exchange points, route servers and routing registries1 exchange points, route servers and registries...

Exchange Points, Route Servers and Routing Registries

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Exchange Points, Route Servers and Registries

Abha [email protected]


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ObjectivesTo be able to explain what is an exchange

pointTo be able to explain why people use XPsTo understand why XPs are importantTo review some current XP 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 original “exchange points”

Major providers connect their networks and exchange traffic

High-speed network or switchSimple concept - anyplace 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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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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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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The Need for Exchanges

AS 2

AS 1

US

AFRICA


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The Need for Exchanges

AS 2

AS 1

US

AFRICA

Keep Local Traffic Local!


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Exchange Point Design

EthernetFDDIATMDesigns range from the simple to the

complex Fddi gigaswitches to ethernet switches

(or hubs!)


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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

AUPs acceptable use policy rules for connection

Fees?Nobody is obliged to peerDon’t spoof


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Exchange Point etiquette

Don’t point defaultThird-party next-hopFilter! Filter! Filter!

Or do reverse path check


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Exchange Point examplesPacbell in California, USA

trunked (geographically diverse) ATM switches

PAIX in Palo Alto, California, USA Fddi gigaswitches

SIX in Seattle Ethernet hub in someone’s machine room

JINX in Johannesburg Ethernet switch in ISP association

colocation facility


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Exchange Point examples

LINX in London, UK Ethernet switches

AMS-IX in Amsterdam Ethernet switches

NSPIXP-2 in Tokyo, Japan Ethernet switches


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Features of XPs

Redundancy multiple switches

support NOC to provide 24x7 support for

problems at the exchangeDNS, Routing Registries, NTP servers

servers often colocated at these centralized points


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Features of XPs

location neutral colocation facilities

address spaceASRoute serversstatistics


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More info about IXs

http://www.ep.net excellent resources about ip address

allocation for exchanges, locations of XPs in the world, AUPs and other policies

http://www.rsng.net route server and statistics resource


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Sample XPs

SIXMAE-LALINXHKIX


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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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Discussion

How 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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Important to Remember...

Exchange Points can be as simple as a HUB!!!!

Keeping local traffic local improves performance cheaper often simple to do!


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Exercise - The Benefits of Exchange Points


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C

A

BG

D

F

E

AS 100

AS 400

AS 1

AS 200 AS 1200

AS 1300

AS 300AS 1100

AS 2BGP to provider


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A

BG

C D

F

E

80.248.70.0/28

80.248.70.128/2880.248.70.144/28

80.2

48.7

0.20

8/28

80.2

48.7

0.19

2/28

80.248.70.160/28 80.248.70.176/28

80.248.70.224/28

SWITCH

Ethernet to IXP


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Route Server Background

What 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 software

Exchanges 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 Server

Scalable 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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RSd

Route Server DaemonOriginally developed by ISI during RA

projectDeveloped from GateDMulti-vieweBGP onlyUses import-from only


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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 References

http://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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Distributed database collectively known as Internet Routing Registry (IRR) RADB, RIPE, CW, ANS, Canet http://www.irr.net/docs/list.html

Providers register routing policyUsed for planning, debugging and

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


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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 database

to improve integrity of Internet’s routing

generate 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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Describing Policy

Use the policy languages to describe your relationship with other Peers routes importing routes exporting specific policies

interfaces, MEDs, communities

register routes with origin AS


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Querying the Database

whois -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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Router Configuration

Currently configs by hand - slow and inaccurate

Configuring 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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Currently configs by hand - slow and inaccurate

Configuring 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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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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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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Specifics

Register your policy in the RADB Merit can assist ([email protected])

Questions? Need help? [email protected] [email protected]


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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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