Topic 1: Internet Architecture & Addressing

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Topic

1: Internet Architecture & Addressing

Objectives

Understand the general architecture of Internet

Identify the main actors in the Internet architecture Identify the main actors in the Internet architecture

Identify the main organizations implied in Internet

Understand IPv4 address depletion problem

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Topic

1: Internet Architecture & Addressing

Internet Architecture: ISP's, corporate networks and access networks.

Organizations that manage the operation of

businesses on the Internet: RIR (Regional Internet businesses on the Internet: RIR (Regional Internet

Registers), LIR (Local Internet Registries). Internet Addressing: IPv4 depletion and IPv6. Exchange Points.

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Topic 1: Internet Architecture & Addressing

Internet: global system of interconnected computer networks that use the standard TCP/IP suite protocol to connect users and applications.

Users are inter-connected through ISP (Internet

Service Provider)

Internet Service Provider (ISP)

Provides connectivity and services to end users (Dial-up), corporative networks (IP-Net Clients) and other ISPs

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Internet Service Provider

End users (Dial-clients):

Contract an access line (i.e., modem, ADLS, …). The ISP may be a telecom

operator or has sub-contracts with telecom operators to offer service connectivity

Corporative Networks (IP-Net-client)

Local Area Networks (LANs)

Contract switched/dedicated lines for linking their sites forming a VPN Contract switched/dedicated lines for linking their sites forming a VPN

Contract one or several lines (backup, redundancy, load balancing, …) to the

ISP

Peering between ISPs: ISPs act with con client-to-provider, peer-to-peer

and provider-to-client relationships

ISPs connections may be private (using Telecom operator lines) or public

(“Exchange points”)

Retail services (directly to customers) versus Wholesail services (in large

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Internet Architecture

ISP ISP ISP ISP ISP Internet Providers Dial-up clients IP-Net clients IP-Net clients IP-Net clients IP-Net clients WAN WAN WAN WAN Access Technologies Users

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IANA



The Internet Assigned Numbers Authority

(IANA) is the body responsible for coordinating

some of the key elements that keep the

Internet running smoothly. Whilst the Internet

is renowned for being a worldwide network

free from central coordination, there is a

technical need for some key parts of the

Internet to be globally coordinated – and this

coordination role is undertaken by IANA.

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IANA Activities

 Domain Names

IANA manages the DNS root, the .int and .arpa domains, and an IDN practices resource.

 Number Resources

IANA coordinates the global pool of IP and AS numbers, providing them to Regional Internet Registries.

 Protocol Assignments

Internet protocols’ numbering systems are managed by IANA in conjunction with standards bodies.

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Domain Names

 _{country code top-level domains} _{(ccTLD): Used by a}_country _or

a dependent territory. It is two letters long, for example .us for the

United States. With some historical exceptions, the code for any territory is the same as its two-letter ISO 3166 code.

 generic top-level domains (gTLD): Used by a particular class of

organizations (for example, .com for commercial organizations). It is three or more letters long. Most gTLDs are available for use worldwide, but for historical reasons .mil (military) and .gov

(governmental) are restricted to use by the respective U.S. authorities. gTLDs are sub classified into sponsored top-level domains (sTLD), e.g. .aero, .coop and .museum, and

unsponsored top-level domains (uTLD), e.g. .biz, .info, and .name.

 infrastructure top-level domains (iTLD): The top-level domain .arpa .int, .root.

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Internet Numbers (addresses)

 Users are assigned IP addresses by Internet service

providers (ISPs). ISPs obtain allocations of IP addresses from a local Internet registry (LIR) or national Internet registry (NIR), or from their

appropriate Regional Internet Registry (RIR)



IPv4:

http://www.iana.org/assignments/ipv4-address-space

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Protocol Numbers

 IANA is responsible for maintaining many of the codes

and numbers contained in a variety of Internet

protocols, enumerated below. We provide this service in coordination with the Internet Engineering Task

Force (IETF).

 Address Family Numbers

 Address Resolution Protocol (ARP) Parameters

 Autonomous System (AS) Numbers

 http://www.iana.org/protocols/

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IANA organization

 Regional Internet Registry (RIR)  National Internet registry (NIR)  Local Internet registry (LIR)

 RIR

 AfriNIC Africa Region

 APNIC Asia/Pacific Region

 ARIN North America Region

 LACNIC Latin America and some Caribbean Islands

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Regional Internet Registries (RIRs):

Independent organizations that supports Internet resources coordination in a geographical region and develop consistent policies and promote best current practice for the Internet.

Each RIR manage:

IPv4 and IPv6 Address blocks and AS number assignments

DO NOT manage Name Domains (done by ICANN: Internet

Corporation for Assigned Names and Numbers ) There are 5 Regions

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Topic 1: Internet Architecture & Addressing Regional Internet Registries (RIRs):

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Topic 1: Internet Architecture & Addressing Regional Internet Registries (RIRs):

LIR (Local Internet Registry) Members of RIR

NIR (National Internet Registry) coordinate IP allocations at national level. There are no NIR in Europe, but APNIC and LACNIC have them. RIRs allocate IP address space and AS Numbers to Local Internet

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RIPE NCC (http://www.ripe.net/)

Provides Internet resource allocations, registration services and coordination activities that support the operation of the Internet globally.

Internet Governance: based on a commitment to enhance

the cooperation between the public and private sectors

LIR (Local Internet Register) Services: members of a RIR

LIR (Local Internet Register) Services: members of a RIR Data & Tools: provides databases and monitoring tools that

support stable, reliable and secure Internet operations.

RIPE Database support: contains registration details of IP

addresses and AS Numbers originally allocated by the RIPE NCC

Operates 1 of the 13 K-root Name Servers

Provides high-quality measurements and analysis that can be

used for a variety of operational, media, governmental and law enforcement activities.

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Criteria to obtain an AS number

Only when the routing policy is different from your ISP provider routing policy (RFC 1930)

That implies that the customer has to be connected to at least two

ISP (multi-homing) with different routing policies ¿What is a LIR (Local Internet Registry) ?

Any member of a RIR is a LIR

Typically ISP, Telecom Operators and Corporative Networks

(Enterprise)

Obligatory if you need IPv4 blocks higher or equal to /21 IPv4

blocks

If you need lower blocks contact an ISP

See http://www.ripe.net/membership/maps/ in

order to see ISP and LIR in any geographical zone covered by RIPE

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Topic 1: Internet Architecture & Addressing AS numbers in Internet

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Autonomous Systems (AS) or Routing Domain: is a group of IP networks run by one or more network operators with a single, clearly defined routing policy.

AS are identified with 16 bits (65535 AS’s)

AS’s exchange routes (IP subnets) using Inter-domain Routing Protocols such as BGPv4

Internally, AS’s exchange routes (IP subnets) using Intra-domain

Routing Protocols such as OSPF, IS-IS, EIGRP, … Routing Protocols such as OSPF, IS-IS, EIGRP, …

AS₁ AS2 AS₃ EGP IGP IGP IGP

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Internet Service Provider (ISP) and Autonomous

Systems (AS):

An ISP is an administrative entity that may have one or more AS numbers assigned depending of its architecture and geographical situation

In general an AS number may be assigned to an ISP or to a Corporative Network,

Thus, not all AS are ISP, however all ISPs have one or more AS number assigned

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Autonomous Systems

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AS relationships



The relationships between these networks are

generally described by one of the following

three categories:

 Transit - You pay money (or settlement) to another network for Internet access (or transit).

 Peer (or swap) - Two networks exchange traffic between each other's customers freely, and for mutual benefit.

 Customer (or sell) - Another network pays you money to provide them with Internet access.

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Hierarchical Organization



Tier 1 - A network that can reach every other

network on the Internet without purchasing IP

transit.



Tier 2 - A network that peers with some

networks, but still purchases IP transit to reach

at least some portion of the Internet.



Tier 3 - A network that solely purchases transit

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MIRI: Computer Networks

Master in Innovation and Research in Informatics

Default Free Zone

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Default Free Zone

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ISP peering

Private peering

Point-to-point connections among two AS in order to

transport routes and traffic

Increase link reliability and offer high bandwidth but at cost

increases

Alleviate the traffic that crosses public exchange points

Connections are bi-laterally negotiated among the ISP

(peer-to-peer basis)

Routing and business treats are confidential and only known

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ISP peering

Public peering

National: inter-connect ISP belonging to the same country

Espanix (www.espanix.net) with 45 partners and 96

averaged Gb/s of traffic, Catnix (www.catnix.net) with 24 averaged Gb/s of traffic, Catnix (www.catnix.net) with 24 partners and approx 700 switched Mb/s, EuskoNix with 7 partners and 100 Mb/s

International: inter-connect National IXP; EuroIX (www.euro-ix.net) with 105 European IXP

The inter-connectivity matrix between IXP will give us

information about ISP peering

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Motivations for peering

 Increased capacity for extremely large amounts of

traffic (distributing traffic across many networks).

 Increased control over your traffic (reducing

dependence on one or more transit providers).

 Improved performance (attempting to bypass potential

bottlenecks with a "direct" path).

 Improved perception of your network (being able to

claim a "higher tier").

 Government regulations, or the desire to avoid the

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Exchange Points

 An Internet exchange point (IX or IXP) is a physical

infrastructure that allows different Internet service providers (ISPs) to exchange traffic between their

networks (autonomous systems) by means of mutual peering agreements, which allow traffic to be

exchanged without cost.

 European Internet Exchange Association

 http://www.euro-ix.net/

 Espanix (punto neutro español)

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Internet Exchange Point



Requirements for an ISP to be member:

 One BGP router, at least,  AS number

 With IPv4 and IPv6

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Topic 1: Internet Architecture & Addressing Espanix (daily and weekly traffic)

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Topic 1: Internet Architecture & Addressing Catnix:

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Tiers:

Tier 1 ISPs (troncales) are large and together hold all the world’s Internet routes, and peer with each other to give each other access to all Internet routes.

Tier 2 ISPs buy connectivity (upstream transit) to the world Internet routes from one or more tier 1 ISPs, and hence their IP network(s) becomes a sub-set of those tier 1’s IP networks. Tier 2 ISPs will also

peer with each other to minimize the amount of traffic to and from the peer with each other to minimize the amount of traffic to and from the

tier 1 ISPs from whom they buy upstream transit.

Tier 3 ISPs buy upstream transit from Tier 2 ISPs and so on, however the model becomes increasingly vague, since an ISP may buy upstream transit from both a tier 1 ISP and a tier 2 ISP, and may peer with tier 2 and tier 3 ISP’s and occasionally a tier 1 ISP, and so on. The term is really only of use to differentiate between tier1 ISPs who do not need to buy upstream transit due to their peerings with other tier 1 ISPs, and the rest of the ISPs, tier 2 and below.

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The Cooperative Association for Internet Data Analysis

(CAIDA): http://www.caida.org/home/

Provides statistics about AS organization, size, peering, etc

E.g. AS rank by customer cone (number of AS’s or IPv4

addresses ) reachable via customers or customers of customers of an AS (http://as-rank.caida.org/)

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Internet 1995-2007

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Arbor Networks. ATLAS Internet Observatory. 2009 Annual Report. NANOG47

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Internet Service Provider

ISP offer different types of services

Dedicated Internet Access services

T1/E1 lines (1.5, 2 Mbps), T3/E3 (45, 34 Mbps), OC3 (155 Mbps),

OC12 (622 Mbps), OC48 (2.5 Gbps), etc

Switched Internet Access services

FR (Frame Relay) or ATM FR (Frame Relay) or ATM

Other Internet Access services

Modems, ADSL, RDSI (BRI, PRI), etc

Hosting/housing Services and CPD services

Racks, servers (e.g.; Web), equipment, etc

End user services

VPNs, e-mail, news, Web, IP multicast, etc

Content Provider services (Content Distribution Networks such

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SLA (Service Level Agreement): agreement that guarantees

the contract offered by an ISP and that penalize the ISP if this one does not comply the contract

Availability level (% of time that the customer agrees in losing

connectivity) measured as the number of delivered packets respect to the transmitted

Bandwidth contracted (Mb/s)

Throughput (Mb/s) in high availability (rushy hours)

Response time against connectivity failures (e.g. 24/7 service), Response time against connectivity failures (e.g. 24/7 service),

penalize with respect the amount of time without connectivity

Redundancy (multi-homing) Security

Monitoring services

Quality of Service (QoS): service levels (e.g. Gold, Silver, …)

Packet marking, dropping, end-to-end delays, ….

El SLA is a customer support service

http://www.ndo.com/service-level-agreement.html http://www.localisp.com/Company/Policies/SLA-T1.pdf

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Corporative Networks or IP-Net Client

Companies with

end users

and

end services

As any end user, they are connected to other end users and other corporative networks via an ISP

A corporative network can be something ranging

between: between:

Small company with few users, to a large company with thousands

of users

A corporative network may:

Manage their services in a CPD (Centre Processing Data) located in

the Main Site

Manage their services via others (e.g. either another corporative

network or an ISP) that provides the service (e.g. hosting, housing, virtualization, …)

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Corporative Networks or IP-Net Client

WAN BLOCK SERVER BLOCK

BACKBONE

* “Internetwork Design Guide”, CISCO documentation

CORE BLOCK

SWITCH BLOCK SWITCH BLOCK SWITCH BLOCK

DISTRIBUTED LAYER

ACCESS LAYER