Transcript presentation source - Workshops

Internet Exchange Points
(IXPs)
Philip Smith
E2 Workshop, AfNOG 2005
Objectives





To be able to explain what is an exchange
point
To be able to explain why ISPs participate in
IXPs
To understand why IXPs are important
To review some current IXP designs used
today
To think about how to set up an exchange
point in your environment
Introduction to Internet
Exchange Points



A bit of history
What are they?
Why use them?
A Bit of History…


End of NSFnet – one major backbone
move towards commercial Internet


need for coordination of routing
exchange between providers


private companies selling their bandwidth
Traffic from ISP A needs to get to ISP B
Routing Arbiter project created to
facilitate this
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 ethernet switch
Simple concept – any place where providers
come together to exchange traffic
Internet Exchange Points
ISP A
XP 1
XP 2
ISP B
ISPs connect at Exchange Points or
Network Access Points to exchange traffic
Conceptual Diagram of an IXP
Exchange Point Medium
ISP Router
ISP Router
ISP Router
Why IXPs?


Multiple service providers
Each with Internet connectivity
Internet
A
B
Why IXPs?


Is not cost effective
Backhaul issue causes cost to both
parties
Internet
A
B
Why IXPs?

Domestic Interconnection
Internet
A
B
Exchange Structures

layer 2 models (the NAP or IXP)

tailored bilateral policies
Why use an IXP?

PEERING


Shared medium vs. point-to-point
Shared


can exchange traffic with multiple peers at one
location via one interface
Point-to-Point

for high volumes of traffic
Why use an IXP?

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
Much reduced latency and increased
performance
Why use an IXP?

SAVES MONEY!!!


Traffic going overseas means transit
charges paid to your upstream ISP
Money stays in local economy


Used to provide better local infrastructure and
services for customers
Customers pay less for Internet access


Therefore more customers sign up
ISP has more customers, better business
Why use an IXP?

VASTLY IMPROVES PERFORMANCE!!!



Network RTTs between organisations in the
local economy is measured in milliseconds,
not seconds
Packet loss becomes virtually non-existent
Customers use the Internet for more
products, services, and activities
Why use an IXP?





Countries or regions with a successful
IXP have a successful Internet economy
Local traffic stays local
Money spent on local ‘net infrastructure
Service Quality not an issue
All this attracts businesses, customers,
and content providers
The Need for Exchanges
AS 1
US
AFRICA
AS 2

Local traffic travels via the US
The Need for Exchanges
AS 1
US
AFRICA
AS 2

Keep Local Traffic Local!
Exchange Point Design


Ethernet switch
Has superseded all other types of
network devices for an IXP


From the cheapest and smallest 12 or 24
port 10/100 switch
To the largest 32 port 10GigEthernet
switch
What can go wrong?

Too many exchange points in one
region


competing exchanges defeats the purpose
Becomes expensive for ISPs to connect
to all of them
 An IXP is not a competition, it’s not a
business
What can go wrong?



IXPs try to compete with their membership
IXPs run as a closed privileged club
For example:




Interconnecting IXP locations with their own
transit service
Providing access to end users rather than just
Service Providers
Restrictive membership criteria (closed shop)
Interfering with ISP business decisions e.g.
Mandatory Multi-Lateral Peering
Exchange Point
policies/politics

AUPs



Fees?




Acceptable Use Policy
Minimal rules for connection
Some IXPs charge no fee
Other IXPs charge cost recovery
A few IXPs are commercial
Nobody is obliged to peer

Agreements left to ISPs, not mandated by IXP
Exchange Point etiquette




Don’t point default route at another IXP
participant
Be aware of third-party next-hop
Only announce your aggregate routes
Filter! Filter! Filter!

And do reverse path check
Exchange Point examples

LINX in London, UK


AMS-IX in Amsterdam, NL


Ethernet switches
Ethernet switches
JPNAP in Tokyo, Japan

Ethernet switches
Exchange Points in Africa










CR-IX – Cairo, Egypt
iBiX – Ibadan, Nigeria
JINX – Johannesburg, South Africa
KINIX – Kinshasa, Dem Rep of Congo
KIXP – Nairobi, Kenya
MOZIX – Maputo, Mozambique
RINEX – Kigali, Rwanda
SZIXP – Mbabane, Swaziland
TIX – Dar es Salaam, Tanzania
UiXP – Kampala, Uganda
Source: http://www.nsrc.org/AFRICA/afr_ix.html
Features of IXPs

Redundancy


Support


multiple switches
NOC to provide 24x7 support for problems at the
exchange
DNS, Route Collector, Content & NTP servers



CCTLD servers
Content redistribution systems such as Akamai
Route Collector – Routing Table view
Features of IXPs

Location


Address space



Peering LAN
AS


neutral co-location facilities
If using Route Server
(Route servers)
Statistics

Traffic data – for membership
More info about IXPs

http://www.ep.net/ep-main.html


Excellent resource for ip address allocation
for exchanges, locations of XPs in the
world, AUPs and other policies
http://www.pch.net/documents

Another excellent resource of IXP locations,
papers, IXP statistics, etc
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?
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 IXP?
Important to Remember...


Exchange Points can be as simple as an
ethernet HUB!!!!
Keeping local traffic local



improves performance
cheaper
often simple to do!
Exercise
Building an IXP
AS100
AS200
BGP to
provider
AS 1
AS 2
AS 3
AS 4
AS 5
AS 6
AS 7
AS 8
AS 9
AS 10
196.200.220.224/28
SWITCH
AS 1
AS 2
AS 3
AS 4
AS 5
AS 6
AS 7
AS 8
AS 9
Ethernet
to IXP
AS 10
Introduction to Route
Collectors
Route Collector Background




What is a Route Collector?
Features of a Route Collector
Purpose of a Route Collector
IXP Design with a Route Collector
What is a Route Collector?



Usually a router or Unix box running
BGP
Gathers routing information from
service provider routers at an IXP
Does not forward packets
Purpose of a Route Collector

To provide a public view of the Routing
Information available at the IXP



Useful existing members to check
functionality of BGP filters
Useful for prospective members to check
value of joining the IXP
Useful for the Internet Operations
community for troubleshooting purposes

E.g. www.traceroute.org
Route Collector at an IXP
R1
R2
IXP
ROUTE Collector
R3
Route Collector Requirements


Router or Unix system running BGP
Peers eBGP with every IXP member




Accepts everything; Gives nothing
Uses a private ASN
Connects to IXP Transit LAN
“Back end” connection


Second Ethernet globally routed
Connection to IXP Website for public
access
Route Collector
Implementation




Most IXPs now implement some form of
Route Collector
Benefits already mentioned
Great public relations tool
Unsophisticated requirements

Just runs BGP
Introduction to Route Servers
Route Collector plus more
Route Server Background




What is a Route Server?
Features of a Route Server
Advantages of using a Route Server
Exchange Point Design with a Route
Server
What is a Route Server?


All the features of a Route Collector
But also:


Announces routes to participating IXP
members according to their routing policy
definitions
Implemented using the same
specification as for a Route Collector
Features of a Route Server






Helps scale routing
Simplifies Routing Processes on ISP
Routers
Insertion of RS Autonomous System
Number in the Routing Path
Handling of Multi-Exit Discriminator
Route Flap Damping
Uses Policy registered in IRR
Diagram of N-squared Mesh
With the Route Servers
RS based Exchange Point
Routing Flow
TRAFFIC FLOW
ROUTING INFORMATION FLOW
Advantages of Using a Route
Server





Helps scale Routing
Separation of Routing and Forwarding
Simplify Routing Configuration
Management on ISPs routers
Enforce Good Routing Engineering
Helps prevent the spread of bogus
routing information!
Disadvantages of Using a
Route Server



ISPs lose direct policy control
Dependent on 3rd party for
configuration and troubleshooting
Insertion of RS Autonomous System
Number in the Routing Path
Peering with the Route
Servers


Any ISP attached to an IXP can peer
with the Route Servers
ISP must register their policy in the
Internet Routing Registry


Most IXPs who provide the RS facility also
provide a local IRR for policy registration
Must use BGP
Things to think about...

Would using a route server benefit you?


Helpful when BGP knowledge is limited
Avoids having to maintain a large number
of eBGP peers
Introduction to the IRR
The Internet Routing Registry
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
What is the Routing Registry?

Distributed database collectively known
as Internet Routing Registry (IRR)




APNIC, RIPE, ARIN, RADB, etc
http://www.irr.net/docs/list.html
Providers register routing policy
Used for planning, debugging and
generating backbone router configs
What is the Routing Registry?

Can be used by anyone worldwide




debugging
configuring
engineering routing
addressing
What happens if I don’t use
the IRR

Routing Horror Stories



AS7007
announcing bogus routes
Inconsistent policy at network borders


Peers and upstreams need physical
notification of policy changes
Mistakes easily made
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 policy
Security
Filter! Filter! Filter!!
Why Bother using the IRR?



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
Why Bother using the IRR?

Many providers require that you register
your policy (or they won’t peer with
you)
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
Querying the Database



whois -h whois.ripe.net AS702
whois -h whois.ripe.net AS1849-MAINT
whois -h whois.ripe.net 158.43.0.0
How to Register your IRR
policy




Register one or more maintainers
Register AS and policy information
Register Routes
Describes your import and export policy

At the very least, provides contact
information
Router Configuration


Currently configs by hand - slow and
inaccurate
Configuring routers using the IRR


lots of tools available!!!
IRRToolSet maintained by ISC



route and Aspath filters.
Import and export
Filtering is a good thing...
Router Configuration
IRR
Configuration
Machine
Router
IRR Database
Server
How do I use the IRR to
generate configurations


Tools available to generate config files
for most BGP implementations
IRRToolSet



http://www.isc.org/sw/IRRToolSet/
Started off as RAToolSet as a project of ISI
Moved to RIPE NCC custodianship and
became IRRToolSet


Enhanced to support RPSL (RFC2622)
Now maintained by ISC
How do I participate?

Set up your own registry




Private for your ISP?
Community for the region?
Download the software (from ISC)
Use one of the many public IRR
systems

Ask AfriNIC to set one up?
Things to think about...

How would you register your policy?


Try to describe it in an aut-num object
How would registering your policy
benefit you? The community?