Programmability: Network Virtualization
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Programmability: Network Virtualization






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    Programmability: Network Virtualization Programmability: Network Virtualization Presentation Transcript

    • Network Virtualization Jennifer Rexford Advanced Computer Networks Tuesdays/Thursdays 1:30pm-2:50pm
    • Introduction
      • Motivation for network virtualization
        • Deployment dilemma, too many design goals, and coordination constraint
      • Pluralist networks
        • Economic refactoring
        • Infrastructure and service providers
      • Research challenges
        • Systems challenges
        • Resource allocation
    • The Internet: A Remarkable Story
      • Tremendous success
        • From research experiment to global communications infrastructure
      • The brilliance of under-specifying
        • Best-effort packet delivery service
        • Key functionality at programmable end hosts
      • Enabled massive growth and innovation
        • Ease of adding hosts and link technologies
        • Ease of adding services (Web, P2P, VoIP, …)
      • But, change is easy only at the edge… 
    • Rethinking the Network Architecture
      • But, the Internet is showing signs of age
        • Security, mobility, availability, manageability, …
      • Challenges rooted in early design decisions
        • Weak notion of identity, tying address & location
        • Not just a matter of redesigning a single protocol
      • Revisit definition and placement of function
        • What are the types of nodes in the system?
        • What are their powers and limitations?
        • What information do they exchange?
    • Hurdle #1: Deployment Dilemma
      • An unfortunate catch-22
        • Must deploy an idea to demonstrate feasibility
        • Can’t get an undemonstrated idea deployed
      • A corollary: the testbed dilemma
        • Production network: real users, but can’t change
        • Research testbed: easy changes, but no users
      • Bad for the research community
        • Good ideas sit on the shelf
        • Promising ideas do not grow up into good ones
    • Hurdle #2: Too Many Design Goals
      • Many different system-engineering goals
        • Scalability, reliability, security, privacy, robustness, performance guarantees, …
        • Perhaps we cannot satisfy all of them at once
      • Applications have different priorities
        • Online banking: security
        • Web surfing: privacy, high throughput
        • Voice and gaming: low delay and loss
      • Compromise solution isn’t good for anyone
    • Hurdle #3: Coordination Constraint
      • Difficult to deploy end-to-end services
        • Benefits only when most networks deploy
        • No single network wants to deploy first
      • Many deployment failures
        • QoS, IP multicast, secure routing, IPv6,…
        • Despite solving real, pressing problems
      • Increasing commoditization of ISPs
      sender receiver 1 2 3
    • Virtualization to the Rescue
      • Multiple customized architectures in parallel
        • Multiple logical routers on a single platform
        • Isolation of resources, like CPU and bandwidth
        • Programmability for customizing each “slice”
    • Overcoming the Hurdles
      • Deployment Dilemma
        • Run multiple experimental networks in parallel
        • Some are mature, offering services to users
        • Isolated from others that are works in progress
      • Too Many Design Goals
        • Run multiple operational networks in parallel
        • Customized to certain applications and users
      • Coordination Constraint
        • Run multiple end-to-end services in parallel
        • Over equipment owned by different parties
    • Pluralist Future
    • The Case for Pluralism
      • Suppose we can break down the barriers…
        • Enable realistic evaluation of new ideas
        • Overcome the coordination constraint
      • Maybe there isn’t just one right answer
        • Maybe the problem is over-constrained
        • Too many goals, some of them conflicting
      • Maybe the goals change over time
        • And we’ll always be reinventing ourselves
        • The only constant is change
      • So, perhaps we should design for change
    • Different Services, Different Goals
      • Performance
        • Low delay/jitter: VoIP and online gaming
        • High throughput: bulk file transfer
      • Security/privacy
        • High security: online banking and e-commerce
        • High privacy: Web surfing
      • Scalability
        • Very scalable: global Internet reachability
        • Not so scalable: communication in small groups
    • Applications Within an Single ISP
      • Customized virtual networks
        • Security for online banking
        • Fast-convergence for VoIP and gaming
        • Specialized handling of suspicious traffic
      • Testing and deploying new protocols
        • Evaluate on a separate virtual network
        • Rather than in a dedicated test lab
        • Large scale and early-adopter traffic
      • Leasing virtual components to others
        • ISPs have unused node and link capacity
        • Can allow others to construct services on top
    • Economic Refactoring in CABO
      • Infrastructure providers: Maintain routers, links, data centers, and other physical infrastructure
      • Service providers: Offer end-to-end services ( e.g., layer 3 VPNs, SLAs, etc.) to users
      Infrastructure Providers Service Providers Today: ISPs try to play both roles, and cannot offer end-to-end services
    • Similar Trends in Other Industries
      • Commercial aviation
        • Infrastructure providers: Airports
        • Infrastructure: Gates, “hands and eyes” support
        • Service providers: Airlines
      E.g.: airplanes, auto industry, and commercial real estate PEK ATL JFK SFO
    • Communications Networks, Too!
      • Two commercial examples in IP networks
        • Packet Fabric: share routers at exchange points
        • FON: resells users’ wireless Internet connectivity
      • FON economic refactoring
        • Infrastructure providers : Buy upstream connectivity
        • Service provider : FON as the broker (
    • Enabling End-to-End Services
      • Secure routing protocols
      • Multi-provider Virtual Private Networks
      • Paths with end-to-end performance guarantees
      Today Cabo Competing ISPs with different goals must coordinate Single service provider controls end-to-end path
    • Research Challenges
    • Virtualized and Programmable Routers
      • Multiple routers on a single substrate
        • Multiple control planes
        • Multiple data planes
      • Design trade-offs
        • Speed: aggregate forwarding performance
          • Getting close to raw forwarding speed
        • Isolation: avoiding interference
          • Avoiding jitter and resource contention
        • Customization: programmability of the data plane
          • Moving beyond IPv4 packets and Ethernet frames
          • Software (e.g., Click) vs. hardware (e.g., NetFPGA)?
    • Control Frameworks
      • Embedding virtual topology in physical one
        • Finding suitable physical nodes and physical links
        • With enough CPU, bandwidth, and memory
        • … and satisfying geographic and delay constraints
      • Instantiating the virtual network
        • Creating each virtual node and virtual link
        • Reserving the necessary resources
      • Monitoring the running system
        • Detecting and diagnosing problems
        • Providing measurement data to virtual network
    • Ways to Exploit Router Virtualization
      • Exploiting the new capabilities in routers
        • Separation of the physical from the logical
        • Ability to run multiple routers in parallel
      • Example: virtual router migration
        • Moving router from one physical node to another
        • E.g., for planned maintenance or service roll-out
      • Example: bug-tolerant routers
        • Running multiple instances of routing software
        • … and “voting” to protect the system from bugs
    • Discussion: Internet vs. Pluralism
      • Internet architecture
        • End-to-end argument
        • Best-effort packet-delivery service
        • Narrow waist of IP
        • Separation of intradomain from interdomain
      • Virtualized programmable networks
        • Complete control within a virtual network
        • Programmable functionality inside the network
        • Different (virtual) networks for different services
    • Discussion: Experimental Infrastructure
      • How to evaluate research ideas?
        • Analysis
        • Simulation
        • Prototyping
        • Deployment studies
      • Importance of wide-area deployment?
        • Realistic traffic and network conditions
        • Real users and participation in experiments
      • How real does real need to get?
      • Will researchers bother to build and deploy?
        • Incentives for conducting this kind of research