An Introduction to Overlay NetworksPlanetLab: A Virtual Overlay Network Testbed

Suhas Mathursuhas@winlab.rutgers.edu

Communication Networks II Spring 2005

Talk Outline

Introduction: The future internet & related challengesOverlay Networks Planet Lab

What is PlanetLab ? Infrastructure and working conceptsThe purpose of PlanetLabPlanetLab OS Architecture Goals

Concluding remarks

Introduction

Innovator’s Dilemma

The Internet is an enormous success storyCommerciallyImpact on our daily livesGlobal reach

Success has an unexpected cost: ossificationDifficult to deploy disruptive technology* (e.g.. IP Multicast)

Correct vulnerabilitiesIntroduce new capabilities

* A technology that would require major changes in the current internet.

Present day applications that require "disruption“:1. Application that may require Customized Routing 2. Peer-to-peer file sharing3. Content Distribution

These evolving applications require major changes in the internet (e.g. more intelligent routers).This change is resisted for obvious reasons (financial, etc) !!

Overlay Networks

What is an Overlay Network ?A logical network on top of the physical network.

Purpose-built virtual networks that use the existing Internet for transmission

The Internet was once deployed as an overlay on top of the telephony network

Overlay Networks: P2P example

Single Point of failurePerformance Bottleneck

Centralized Directory P2P Overlay (Napster Model) Hierarchical P2P Overlay

(KaZaa Model)

Overlay Networks: CDNThe First and the Last Mile

Peering Points

CDN company installs hundreds of servers throughout the Internet, typically placing them in lower-tier ISPs and Web hosting centers

Customer data is replicated on CDN servers; when a customer data is updated, the CDN network refreshes the contents on its (cache) servers

A CDN server contains data from many different content providers

DNS/ HTTP redirection in order to guide browsers to the right server

Motivation for a virtual overlay testbedThe research community is teeming with innovative planetary-scale applications and servicesOverlays offer an attractive way to introduce disruptive technology into the Internet, but…

There is a high barrier-to-entryThe next Internet will be created as an overlay on the current oneThere is NO vehicle to try out the next great ideas in this area (Enter )

PlanetLab

What is PlanetLab ?

A collection of machines distributed over the globePlanetLab currently consists of 565 machines, hosted by 266 sites, spanning over 25 countries.

An overlay network testbedResearchers can experiment with a variety of planetary-scale servicesserves as a meta testbed

A deployment platformProvides seamless migration of an application from early prototype to a popular service that continues to evolve

A microcosm of the next InternetSupports the introduction of disruptive technologies into the Internet through the use of overlay networks

A consortiumA collection academic, industrial, and government institutions

Unfortunately no one can be told what PlanetLab is.. You have to see it for yourself!

Nodes

565 machines, hosted by 266 sites, spanning over 25 countries

All of the machines are connected to the Internet. The goal is for PlanetLab to grow to 1,000 widely distributed nodes

Current University Nodes

Current University Nodes

The PlanetLab Architecture

Internet

PrincetonRutgers

University

Intel Labs

Wash U

The PlanetLab Architecture

A PlanetLab user sees a private set of machines (nodes) on which he can run his applications (A slice)

User 1 User 2

The PlanetLab ArchitectureUsers are granted slices – Sets of nodes on which users get a portion of the resources

Internet

PrincetonRutgers

University

Intel Labs

Wash U

The PlanetLab Architecture

So, a PlanetLab user is using a set of distributed Virtual Machines (VMs)

User 1 User 2

PlanetLab OS Architecture Goals

PlanetLab OS Node Architecture Goals

SliceDistributed set of Virtual Machines treated as a single entity, providing the resources required by a single PlanetLab experiment

Provide a virtual machine for each service running on a node (a part of the total service slice)

Isolate virtual machines (Node Virtualization)

Allow maximal control over virtual machines

Allocation of resources to the VMsNetwork, CPU, memory, disk

Fair AllocationGuaranteed Allocation

VMM

Nod

e M

anag

er

PrivilegedServices

Un-privilegedServices

PlanetLab NodeArchitecture

Slices (VMs)

Loca

lA

dmin

PlanetLab Network ActorsResource Broker (per service)

Obtain tickets from agents on behalf of service managers

Service Managers (per service)Obtain tickets from brokerRedeem tickets with node managers to acquire resourcesIf resources can be acquired, start service

PlanetLab Network ActorsAgents (centralized)

Track nodes’ free resourcesAdvertise resources to resource brokersIssue tickets to resource brokers

Tickets may be redeemed with node managers to obtain the resource

Node manager (one per node)Create slices for service managers

When service managers provide valid ticketsAllocate resources for vservers

Resource Monitor (one per node)Track node’s available resourcesTell agents about available resources

Obtaining a Slice

Agent

Service Manager

Broker

Obtaining a Slice

Agent

Service Manager

BrokerResource Monitor

Obtaining a Slice

Agent

Service Manager

BrokerResource Monitor

Obtaining a Slice

Agent

Service Manager

BrokerResource Monitor

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

Resource Monitor

Resource Monitor

Obtaining a Slice

Agent

Service Manager

Brokerticket

Resource Monitor

Resource Monitor

ticket

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

ticket

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

ticket

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

ticket

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

ticket

ticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

ticket

ticketNode Manager

Node Manager

Obtaining a Slice

Agent

Service Manager

Brokerticket

Obtaining a Slice

Agent

Service Manager

Brokerticket

Concluding Remarks

Current projects runningMonitoring the Network's Health

Monitor the health of the Internet, including watching for anomalies (worms, DDoS) and diagnosing failures.

Routing Overlays: Find alternative routes through the Internet, for e.g., routes that better match the application's requirements, and routes that more quickly recover from failures.

Content Distribution NetworksThese applications distribute content (e.g., web pages, domain names) widely across the Internet, with the goal of improving system throughput under heavy load (e.g., flash crowds and DDoS attacks)

Internet InfrastructureProvide new services for the Internet at large. They may provide new and better replacements for existing Internet services, or they may integrate entirely new functionality into legacy services, or both.

Distributed Query ProcessingThese applications have grown out of the intersection of sensor nets and distributed databases. They allow users to submit queries about information reported by sensors distributed across Planetlab.

etc…

Overlay Testbeds“The X-Bone dynamically deploys and manages Internet overlays to reduce configuration effort and increase network component sharing. The X-Bone discovers, configures, and monitors network resources to create overlays over existing IP networks. “

“Develop and deploy advanced network applications and technologies, accelerating the creation of tomorrow’s Internet.”

Focus is on automated establishment and management of overlays

Allows multiple levels of virtualization but closely tied to current internet architecture

1. A large set of geographically distributed machines2. A realistic network substrate that experiences

congestion, failures, and diverse link behaviors3. Allows services and applications based on

architectures radically different from current arch. to be tested and evaluated

4. Serves as a deployment platform and a catalyst for bringing about necessary change to the present internet.

Live PlanetLab Node monitoring (Using Ganglia)*

Load, Memory, CPU usage and Network throughput for the last 1 Hour (29th APR 2005) at one of the 6 PlanetLab nodes currently at MIT:

* http://planetlab.millennium.berkeley.edu/ganglia_v2/

Questions ?

ReferencesOvercoming the internet impasse through virtualization: L. Peterson, S. Shenker, and J. Turner. Third Workshop on Hot Topics in Networking (HotNets-III) (November 2004).A Blueprint for Introducing Disruptive Technology into the Internet: Larry Peterson, Tom Anderson, David Culler and Timothy Roscoe, Proceedings of ACM HotNets-I Workshop, Princeton, New Jersey, USA, October 2002.Operating systems support for planetary-scale network services: Andy Bavier, Mic Bowman, Brent Chun, David Culler, Scott Karlin, Steve Muir, Larry Peterson, Timothy Roscoe, Tammo Spalink, and Mike Wawrzoniak: First Symposium on Networked Systems Design and Implementation (NSDI) (March 2004), 253-266

AcknowledgementsKishore Ramachandran, Grad Student, WINLAB, RutgersPravin Shankar, Grad Student, DISCO lab, CS Dept, Rutgers.