalable messaging – when 1000s of client sessions have to restored simultaneously, system does not break down due to message flood More details in SPECTS’02 paper The graph shows an experiment we ran across the wide-area, across 8 hosts These hosts represent university hosts in US, commercial end-points, as well as trans-continental links There are two client sessions of the composed text-to-speech application: one with recovery mechanism enabled, one without X-axis shows time, as the sessions proceed Y-axis shows the loss-percentage of audio packets received at the end-client, computed over 5sec intervals The session without any recovery mechanism sees an outage of over 15sec Due to recovery, the green line recovers in about 3.6sec (within bounds of end-client buffering) We have also studied algorithms for load-balancing across service replicas, in this context of dynamic session recovery to improve availability WA setup: UCB, Berk. (Cable), SF (DSL), Stan., CMU, UCSD, UNSW (Aus), TU-Berlin (Germany)

Authorization Control Across Administrative Domains
Trusted third party Should grant access? Authorization Authority Service Decision Request - certificates - credentials Policy compliance check Verification Certificates Credentials Credential transformation Domain 2 User Trust peering agreement - credential transformation rule Authorization authority Provides authorization decision service. Manages different verification methods and credentials. 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
ITG LS ITG LS Our system architecture is based on that specified in the Telephony Routing over IP framework. There are three types of functional entities: First, Internet Telephony Gateways, or ITGs, act as application layer proxies to provide call transit to the PSTN. These ITGs may be widely distributed Geographically and may offer varying degrees of reachability to various locations on the Internet. Second, End hosts running IP Telephony software perform encoding and signaling for the call. Finally, Location Servers maintain a distributed database of ITG resources in the network. When an ITG advertises a status update to its LS (click) The LS propagates the advertisement to neighboring Administrative domains (click) which propagate the advertisement to their peers until all LSs receive the update. Note that: The IP network interconnecting location servers suffers from packet loss and delay. Because of this, the location server can have out of date information. These entities are grouped into administrative domains, which are operated by a single provider. Call setup takes place as follows: (click) Software running on the user’s pc contacts the LS (click) The LS returns an ITG’s IP address (click) The user sends a connection setup request (click) A call accept or reject is then returned to the client. (click) If the call is accepted, the call is path is setup over the PSTN, (click) and the connection is then established. ITG LS Gateway (ITG) IP Terminal Location Server (LS) ITG LS Load Advertisement Call Session 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 source data plane Close to optimal # of replicas wrt latency guarantee Small latency & bandwidth for sending updates [IPTPS 02] & [Pervasive 02] cache adaptive coherence always update replica Tapestry mesh client Web server SCAN server network plane

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