Exchange Points, Route Servers and Registries

[email protected] Exchange Points, Route Servers and Routing Registries

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Exchange Points, Route Servers and Registries

Abha [email protected]


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Objectives

To be able to explain what an exchange point isTo be able to explain why people use XPsTo understand why they are importantTo review some current exchange point designs

used todayTo think about how to set up an exchange point in

your environmentTo understand why Route Servers are usefulTo be able to explain what routing registries do

and why you should use one


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Introduction to Exchange Points

a bit of historyWhat are they?Why use them?


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A Bit of History…End of NSFnet - one major backbonemove towards commercial Internet

private companies selling their bandwidthneed for coordination of routing

exchange between providers Traffic from ISP A needs to get to ISP B

Routing Arbiter project created to facilitate this


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What is an Exchange Point?Network Access Points (NAPs)

established at end of NSFnet Major providers connect their

networks and exchange trafficHigh-speed network or switchSimple concept - where providers

come together to exchange traffic


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Exchange points

ISPs connect at Exchange Points or Network Access Points

to exchange traffic

XP 1 XP 2

ISP A

ISP B


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Conceptual Diagram of XP

Customer Router

Customer Router

Customer Router

Exchange Point Medium


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Why use an Exchange Point?Routers are attached to exchange trafficMLPA, bilateral, customer/transit

relationshipsExamples in U.S:

AADS Mae-East/Mae-West Pacbell PAIX


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Why XPs?Multiple service providersEach with Internet connectivity

InternetInternet

AA BB


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Why XPs?

Is not cost effectiveBackhaul issue causes cost to both

partiesInternetInternet

AA BB


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Why XPs?Domestic Interconnection

InternetInternet

AA BB


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Exchange Structures layer 2 models (the NAP or IX)

tailored bilateral policies


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Why use an Exchange Point?Peering

Shared medium vs. point-to-point Shared

can exchange traffic with multiple peers at one location via one interface

Point-to-Pointfor high volumes of traffic


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The Need for Exchanges

AS 2

AS 1

US

ASIA


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The Need for Exchanges

AS 2

AS 1

US

ASIA


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Why use an Exchange Point?KEEP LOCAL TRAFFIC LOCAL!!!

ISPs within a region peer with each other at local exchange

No need to have traffic go overseas only to come back


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Exchange Point DesignEthernetFDDIATMDesigns range from the simple to the

complex Fddi gigaswitches to ethernet switches


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When can an XP be a bad thing?

Too many exchange points in one region competing exchanges defeats the

purposeBecomes expensive for ISPs to

connect to all of them


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Exchange Point policies/politics

AUPsNobody is obliged to peerdon’t spoof


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Exchange Point etiquetteDon’t point defaultThird-party next-hopFilter! Filter! Filter!

Or do reverse path check


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Exchange Point examples

AADS (Ameritech) in Chicago, USA ATM switches

Pacbell in California, USA trunked (geographically diverse) ATM

switchesPAIX in Palo Alto, California, USA

Fddi gigaswitchesMAE West in California, USA

trunked Fddi gigaswitches


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Exchange Point examplesLINX in London, UK

Ethernet switchesAMS-IX in Amsterdam

Ethernet switchesNSPIXP-2 in Tokyo, Japan

Ethernet switches


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Features of XPsRedundancy

multiple switchessupport

NOC to provide 24x7 support for problems at the exchange

DNS, Routing Registries, NTP servers servers often colocated at these

centralized points


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Features of XPslocation

neutral colocation facilitiesaddress spaceASRoute serversstatistics


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More info about IXshttp://www.ep.nethttp://www.rsng.net


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Things to think about...Do you need to be at an Exchange

Point?Would you want to start an

Exchange Point?Would keeping local traffic local

benefit your ISP?Would your environment (politically,

etc.) support an Exchange Point?


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DiscussionHow would you build an exchange

point in your environment?Who would connect?What services would you provide?What policies would you enforce?What does your environment look

like? Is it feasible to set up an XP?


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Route Server BackgroundWhat is a Route Server?Features of a Route ServerAdvantages of using a Route ServerExchange Point Design with a Route

Server


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What is a Route Server?Unix box which runs Route Server

softwareExchanges routing information with

service provider routers at a NAP based on policy

Does not forward packets


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Route Server at an XP

NAP R3R2

R1

ROUTE SERVER


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Features of a Route ServerScalable RoutingSimplified Routing Processes on ISP

RoutersInsertion of RS Autonomous System

Number in the Routing Path


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Features of a Route Server (con)

Handling of Multi-Exit DiscriminatorRoute Flap Dampening MechanismUses Policy registered in IRR


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Diagram of N-squared Mesh


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With the Route Servers


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RS Exchange Point Routing Flow

TRAFFIC FLOW

ROUTING INFORMATION FLOW


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Advantages of Using a Route Server

Scalable RoutingSeparation of Routing and

ForwardingSimplify Routing Configuration

Management on ISPs routersEnforce Good Routing Engineering


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Advantages of Using a Route Server (con)

PREVENTS SPREAD OF BOGUS ROUTING INFORMATION!


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Peering with the Route Servers

Any ISP attached to a NAP can peer with the Route Servers

ISP must register their policy in the Internet Routing Registry

Must use BGP


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RSdRoute Server DaemonOriginally developed by ISI during RA

projectDeveloped from GateDMulti-vieweBGP onlyUses import-from only


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Things to think about...How would using a route server

benefit you?Consider setting one up yourself for

your community, or talk to Merit...


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Route Server Referenceshttp://www.rsng.nethttp://www.merit.edu/ipmahttp://www.isi.edu/ra


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What is the Routing Registry? contact names, email addresses and

telephone numbers for an AS routing policy for an AS (what other

ASes does it connect to, which routes do they exchange)

information about routes (most important is which AS originates the route)

several other types of information


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What is the Routing Registry?Distributed database collectively

known as Internet Routing Registry (IRR) RADB, RIPE, CW, ANS, Canet

Providers register routing policyUsed for planning, debugging and

generating backbone router configshttp://www.radb.net/


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What is the Routing Registry?Can be used by anyone worldwide

debugging configuring engineering routing addressing


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What happens if I don’t use a database?

Routing Horror Stories AS7007 announcing bogus routes


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So, I need to use the database because…..

Filters generated off the IRR protect against inaccurate routing information

Makes troubleshooting and debugging easier

Keep track of policySecurityFilter! Filter! Filter!!


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Why Bother with all of this?View of global routing policy in a single

cooperatively maintained databaseto improve integrity of Internet’s

routinggenerate router configs

protect against inaccurate routing info distribution

verification of Internet routing


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Why Bother using the database (con)

Many providers require that you register your policy (or they won’t peer with you)


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Policy Languagesexpress policy with aut-num objects,

route objects, AS-MACROScurrently RIPE-181moving to RPSL

more policy control


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What is RPSL?Routing Policy Specification

LanguageDesigned to replace current

language (RIPE-181)Enhanced and more generalized


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How does the language work?

Object-orientedExpress policy in objects

person mntner role aut-num route

Can make sets of objects


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Describing PolicyUse the language to describe your

relationship with other Peers routes importing routes exporting specific policies

interfaces, MEDs, communities


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Querying the Databasewhois -h whois.radb.net AS237whois -h whois.radb.net MAINT-

AS237whois -h whois.radb.net

198.108.60.0


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How to Register your IRR policy

Register one or more maintainersRegister AS and policy informationRegister RoutesDescribes your import and export

policy At the very least, provides contact

information


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Register your maintainer

mntner: MAINT-AS237descr: Maintainer for AS 237admin-c: Abha Ahujaupd-to: [email protected]: [email protected]: MAINT-AS237auth: MAIL-FROM [email protected]: [email protected] 941219source: RADB


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Register your Routes

route: 35.0.0.0/8descr: Merit Network, Inc.descr: University of Michigandescr: 4251 Plymouth Road, Suite Cdescr: Ann Arbordescr: MI 48105-2785, USAorigin: AS237mnt-by: MAINT-AS237changed: [email protected] 931113source: RADB


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Register your aut-numDescribe your policy!Peering relationshipsimport-fromexport-tocan use AS-sets


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Register your aut-num (con)aut-num: AS237as-name: MICHNET-ASNdescr: MichNet Primary ASdescr: Merit Network Inc.descr: Ann Arbor, MI USAas-in: AS3561 accept ANYas-out: AS3561 announce AS237admin-c: JMD24tech-c: JMD24notify: [email protected]: MERIT-MAINT-MCIchanged: [email protected] 980202source: CW


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Register your aut-num (con)

as-set: AS237:AS-CUSTOMERSdescr: ASs for which MichNet provides descr: transit servicemembers: AS229,AS237,AS238,AS7016,AS10330tech-c: MichNet NOCadmin-c: MichNet NOCremark: transit ASs of MichNetnotify: [email protected]: MAINT-AS237changed: [email protected] 990222source: RADB


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Router ConfigurationCurrently configs by hand - slow and

inaccurateConfiguring routers using the IRR

lots of tools available!!! RtConfig by ISI

route and Aspath filters.Import and export

Filtering is a good thing...


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Router ConfigurationCurrently configs by hand - slow and

inaccurateConfiguring routers using the IRR

lots of tools available!!!Filtering is a good thing... Plans for some routers to support

RPSL directly


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Router Configuration

SD

GRF 400

IR R

IRR Database Server

Configuration Machine


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How do I use the IRR to generate configs?

Tools available to generate config files gated rsd Cisco

RAToolSet http://www.isi.edu/ra/RAToolSet RtConfig Aoe, Roe


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RIPE181 whois queries, flags, objects RPSL whois queries, flags, objects Complete support for RAToolSet

queries (fast!) Cisco configuration and management

interface Complete automated mirroring support

What does the RADB support now?


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How do I participate?Set up your own registry

Private for your ISP? Community for the region? Download the software (IRRd)

Use the RADB


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Things to think about...How would you register your policy?

Try to describe it in an aut-num objectHow would registering your policy

benefit you? The community?


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Resourceshttp://www.radb.nethttp://www.irrd.nethttp://www.isi.edu/ra/rpshttp://www.isi.edu/ra/RAToolSethttp://www.ietf.org/html.charters/rps-

charter.htmlhttp://www.rsng.nethttp://www.ripe.net


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SpecificsRegister your policy in the RADB

Merit can assist ([email protected])Questions? Need help?

[email protected] [email protected]

Documents

Exchange Points, Route Servers and Registries