1. 1 VINI: Virtual Network Infrastructure Jennifer Rexford Princeton University http://www.cs.princeton.edu/~jrex

2. 2 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… 

3. 3 Internet is Showing Signs of Age Security –Weak notions of identity that are easy to spoof –Protocols that rely on good behavior Mobility –Hierarchical addressing closely tied with routing –Presumption that communicating hosts are connected Availability –Poor visibility into underlying shared risks –Multiple interconnected protocols and systems Network management –Many coupled, decentralized control loops

4. 4 Variety of Architectural Solutions Revisiting definition & placement of function –Naming, addressing, and location –Routing, forwarding, and addressing –Management, control, and data planes –End hosts, routers, and operators Designing with new constraints in mind –Selfish and adversarial participants –Mobile hosts and disconnected operation –Large number of small, low-power devices –Ease of network management

5. 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. 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. 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 senderreceiver 123

8. 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. 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-end services in parallel –Over equipment owned by different parties

10. 10 Three Projects: GENI, VINI, CABO Global Environment for Network Innovations –Large initiative for a shared experimental facility –Jointly between NSF CISE division & community –Distributed systems, wireless, optics, backbone VIrtual Network Infrastructure –Baby step toward the design of GENI –Systems research on network virtualization Concurrent Architectures Better than One –Clean-slate architecture based on virtualization –Economic refactoring for end-to-end services See http://www.geni.net and http://www.vini-veritas.net

11. 11 VINI Offers “Controlled Realism” Start with a controlled experiment Relax constraints, study effects Result: an operational virtual network that’s –Feasible –Valuable –Robust –Scalable, etc. Topology Actual network Arbitrary, emulated Traffic Real clients, servers Synthetic or traces Traffic Real clients, servers Synthetic or traces Network Events Observed in operational network Inject faults, anomalies

12. 12 Fixed Infrastructure Deployed VINI nodes in National Lambda Rail and Abilene, and PoPs in Seattle and Virginia

13. 13 Shared Infrastructure Experiments given illusion of dedicated hardware

14. 14 Flexible Topology VINI supports arbitrary virtual topologies

15. 15 Network Events VINI exposes, can inject network failures

16. 16 External Connectivity s c Experiments can carry traffic for real end-users

17. 17 External Routing Adjacencies s c BGP Experiments can participate in Internet routing

18. 18 Virtualizing the Computer Starting with the PlanetLab software –Simultaneous experiments in separate VMs –Each has “root” in its own VM, can customize –Reserve processing resources per VM Virtual Machine Monitor (VMM) (Linux++) Node Mgr Local Admin VM 1 VM 2 VM n … PlanetLab node

19. 19 Creating the Virtual Topology Goal: real routing protocols on virtual network topologies Various routing protocols (BGP, OSPF, RIP, IP multicast) Run unmodified routing software in a PlanetLab VM XORP (routing protocols) PlanetLab VM

20. 20 User-Mode Linux: Environment Interface ≈ network PlanetLab limitation: –Does not virtualize the underlying network Level of indirection –Run routing software in UML environment –Create virtual network interfaces in UML XORP (routing protocols) UML eth1eth3eth2eth0 PlanetLab VM

21. 21 Click: Data Plane Interfaces  tunnels –Click UDP tunnels correspond to UML network interfaces Filters –“Fail a link” by blocking packets at tunnel Forwarding packets –Avoid UML overhead –Around 200 Mbps –Not good enough XORP (routing protocols) UML eth1eth3eth2eth0 Click Packet Forward Engine Control Data UmlSwitch element Tunnel table Filters PlanetLab VM

22. 22 Operating System Extensions Move data plane into the operating system –Higher speed, lower jitter, and better scalability Virtualize the network data structures –Separate forwarding table per virtual host Virtual links inside the operating system –Terminate tunnels inside the operating system –No data copying leads to fast packet forwarding Resource isolation –Apply traffic shaping to control resource usage

23. 23 Three-Level Design Virtual host, in user space –Experimenter’s software –Routing protocols, applications Virtual host, in the OS –Forwarding tables –Virtual Ethernet interfaces Shared substrate, in the OS –Tunnels between VINI nodes –Shaping to enforce rate limits Research experiment Forwarding table, Virtual interfaces Traffic shaping, Tunnel interfaces Network

24. 24 Intra-domain Route Changes s c 1176 587 846 260 700 639 1295 2095 902 548 233 1893 366 Watch OSPF route convergence on Abilene 856

25. 25 Ping During Link Failure Link downLink up Routes converging Abilene RTT: 73ms

26. 26 TCP Throughput Zoom in Link downLink up

27. 27 Arriving TCP Packets Slow start Retransmit lost packet VINI enables a virtual network to behave like a real network

28. 28 Other Example VINI Experiments Scaling Ethernet to a large enterprise Routing-protocol support for mobile hosts Network-layer support for overlay services Piggybacking diagnostic data on packets Multiple solutions to multiple problems…

29. 29 Theoretical Challenges In collaboration with Mung Chiang

30. 30 1. VINI Management Framework Managing individual nodes –Instantiates virtual nodes and virtual links –Configures the CPU and link schedulers –Monitors the behavior of the virtual nodes Instantiating virtual networks –Admission control Book-keeping of node and link resources –Topology embedding Finding available node and link resources

31. 31 Theory Angle: Network Embedding Virtual network embedding problem –Given a set of virtual network topologies –With node and link constraints –Assign physical nodes and paths Virtual network VINI substrate

32. 32 Theory Angle: Network Embedding Computationally intractable problem –Online problem, with node and link constraints Two possible approaches –Could work on effective heuristics –Or, change the problem to make it easier! Modifying the substrate to simply embedding –Splitting virtual link over multiple substrate paths –Migration of virtual links and virtual nodes With Mung Chiang, Yung Yi, and Minlan Yu

33. 33 2. Virtualization as a Deployment Platform Moving beyond experimental facilities –Helping providers run their networks better Customized virtual networks –Security for online banking –Fast-convergence for VoIP and gaming –Anonymity and throughput for Web 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

34. 34 Theory Angle: Virtualization Theoretical foundation for virtualization –Does running customized protocols in parallel make sense? –Or, does it waste resources, or add complexity? Example: supporting two classes of traffic –Two applications with different utility functions –E.g., delay-sensitive vs. throughput-sensitive –Where should the traffic go (routing)? –What source rates to use (congestion control)? One architecture or two?

35. 35 Theory Angles: Virtualization Layering as optimization decomposition –Formulate the joint optimization problem –Primal decomposition to generate the protocols  U 1 (x i 1 ) + i  U 2 (x i 2 ) i max R 1 x 1 + R 2 x 2 <= C  U 1 (x i 1 ) i max R 1 x 1 <= Y  U 2 (x i 2 ) i max R 2 x 2 <= C -Y Master problem

36. 36 Theory Angles: Virtualization Primal decomposition == Virtualization –Separable objectives for the two classes –Solve each subproblem independently –Dynamically adapt the share of resources Virtualization may indeed “make sense” –Design and run each protocol independently on its own virtual network –With cooperation between virtual networks to adapt the resource shares Ongoing work with Mung Chiang, Jiayue He, and Rui Zhang-Shen

37. 37 2. Virtualization for Economic Refactoring 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 ProvidersService Providers Today: ISPs try to play both roles, and cannot offer end-to-end services

38. 38 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 NRT ATL JFK SFO

39. 39 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) Broker

40. 40 3. Theory Angles: Many Questions Virtual network embedding –With multiple infrastructure providers –Auctions for virtual nodes and links? –Cooperation to create virtual links? Modeling of the economic landscape –Analogies to other fields can be dangerous –Does the economic factoring really make sense? –Appropriate incentives for service providers and infrastructure providers alike

41. 41 Conclusion The Internet needs to change –Security, mobility, availability, management, … We can overcome barriers to change –Enable realistic experimentation with new ideas –Enable multiple designs with different trade-offs –Enable end-to-end deployment of new services Network virtualization is the key –Run many research experiments in parallel –Offer customized end-to-end services in parallel VINI as an enabling experimental platform