live migration of an entire network (and its hosts)

Live Migration of an Entire Network (and its Hosts)

Eric Keller, Soudeh Ghorbani, Matthew Caesar, Jennifer Rexford

HotNets 2012

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Widely supported to help:• Consolidate to save energy• Re-locate to improve performance

Virtual Machine Migration

Hypervisor

Apps

OS

Hypervisor

Apps

OS

Apps

OS

Apps

OS

Apps

OS

Apps

OS

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Many VMs working together

But Applications Look Like This

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Networks have increasing amounts of state

And Rely on the Network

Configuration Learned Software-Defined

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Joint (virtual) host and (virtual) network migration

Ensemble Migration

No re-learning,No re-configuring,No re-calculating

Capitalize on redundancy

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Some Use Cases

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• Customer driven – for cost, performance, etc.• Provider driven – offload when too full

1. Moving between cloud providers

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• Reduce energy consumption(turn off servers, reduce cooling)

2. Moving to smaller set of servers

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• Migrate ensemble to infrastructure dedicated to testing (special equipment)

3. Troubleshooting

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Automated migration according to some objectiveand easy manual migration

Goal: General Management Tool

Monitoring

Objective

Migration

Ensemble Migration

Automation

manual

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LIve Migration of Ensembles

Migration Primitives

Migration Orchestration

Tenant Control

LIMENetwork Virtualization

API to operator/ automation

Software-defined networkVirtualized servers

Tenant Control

virtual topology Migration is transparent

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Why Transparent?

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Separate Out FunctionalityTenant Control

Network Virtualization

Tenant Control

virtual topology

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Separate Out Functionality

Migration Primitives

Migration Orchestration

Tenant Control

Network Virtualization

Tenant Control

virtual topology

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Multi-tenancy

Migration Primitives

Migration Orchestration

Tenant Control

Network Virtualization

Tenant Control

virtual topology

InfrastructureOperator

Tenants

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Can we base it off of VM migration?• Iteratively copy state• Freeze VM• Copy last delta of state• Un-freeze VM on new server

How to Live Migrate an Ensemble

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Applying to Ensemble

Iterative copy

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Applying to Ensemble

Freeze and copy

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Applying to Ensemble

Resume

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Applying to Ensemble

Resume

Complex to implementDowntime potentially large

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Applying to Whole Network

Iterative copy

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Applying to Whole Network

Freeze and copy

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Applying to Whole Network

Resume

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Applying to Whole Network

Resume

Lots of packet lossLots of “backhaul” traffic

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Applying to Each Switch

Iterative copy

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Applying to Each Switch

Freeze and copy

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Applying to Each Switch

Resume

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Applying to Each Switch

Resume

Bursts of packet lossEven more “backhaul” traffic

Long total time

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• Clone the network• Migrate the VMs individually (or in groups)

A Better Approach

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Clone the Network

Copystate

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Clone the Network

Cloned Operation

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Clone the Network

MigrateVMs

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Clone the Network

MigrateVMs

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• Minimizes backhaul traffic• No packet loss associated with the network

(network is always operational)

Clone the Network

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• Same guarantees as migration-free

• Preserve application semantics

Consistent View of a Switch

Migration Primitives

Migration Orchestration

Network Virtualization

Switch_A_0 Switch_A_1

Switch_A

Application view

Physical reality

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Sources of Inconsistency

Switch_A_0 Switch_A_1

Apps

OS

Packet 0 Packet 1

R1R2

R1R2

Migration-free: packet 0 and packet 1 traverse same physical switch

VM(end host)

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1. Local Changes on Switch

Switch_A_0 Switch_A_1

(e.g. delete rule after idle timeout)

Apps

OS

Packet 0 Packet 1

R1R2

R1R2

VM(end host)

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2. Update from Controller

Switch_A_0 Switch_A_1

Apps

OS

Packet 0 Packet 1

R_newR1R2

R1R2

Install(R_new)

(e.g. rule installed at different times)

VM(end host)

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3. Events to Controller

Switch_A_0 Switch_A_1

Apps

OS

Packet 0Packet 1

R1R2

R1R2

Packet-in(pkt 0)

Packet-in(pkt 1)(received at controller first)

(e.g. forward and send to controller)

VM(end host)

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Consistency in LIME

Migration Primitives

Migration Orchestration

Network Virtualization

Switch_A_0 Switch_A_1

Switch_A

*Restrict use of some features* Use a commit protocol

* Emulate HW functions* Combine information

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• LIME is a general and efficient migration layer• Hope is future SDN is made migration friendly

• Develop models and prove correctness– end-hosts and network– “Observational equivalence”

• Develop general migration framework– Control over grouping, order, and approach

Conclusions and Future work

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• Eric Keller: eric.keller@colorado.edu• Soudeh Ghorbani: ghorban2@illinois.edu

Thanks