Download COS 217, Spring 2005 - Princeton University

VINI: Virtual Network Infrastructure
Jennifer Rexford
Princeton University
http://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… 
2
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?
3
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
4
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
1
sender
2
3
receiver6
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: VIrtual Network Infrastructure
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VINI Offers “Controlled Realism”
Arbitrary,
emulated
Actual
network
Topology
Synthetic
or traces
Real
clients,
servers
Traffic
Inject faults,
anomalies
Observed in
operational
network
Network Events
• Start with a controlled
experiment
• Relax constraints,
study effects
• Result: an operational
virtual network that’s
– Feasible
– Valuable
– Robust
– Scalable, etc.
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Fixed Infrastructure
Deployed VINI nodes in National Lambda Rail
and Abilene, and PoPs in Seattle and Virginia
12
Shared Infrastructure
Experiments given illusion of dedicated hardware
13
Flexible Topology
VINI supports arbitrary virtual topologies
14
Network Events
VINI exposes, can inject network failures
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External Connectivity
c
s
Experiments can carry traffic for real end-users
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External Routing Adjacencies
BGP
BGP
c
s
BGP
BGP
Experiments can participate in Internet routing
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VINI Platform Design
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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
Node
Mgr
Local
Admin
VM1
VM2
…
VMn
Virtual Machine Monitor (VMM)
(Linux++)
PlanetLab node
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Creating the Virtual Topology
XORP
(routing protocols)
• Goal: real routing
protocols on virtual
network topologies
• Various routing
protocols (BGP, OSPF,
RIP, IP multicast)
• Run unmodified
routing software
in a virtual machine
VM
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Virtual Network Abstraction
• PlanetLab limitation:
User
space
XORP
(routing protocols)
eth0
eth1
eth2
– Does not virtualize the
underlying network
• For each VM we want
eth3
Control
Data
FIB
– Interfaces, bound to
tunnels to other nodes
– Networking stack (e.g.,
forwarding table)
– Packet forwarding in OS
• Across VMs we want
tunnels
OS
– Independent topologies
– Resource isolation
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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
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Connecting Interfaces to Tunnels
User
space
XORP
(routing protocols)
eth0
eth1
eth2
eth3
• Ethernet switch
– Linux bridge module
– Connects all interfaces
– And all tunnels
• Short bridge
FIB
etun1
etun2
– No MAC learning
– No forwarding look-up
– No frame header copying
etun3
Short Bridge
• EGRE tunnels
OS
– Carry Ethernet frames
– Support non-IP protocols
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Isolation Between Virtual Networks
User • Virtual host (user space)
space
– Experimenter’s software
– Protocols, applications
XORP
(routing protocols)
eth0
eth1
eth2
eth3
• Virtual host (OS)
FIB
etun1
etun2
etun3
OS
– Forwarding tables
– Virtual Ethernet interfaces
• Shared substrate (OS)
Short Bridge
– Tunnels between nodes
– Enforcing rate limits
OS
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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
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Example Experiment on VINI
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Intra-domain Route Changes
s
856
2095
700
260
1295
c
639
366
233
548
587
846
902
1893
1176
Watch OSPF route convergence on Abilene
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Ping During Link Failure
Link down
120
Routes converging
110
Ping RTT (ms)
Link up
100
90
80
Abilene RTT: 73ms
70
0
10
20
30
Seconds
40
50
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TCP Throughput
Link down
12
Link up
Megabytes transferred
Packet receiv ed
10
8
6
4
Zoom in
2
0
0
10
20
30
40
50
Seconds
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Arriving TCP Packets
2.45
Megabytes in stream
Packet receiv ed
2.4
2.35
VINI
2.3
enables
Slow start a virtual network
to
behave
like
a
real
network
2.25
2.2
Retransmit
lost packet
2.15
2.1
17.5
18
18.5
19
Seconds
19.5
20
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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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Where does all this
experimentation lead us?
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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 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
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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 estate37
Communications Networks, Too!
• Two commercial examples in IP networks
– Packet Fabric: share routers at exchange points
– FON: resells users’ wireless Internet connectivity
Broker
• 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
Competing ISPs
with different goals
must coordinate
Cabo
Single service
provider controls
end-to-end path
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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
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