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VINI: Virtual Network Infrastructure

Jennifer Rexford

Princeton Universityhttp://www.cs.princeton.edu/~jrex

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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…

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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

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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

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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

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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

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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 receiver1 2 3

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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”

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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

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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

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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

Network Events

Observed in operational network

Inject faults, anomalies

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Fixed Infrastructure

Deployed VINI nodes in National Lambda Rail and Abilene, and PoPs in Seattle and Virginia

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Shared Infrastructure

Experiments given illusion of dedicated hardware

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Flexible Topology

VINI supports arbitrary virtual topologies

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Network Events

VINI exposes, can inject network failures

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External Connectivity

s

c

Experiments can carry traffic for real end-users

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External Routing Adjacencies

s

c

BGP

BGP

BGP

BGP

Experiments can participate in Internet routing

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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++)

NodeMgr

LocalAdmin VM1 VM2 VMn…

PlanetLab node

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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

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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

eth1 eth3eth2eth0

PlanetLab VM

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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

eth1 eth3eth2eth0

Click

PacketForwardEngine

Control

DataUmlSwitch

element

Tunnel table

Filters

PlanetLab VM

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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

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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

Researchexperiment

Forwarding table,Virtual interfaces

Traffic shaping,Tunnel interfaces

Network

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Intra-domain Route Changes

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c

1176

587 846

260

700

6391295

2095

902

548

233

1893

366

Watch OSPF route convergence on Abilene

856

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Ping During Link Failure

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80

90

100

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120

0 10 20 30 40 50

Pin

g R

TT

(m

s)

Seconds

Link down Link up

Routes converging

Abilene RTT: 73ms

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TCP Throughput

0

2

4

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10

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0 10 20 30 40 50

Meg

abyt

es t

rans

ferr

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Seconds

Packet receiv ed

Zoom in

Link down Link up

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Arriving TCP Packets

2.1

2.15

2.2

2.25

2.3

2.35

2.4

2.45

17.5 18 18.5 19 19.5 20

Meg

abyt

es in

str

eam

Seconds

Packet receiv ed

Slow start

Retransmitlost packet

VINI enables a virtual networkto behave like a real network

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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

• <Insert your prototype system here>

• Multiple solutions to multiple problems…

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Theoretical Challenges

In collaboration with Mung Chiang

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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

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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

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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

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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

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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?

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Theory Angles: Virtualization• Layering as optimization decomposition

–Formulate the joint optimization problem–Primal decomposition to generate the protocols

U1(xi1) +

i U2(xi

2) imax

R1x1 + R2x2 <= C

U1(xi1) i

max

R1x1 <= Y

U2(xi2) i

max

R2x2 <= C -Y

Master problem

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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

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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 Providers Service Providers

Today: ISPs try to play both roles, and cannot offer end-to-end services

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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

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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

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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

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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