The SAHARA Four-Layer Model; Case-studies in Composition

1. The SAHARA Four-Layer Model;Case-studies in Composition Bhaskaran Raman, Jimmy Shih, Randy H. Katz, SAHARA, EECS, U.C.Berkeley

2. Service Composition 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

3. Work in Progress • Enhanced Links • Congestion Pricing for Access Links • Auction-based Resource (Bandwidth) Allocation • Traffic Policing/Verification of Bandwidth Allocation

4. Computer Access Router Local Area Network Internet QoS Computer $ 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 QoS • Effective • If entice half of users to choose lower QoS during congestion, then reduce burstiness at access links by 25%

5. Application Bidder Auctioneer Resource Auction-based Resource Allocation • Problem • Efficiently and effectively allocate resources according to application’s dynamic requirements • Approach • Leveraging auction schemes and work-load predictions • Capabilities • 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

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

7. 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 Bandwidth Allocation R1 attaches new certificate to the refresh message misbehaving aggregate – split it

8. Work in Progress • Enhanced Paths • BGP Route Flap Dampening • BGP Policy Agents • Backup Path Allocation in Overlay Networks • Host Mobility • Multicast Interoperation

9. 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!

10. 20 AS’s 129 AS’s 897 AS’s 971 AS’s 8898 AS’s 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

11. The Overlay Network The Underlying Network 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 routing • Route backup paths based on failure probability cost which measures the incremental path failure probability caused by using a link in the path • Main Result • Can be 20-30% more robust compared to shortest disjoint path allocation • Status • Finished work, submitted to ICNP’02

12. Host Mobility Using an Internet Indirection Infrastructure (ID, data) (ID, R) • 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 Sender (S) (ID, data) (ID, R) Receiver (R)

13. 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. 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. Multicast Broadcast Federation Source Broadcast Domains CDN IP Mul SSM Clients BG Data Peering

14. Work in Progress • Middleware Services • Measurement and Monitoring Infrastructure • Robust Service Composition • Authorization Interworking

15. Internet Distance Monitoring Infrastructure • 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] • 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? Cluster C Cluster B Cluster A Monitor Distance from monitor to its hosts Distance measurements among monitors End Host

16. Text Source Text Source 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 • >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 WA setup: UCB, Berk. (Cable), SF (DSL), Stan., CMU, UCSD, UNSW (Aus), TU-Berlin (Germany)

17. Authorization Control Across Administrative Domains Domain 1 Trusted third party Should grant access? Authorization Authority Service • Authorization authority • Provides authorization decision service. • Manages different verification methods and credentials. • Trust peering agreement • Credential transformation rule • Acceptable verification method Decision Request - certificates - credentials Policy compliance check Verification Certificates Credentials Credential transformation Domain 2 User Trust peering agreement - credential transformation rule

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

19. Gateway (ITG) ITG Load Advertisement IP Terminal LS Location Server (LS) Call Session IP Telephony Gateway Selection LS ITG LS ITG LS ITG • 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?

20. replica cache always update adaptive coherence client Tapestry mesh 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] Web server SCAN server network plane

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

22. Idea: Use real implementation, emulate the wide-area network behavior (NistNET) • Opportunity: Millennium cluster Evaluation: Emulation Testbed Rule for 12 App Emulator Node 1 Rule for 13 Lib Rule for 34 Node 2 Rule for 43 Node 3 Node 4 Also have limited (8-node) wide-area testbed