Holly Brackett Pease USENIX NETA‘99 Challenges Deploying a Global Network Holly Brackett Pease Director, Network Engineering Digital Island

Holly Brackett PeaseUSENIX NETA‘99

Challenges Deploying a Global Network

Holly Brackett PeaseDirector, Network Engineering

Challenges Deploying a Global Network

Holly Brackett PeaseDirector, Network Engineering

Digital IslandDigital Island


Challenges Deploying A Global Network

• The Digital Island Solution• A Brief Overview of BGP• Challenges of Worldwide Routing

– Ensuring Routes Are Accepted– Tier-1 Provider Policies– BGP Limitations

• Logistics of Deploying a Global Environment


Audience

• Network Managers Homed to Multiple Internet Service Providers

• Network Managers building a Global Network

• Network Managers with International Internet Connectivity

• General Interest in Internet Routing


The Digital Island Problem

• Internet: A Collection of Autonomous Networks

• US-Centric Internet– In some regions of the world, country-country

traffic passes through the US

• Congested Internet Exchanges and NAPs

• Increased Demand for International Access


The Digital Island Solution

• A Private Global Network Built to Deliver QOS

• Bypasses Congested NAPs and Exchange Points

• One Hop to the World


The Digital Island Strategy

• Private Backbone• Geographic-based Routing• Peer with Tier-1 International Partners

– Partners distribute routes in-country


A Brief Overview of BGP

• Backbone protocol of the Internet– Used by providers to Advertise Routes, Attempt

to Get Best Paths– Routes Exchanged by Peers using Autonomous

System Numbers

• BGP Rules– Local Pref– AS Hops– MEDs– Lowest Router ID


Challenges of Worldwide Routing

• Ensuring Routes are Accepted• Providing Predictable Routing

Paths• Limitations of BGP


Ensuring Routes are Accepted

• Transit Traffic ParanoiaTransit: Traffic that is not destined to or from a

given provider’s customers, yet crosses that provider’s backbone

– Policy 1: Only Accept Routes Originating from Direct Peers

– Policy 2: Transit Agreements – Policy 3: Restrict Number of AS Hops on routes

received from Peers– Policies usually Managed at Internet Exchanges



• Transit Traffic Paranoia (cont’d)– Some downstream providers choose “none of the

above”• Want to maintain market share in countries -

no direct peering with in-country peers • Don’t want to pay for Transit Agreements• If No Direct Peers, Policy #3 is useless

– 3 Solutions:– Ask nicely– Pay to Peer– Suffer the Consequences



• A Government-regulated Internet Exchange

• Israel’s IIX– operated by Israeli Internet Society (ISOC-IL)– non-profit– regulated by Ministry of Communications

• Strict Local Policies– Only accepts Israeli-registered routes


Providing Predictable Routing Paths

• Control Your Advertisements– Send Metrics– Use Specifics– No-Export

• US Tier-1 Providers: Private Peering– Inconsistent– Congested Pipes



• C&W (previously mci.net) Routing Policy– Local Pref All Routes Received from Customer Peers– Problem: Some US-based Downstream providers

hear Digital Island through International Points • equal AS Hops

– Solution: Force Peers who are C&W customers not to Advertise to C&W

• UUNET– No local-pref default, but similar policy for

controlling routing within net



• BGP Limitations– BGP Routing Extremely Limited– Metrics, Local Pref, AS Hops, Specific

Advertisements extremely limited tools– Does not account for link speeds,

congestion


Every Day Application

• Multi-homed Environment– Understand your provider’s routing policies– Control your Advertisements– Learn the “true” best route and operate

accordingly

• International Internet Connectivity– Advertise Specifics– Use Geographic AS’s


Every Day Application

• International Application Deployment– Understand your provider’s connectivity– Test your provider– Make your provider work for you


Logistics of Deploying a Global Environment

• International Carriers– Americans are in such a hurry– What’s an NTU?– X.21 is not a movie rating– Be precise about the interface you expect; then

pray

• Customary Problems– Are you ready?– Value-Added Tax– Who shipped what, when?


Logistics of Deploying a Global Environment

• There’s no Fry’s in Europe– You don’t accept VISA?– Anixter is your friend (this is not an

endorsement)

• Everything takes twice as long as you thought it would

Documents

Holly Brackett Pease USENIX NETA‘99 Challenges Deploying a Global Network Holly Brackett Pease Director, Network Engineering Digital Island