Network Virtualization

1. Network Virtualization Jennifer Rexford Advanced Computer Networks http://www.cs.princeton.edu/courses/archive/fall08/cos561/ Tuesdays/Thursdays 1:30pm-2:50pm

2. 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

3. 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… 

4. 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?

5. 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

6. 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

7. 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 1 2 3 sender receiver

8. 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”

9. 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-endservices in parallel • Over equipment owned by different parties

10. Pluralist Future

11. 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

12. 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

13. 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

14. 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

15. Similar Trends in Other Industries • Commercial aviation • Infrastructure providers: Airports • Infrastructure: Gates, “hands and eyes” support • Service providers: Airlines JFK SFO PEK ATL E.g.: airplanes, auto industry, and commercial real estate

16. Broker 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(www.fon.com)

17. 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

18. Research Challenges

19. 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)?

20. 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

21. 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

22. 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

23. 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