1

VINI: Virtual Network Infrastructure

Jennifer Rexford

Princeton University

http://www.cs.princeton.edu/~jrex

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

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?

4

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

5

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

6

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

7

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”

8

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

9

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

10

VINI: VIrtual Network Infrastructure

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

Network Events

Observed in operational network

Inject faults, anomalies

12

Fixed Infrastructure

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

13

Shared Infrastructure

Experiments given illusion of dedicated hardware

14

Flexible Topology

VINI supports arbitrary virtual topologies

15

Network Events

VINI exposes, can inject network failures

16

External Connectivity

s

c

Experiments can carry traffic for real end-users

17

External Routing Adjacencies

s

c

BGP

BGP

BGP

BGP

Experiments can participate in Internet routing

18

VINI Platform Design

19

Virtualizing the Computer

• Starting with the PlanetLab software–Each experiment has its own virtual machine –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

20

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 virtual machine

XORP(routing protocols)

VM

21

Virtual Network Abstraction

• PlanetLab limitation:– Does not virtualize the

underlying network

• For each VM we want– Interfaces, bound to

tunnels to other nodes– Networking stack (e.g.,

forwarding table)– Packet forwarding in OS

• Across VMs we want– Independent topologies– Resource isolation

XORP(routing protocols)

eth1 eth3eth2eth0

FIB

Control

Data

User space

OS

tunnels

22

Network Name Spaces (NetNS)

• NetNS extension to Linux–Virtualizes the network stack–Each network stack bound to user process(es)

• Provides us with –Separate forwarding table (FIB)–Separate interfaces

• But, a few challenges remain–Connecting interfaces to tunnels–Supporting non-IP protocols–Providing isolation between virtual nodes

23

Connecting Interfaces to Tunnels

• Ethernet switch– Linux bridge module– Connects all interfaces– And all tunnels

• Short bridge – No MAC learning– No forwarding look-up– No frame header copying

• EGRE tunnels– Carry Ethernet frames– Support non-IP protocols

XORP(routing protocols)

eth1 eth3eth2eth0

Short Bridge

etun3etun2etun1FIB

User space

OS

24

Isolation Between Virtual Networks

• Virtual host (user space)– Experimenter’s software– Protocols, applications

• Virtual host (OS)– Forwarding tables– Virtual Ethernet interfaces

• Shared substrate (OS)– Tunnels between nodes– Enforcing rate limits

XORP(routing protocols)

eth1 eth3eth2eth0

Short Bridge

etun3etun2etun1FIB

User space

OS

OS

25

Ongoing Work on Packet Forwarding

• Tension between three goals–High-speed packet forwarding–Customization of the data plane–Sharing of the data plane

• Step #1: Greater flexibility–Customized data planes in the kernel–Virtualizing Click to support different virtual hosts

• Step #2: Greater speed–Customized data planes in an FPGA–Virtualizing the NetFPGA board from Stanford

26

Example Experiment on VINI

27

Intra-domain Route Changes

s

c

1176

587 846

260

700

6391295

2095

902

548

233

1893

366

Watch OSPF route convergence on Abilene

856

28

Ping During Link Failure

70

80

90

100

110

120

0 10 20 30 40 50

Pin

g R

TT

(m

s)

Seconds

Link down Link up

Routes converging

Abilene RTT: 73ms

29

TCP Throughput

0

2

4

6

8

10

12

0 10 20 30 40 50

Meg

abyt

es t

rans

ferr

ed

Seconds

Packet receiv ed

Zoom in

Link down Link up

30

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

31

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…

32

Where does all this experimentation lead us?

33

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

34

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

35

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

36

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

37

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

PEKATL

JFK

SFO

38

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

39

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

40

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