Network Virtualization

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Network Virtualization

• Jennifer Rexford
• Advanced Computer Networks
• http//www.cs.princeton.edu/courses/archive/fall08
  /cos561/
• Tuesdays/Thursdays 130pm-250pm

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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

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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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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?

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Hurdle 1 Deployment Dilemma

• An unfortunate catch-22
• Must deploy an idea to demonstrate feasibility
• Cant get an undemonstrated idea deployed
• A corollary the testbed dilemma
• Production network real users, but cant 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 isnt 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

1
2
3
sender
receiver
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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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Pluralist Future
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The Case for Pluralism

• Suppose we can break down the barriers
• Enable realistic evaluation of new ideas
• Overcome the coordination constraint
• Maybe there isnt just one right answer
• Maybe the problem is over-constrained
• Too many goals, some of them conflicting
• Maybe the goals change over time
• And well always be reinventing ourselves
• The only constant is change
• So, perhaps we should design for change

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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

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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

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Economic Refactoring in CABO
Infrastructure Providers
Service Providers

• 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

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

JFK
SFO
PEK
ATL
E.g. airplanes, auto industry, and commercial
real estate
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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)

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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
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Research Challenges
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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)?

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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

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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

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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

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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