Introduction to The
Internet
IPv6 Transition Strategies and
Technologies Workshop
5th – 6th August 2014
Vientiane
Last updated 13 June 2014
1
Preamble
p  Course
slides:
http://www.itu.int/en/ITU-D/RegionalPresence/AsiaPacific/Pages/Events/2014/
August%20Laos/IPv6-Transition-Strategiesand-Technologies-Workshop.aspx
n  Please ask questions any time
n  This is an interactive workshop
n
2
Introduction to the Internet
p  Topologies
and Definitions
p  IP Addressing
p  Internet Hierarchy
p  Gluing it all together
3
Topologies and
Definitions
What does all the jargon mean?
4
Some Icons…
Router
(layer 3, IP datagram forwarding)
Ethernet switch
(layer 2, packet forwarding)
Network Cloud
5
Routed Backbone
p
ISPs build networks
covering regions
n
n
p
p
p
p
Regions can cover a
country, sub-continent, or
even global
Each region has points of
presence built by the ISP
Routers are the
infrastructure
Physical circuits run
between routers
Easy routing configuration,
operation and
troubleshooting
The dominant topology
used in the Internet today
6
MPLS Backbones
p
p
Some ISPs & Telcos use
Multi Protocol Label
Switching (MPLS)
MPLS is built on top of
router infrastructure
n
n
p
Replaces old ATM
technology
Tunnelling over IP network
Main purpose is to provide
VPN services
n
Although these can be
implemented with other
tunnelling technologies
such as GRE
7
Points of Presence
p  PoP
– Point of Presence
Physical location of ISP’s equipment
n  Sometimes called a “node”
n
p  vPoP
– virtual PoP
To the end user, it looks like an ISP location
n  In reality a back hauled access point
n  Used mainly for consumer access networks
n
p  Hub/SuperPoP
n
– large central PoP
Links to many PoPs
8
PoP Topologies
p
Core routers
n
p
Distribution routers
n
p
connections to other providers
Service routers
n
p
high port density, connecting the end users to the
network
Border routers
n
p
higher port density, aggregating network edge to the
network core
Access routers
n
p
high speed trunk connections
hosting and servers
Some functions might be handled by a single
router
9
Typical PoP Design
Other ISPs
Other ISPs
Border
Backbone link
to another PoP
Backbone link
to another PoP
Network
Core
Service
Network
Operation
Centre
Access
Business
Customer
Aggregation
Service
ISP Services
(DNS, Mail, News,
FTP, WWW)
Access
Hosted Services
Consumer
Aggregation
10
More Definitions
p  Transit
Carrying traffic across a network
n  Usually for a fee
n
p  Peering
Exchanging routing information and traffic
n  Usually for no fee
n  Sometimes called settlement free peering
n
p  Default
n
Where to send traffic when there is no
explicit match in the routing table
11
Peering and Transit example
transit
provider A
peering
IXP-West
provider B
provider E
Backbone
Provider C
peering
peering
IXP-East
Backbone
Provider D
provider F
transit
A and B peer for free, but need
transit arrangements with C and D
to get packets to/from E and F
12
Private Interconnect
Autonomous System 334
Provider D
border
border
Provider C
Autonomous System 99
13
Public Interconnect
p  A
location or facility where several ISPs
are present and connect to each other
over a common shared media
p  Why?
n
To save money, reduce latency, improve
performance
p  IXP
– Internet eXchange Point
p  NAP – Network Access Point
14
Public Interconnect
p  Centralised
(in one facility)
p  Distributed (connected via WAN links)
p  Switched interconnect
Ethernet (Layer 2)
n  Technologies such as SRP, FDDI, ATM, Frame
Relay, SMDS and even routers have been used
in the past
n
p  Each
provider establishes peering
relationship with other providers at IXP
n
ISP border router peers with all other provider
border routers
15
Public Interconnect
ISP 1
ISP 2
ISP 3
ISP 4
IXP
ISP 5
ISP 6
Each of these represents a border router in a different autonomous system
16
ISPs participating in Internet
p  Bringing
all pieces together, ISPs:
Build multiple PoPs in a distributed network
n  Build redundant backbones
n  Have redundant external connectivity
n  Obtain transit from upstream providers
n  Get free peering from local providers at IXPs
n
17
Example ISP Backbone Design
ISP Peer
ISP Peer
IXP
ISP Peer
ISP Peer
Upstream1
Upstream 2
Upstream 2
PoP 2
Upstream1
PoP 1
Network
Core
Backbone
Links
PoP 3
PoP 4
18
IP Addressing
Where to get address space and
who from
19
IP Addressing Basics
p  Internet
uses two types of addressing:
IPv6 – the new IP protocol
n  IPv4 – legacy IP protocol
n
p  Internet
n
uses classless routing
Routers must be CIDR capable
p
Classless InterDomain Routing
No routing assumptions made based on the
address block
n  Engineers talk in terms of prefix length
n  For example: 158.43/16 and 2001:db8::/32
n
20
History of IP Addressing
p
Pre-CIDR (before 1994)
n
n
n
p
The CIDR IPv4 years (1994 to 2010)
n
p
Big networks got a class A
Medium networks got a class B
Small networks got a class C
Sizes of IPv4 allocations/assignments made according to
demonstrated need – CLASSLESS
IPv6 adoption (from 2011)
n
n
n
Network Operators get at least one /32
End Sites get /48
IANA’s free pool is depleted (February 2011) – the size
of IPv4 address allocations and assignments is now very
limited
21
IP Addressing
p
IP Address space is a resource shared amongst
all Internet users
n
n
n
n
p
Regional Internet Registries delegated allocation
responsibility by the Internet Assigned Numbers
Authority (IANA)
AfriNIC, APNIC, ARIN, LACNIC & RIPE NCC are the five
RIRs
RIRs allocate address space to ISPs and Local Internet
Registries
ISPs/LIRs assign address space to end customers or
other ISPs
RIRs address distribution:
n
n
IPv6 is plentiful
IPv4 is very limited
22
Address delegation hierarchy
IANA
AfriNIC
APNIC
ARIN
LACNIC
(Africa)
(Asia & Pacific)
(N America)
ISPs
ISPs
ISPs
ISPs
ISPs
End Users
End Users
End Users
End Users
End Users
(C&S America)
RIPE NCC
(EU,ME,C Asia)
23
Non-portable Address Space
p  “Provider
Aggregatable” or “PA Space”
Customer uses RIR member’s address space
while connected to Internet
n  Customer has to renumber to change ISP
n  Aids control of size of Internet routing table
n  Need to fragment provider block when
multihoming
n
p  PA
n
space is allocated to the RIR member
All assignments made by the RIR member to
end sites are announced as an aggregate to
the rest of the Internet
24
Portable Address Space
p  “Provider
Independent” or “PI Space”
Customer gets or has address space
independent of ISP
n  Customer keeps addresses when changing ISP
n  Is very bad for size of Internet routing table
n  Is very bad for scalability of the routing system
n  → PI space is rarely distributed by the RIRs
n
25
Internet Hierarchy
The pecking order
26
Global Internet: High Level View
Global Providers
Regional
Provider 1
Regional
Provider 2
Content
Provider 1
Content
Provider 2
Access
R4 1
Provider
Access
Provider 2
IXP
Customer Networks
27
Detailed View of the Global Internet
p
Global Transit Providers
n
n
p
Regional Transit Providers
n
n
n
p
Connect to each other
Provide connectivity to Content Providers
Provide connectivity to Access Providers
Content Providers
n
n
p
Connect to each other
Provide connectivity to Regional Transit Providers
Cross-connect to Access Providers
Peer at IXPs (free traffic to Access Providers)
Access Providers
n
n
Connect to each other across IXPs (free peering)
Provide access to the end user
28
Categorising ISPs
Tier 1 ISP
$
$
$
$
$
$
$
$
Regional ISP
$
$
$
$
Access ISP
$
$
$
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
Regional ISP
Regional ISP
Regional ISP
IXP
IXP
Access ISP
Access ISP
Access ISP
Access ISP
Access ISP
29
Categorising ISPs
p
Tier-1 ISP – definition:
n
n
A provider which peers with other Tier-1s and does NOT
pay for transit
Caveat:
p
p
Regional providers often have the reach of
Tier-1s but still have to rely on maybe one or two
Tier-1s to access the whole Internet
n
p
Many marketing departments call their ISP a Tier-1 – even
though that ISP may still pay for transit to some parts of
the Internet
They often provide access too, via in country domestic
access networks
Access providers work exclusively in their locale
30
Inter-provider relationships
p  Peering
between equivalent sizes of
service providers (e.g. Regional to
Regional)
Shared cost private interconnection, equal
traffic flows
n  No cost peering
n
p  Peering
n
If convenient, of mutual benefit, technically
feasible
p  Fee
n
across exchange points
based peering
Unequal traffic flows, “market position”
31
Default Free Zone
The default free zone is made
up of Internet routers which
have explicit routing
information about the rest of
the Internet, and therefore do
not need to use a default route
NB: is not related to where an
ISP is in the hierarchy
32
Gluing it together
33
Gluing it together
p
Who runs the Internet?
n
n
p
How does it keep working?
n
p
No one
(Definitely not ICANN, nor the RIRs, nor the US,…)
Inter-provider business relationships and the need for
customer reachability ensures that the Internet by and
large functions for the common good
Any facilities to help keep it working?
n
n
Not really. But…
Engineers keep working together!
34
Engineers keep talking to each
other...
p
North America
n
n
n
p
Latin America
n
n
n
p
NANOG (North American Network Operators Group)
NANOG meetings and mailing list
www.nanog.org
Foro de Redes
NAPLA
LACNOG – supported by LACNIC
Middle East
n
n
MENOG (Middle East Network Operators Group)
www.menog.net
35
Engineers keep talking to each
other...
p  Asia
n
APRICOT annual conference
p
n
& Pacific
www.apricot.net
APOPS & APNIC-TALK mailing lists
mailman.apnic.net/mailman/listinfo/apops
p  mailman.apnic.net/mailman/listinfo/apnic-talk
p
n
PacNOG (Pacific NOG)
p
n
mailman.apnic.net/mailman/listinfo/pacnog
SANOG (South Asia NOG)
p
E-mail to sanog-request@sanog.org
36
Engineers keep talking to each
other...
p
Europe
n
n
p
Africa
n
p
p
AfNOG meetings and mailing list
Caribbean
n
p
RIPE meetings, working groups and mailing lists
e.g. Routing WG: www.ripe.net/mailman/listinfo/
routing-wg
CaribNOG meetings and mailing list
And many in-country ISP associations and NOGs
IETF meetings and mailing lists
n
www.ietf.org
37
Summary
p  Topologies
and Definitions
p  IP Addressing
n
PA versus PI address space
p  Internet
Hierarchy
Local, Regional, Global Transit Providers
n  IXPs
n
p  Gluing
n
it all together
Engineers cooperate, common business
interests
38
Introduction to The
Internet
IPv6 Transition Strategies and
Technologies Workshop
5th – 6th August 2014
Vientiane
39