Transcript IXPs - David Choffnes

CS 4700 / CS 5700
Network Fundamentals
Lecture 16: IXPs
(The Underbelly of the Internet)
REVISED 3/23/2015
Outline
 EMERGING INTERNET TRENDS
 INTERNET EXCHANGE POINTS
(IXPS)
2
The Internet as a Natural System
You’ve learned about the TCP/IP Internet
◦ Simple abstraction: Unreliable datagram transmission
◦ Various layers
◦ Ancillary services (DNS)
◦ Extra in-network support
So what does the Internet look like?
3
What does the Internet look like?
4
What does the Internet look like?
5
Characterization challenges
Limited measurements and models can hint at it
◦ Traceroute does not give us a complete view
◦ Gao-Rexford (policy routing) doesn’t capture everything
What is the Internet actually being used for?
◦ Emergent properties impossible to predict from protocols
◦ Requires measuring the network
◦ Constant evolution makes it a moving target
6
How is the Internet used?
7
How is the Internet used?
8
Measuring the capital-I Internet*
Measuring the Internet is hard
Significant previous work on
◦ Router and AS-level topologies
◦ Individual link / ISP traffic studies
◦ Synthetic traffic demands
But limited “ground-truth” on inter-domain traffic
◦ Most commercial arrangements under NDA
◦ Significant lack of uniform instrumentation
*Mainly borrowed stolen from Labovitz 2010
9
Conventional Wisdom (i.e., lies)
Internet is a global scale end-to-end network
◦ Packets transit (mostly) unmolested
◦ Value of network is global addressability /reachability
Broad distribution of traffic sources / sinks
An Internet “core” exists
◦ Dominated by a dozen global transit providers (tier 1)
◦ Interconnecting content, consumer and regional providers
10
Traditional view
Traditional Internet Model
Page 14 - Labovitz SIGCOMM 2010
11
Does this still hold?
Emergence of ‘hyper giant’ services
How much traffic do these services contribute?
Hard to answer!
◦ Reading: Labovitz 2010 tries to look at this.
12
How do we validate/improve this picture?
Measure from
◦ 110+ ISPs / content providers
◦ Including 3,000 edge routers and 100,000 interfaces
◦ And an estimated ~25% all inter-domain traffic
Do some other validation
◦ Extrapolate estimates with fit from ground-truth data
◦ Talk with operators
13
Where is traffic going?
Increasingly: Google and Comcast
◦ Tier 1 still has large fraction,
but large portion of it is to Google!
◦ Why?
Consolidation of
Over time Google begins
delivering YT’s traffic
As of 2009 Google is 6%
Consolidation of Content (Grouped Origin ASN)
of
traffic
traffic
◦ Fewer ASes responsible
for more of the traffic
Number of Grouped ASN
14
Why is this happening?
Market Forces Intuition
Revenue from
Internet Transit
Source: Dr. Peering, Bill Norton
Revenue from
Internet Advertisement
Source: Interactive Advertising Bureau
Page 12 - Labovitz SIGCOMM 2010
15
Transit is dead! Long live the eyeball!
Commoditization of IP and Hosting / CDN
◦ Drop of price of wholesale transit
◦ Drop of price of video / CDN
◦ Economics and scale drive enterprise to “cloud”
Consolidation
◦ Bigger get bigger (economies of scale)
◦ e.g., Google, Yahoo, MSFT acquisitions
Success of bundling / Higher Value Services – Triple and quad play, etc.
New economic models
◦ Paid content (ESPN 3), paid peering, etc.
◦ Difficult to quantify due to NDA / commercial privacy
Disintermediation
◦ Direct interconnection of content and consumer
◦ Driven by both cost and increasingly performance
16
New applications + ways to access
Fixed vs. Mobile Usage
17
New applications + ways to access
Fixed vs. Mobile Usage
18
The shift from hierarchy to flat
Verizon
$
Tier 1 ISPs
(settlement free peering)
AT&T
$$$
Money follows the arrows.
Sprint
$
$
Tier 2 ISPs
Regional Access
Provider
Regional Access
Provider
$
Local Access
Provider
$
Tier 3 ISPs
$
Local Access
Provider
Autonomous systems (ASes)
connect to each other based on
business relationships.
$
Businesses/consumers
The shift from hierarchy to flat
Verizon
Tier 1 ISPs
(settlement free peering)
AT&T
Sprint
Tier 2 ISPs
Regional Access
Provider
Regional Access
Content Provider
provider no longer
Local Access Provider doesn’t have to pay
for consumer access to content!
Tier 3 ISPs
needs to pay for transit!
More “eyeballs” less $$
Local Access
Provider
$
$
IXP
Local Access
Provider
$
Businesses/consumers
A more accurate model?
A New Internet Model
Settlement Free
Pay for BW
Pay for access BW
Flatter and much more densely interconnected Internet
Disintermediation between content and “eyeball” networks
New commercial models between content, consumer and transit
21
How do ASes connect?
Point of Presence (PoP)
◦ Usually a room or a building (windowless)
◦ One router from one AS is physically connected to the other
◦ Often in big cities
◦ Establishing a new connection at PoPs can be expensive
Internet eXchange Points (IXP)
◦ Facilities dedicated to providing presence and connectivity for
large numbers of ASes
◦ Many fewer IXPs than PoPs
◦ Economies of scale
22
IXPs Definition
Industry definition (according to Euro-IX)
A physical network infrastructure operated by a single
entity with the purpose to facilitate the exchange of
Internet traffic between Autonomous Systems
The number of Autonomous Systems connected should
be at least three and there must be a clear and open
policy for others to join.
https://www.euro-ix.net/what-is-an-ixp
23
IXPs worldwide
https://prefix.pch.net/applications/ixpdir/
24
Inside an IXP
Connection fabric
◦ Can provide illusion of all-to-all
connectivity
◦ Lots of routers and cables
Also a route server
◦ Collects and distributes routes
from participants
25
Structure
IXPs offer connectivity to
ASes enable peering
26
Inside an IXP
Infrastructure of an IXP (DE-CIX)
Robust infrastructure
with redundency
http://www.de-cix.net/about/topology/
27
IXPs – Publicly available information
28
How much traffic is at IXPs?*
We don’t know for sure!
◦ Seems to be a lot, though.
◦ One estimate: 43% of exchanged bytes are not visible to us
◦ Also 70% of peerings are invisible
*Mainly borrowed stolen from Feldmann 2012
29
Revised model 2012+
30