What's inside the cloud?!

(1)

What's inside the cloud ?!

(2)

Initial Arpanet

(3)

Initial Arpanet

Interface Message Processors

- DDP-516 mini-computers - 24 Kbyte of Core memory

- Store-and-forward packet switching - Predecessors of present routers

(4)

Initial Arpanet

Leased Lines

- Modems - 50 Kbps

(5)

Initial Arpanet

Leased Lines

- Modems - 50 Kbps

IBM System/360

SDS Sigma 7 PDP-10

(6)

Initial Arpanet

First link operational

21/11/1969

4 nodes connected

5/12/1969

(7)

Arpanet grows...

December 1969

(8)

...and grows...

June 1970

(9)

... and grows ...

December 1970

(10)

... and grows ...

September 1971

(11)

... and grows ...

1971

(12)

... and grows ...

March 1972

(13)

... and grows ...

September 1973

Sattelite links !

(14)

... and grows!

July 1977

(15)

Logical Arpanet Map

(16)

Internetworking?

●

Many networks being set up:

●

EARN, Bitnet, Janet, Csnet, Eunet, ...

●

and coupled to Arpanet

●

Jan. 1, 1982: Arpanet switches to TCP/IP

(see RFC 801)

●

1986: Creation of NSFNet

●

New high speed backbone

(17)

(18)

NSFNet

●

Grows rapidly:

●

1986: 56 Kbps backbone

●

1988: 1.5 Mbps backbone

–

already connects 170 TCP/IP enabled networks

●

1990: Arpanet dissolves, NSFNet takes over

●

1991: Commercial use of NSFNet accepted

–

many existing commercial networks connected to NSFNet

●

1992: 44.736 Mbps backbone (T3)

(19)

NSFNet traffic for November 1994

0 bytes 1 TB

(20)

Privatising NFSNet

●

NFSNet will migrate to private industry

●

New structure: Network Access Points (NAPs)

–

provide access to high speed links (backbone)

–

commercially operated

–

Initially (1994), 4 155 Mbps NAPs were created by NSF:

● New York (Sprint)

● Washington DC (MFS)

● Chicago (Ameritech)

● California (Pacific Bell)

●

30/04/1995: NFSNet dissolves

–

Internet now is interconnection of different commercially

operated networks

(21)

Internet Service Providers

●

Internet Service Provider (ISP)

●

Provide Internet access to customers

●

Customer connects to ISP Point of Presence (PoP)

●

Different categories or “Tiers”

●

Three ways to connect ISP network to other ISPs

●

Pay other ISP for access = Transit

●

Interconnect networks for free = Peering

●

Other ISP pays you

●

An internet user should be able to contact every

other internet user

(22)

Tier-1 Providers

●

Tier 1 providers don't pay for network access

●

There's no more Internet backbone

●

Many Internet backbones, owned by companies

●

Tier 1 Internet Service Providers

–

have large, high-bandwidth, worldwide networks

–

e.g. AT&T, Sprint, Savvis, Qwest, Level 3, ...

(23)

(24)

telegeography.com

(25)

Point Of Presence

●

Point-of-Presence (PoP):

●

provides access to provider network

●

you have to provide a connection to the PoP to

connect to the Internet through your ISP

●

Note: Private Network Access Point (PNAP)

●

direct private access to provider network

●

<--> PoP, which is shared access point

(26)

Tier-1 Providers

●

Tier 1 Providers interconnect their networks

●

this creates an Internet Backbone

●

Tier 1 Providers = Backbone Providers

●

Typically don't charge each other for traffic

–

connecting networks is win-win situation, both providers get

faster access to the other one's network and more reliable

and possibly faster access to the Internet

–

= Peering

(27)

Peering

●

Exchanging network traffic with peers is called

peering.

●

physical connection between networkd

–

physically co-locate PoP of both providers and connect them

●

setting in both networks for route exchange

●

agreement on amount and type of traffic

●

Also known as Settlement Free Interconnection

●

ISP has Peering Policy stating conditions for

peering (open,

(28)

Tier-2 providers

●

Users don't connect directly to a tier-1 provider

●

Tier-2 providers connect their network to one or

more tier-1 providers and offer PoP's for their

users

●

T2 provider has to pay T1 provider

–

=/= peering !

(29)

Internet Food Chain

Tier1 Tier1 Tier1

Tier2 Tier2 Tier2 Tier2 Tier2 Tier2

backbone

PoP PoP PoP PoP PoP

PoP PoP PoP

(30)

Internet Food Chain

●

But, it isn't that simple...

●

Tier-2 providers will also start connecting their

networks --> Peering

–

don't have to pay, win-win situation

● Less traffic to Tier-1 providers, so less costs for Tier-2 provider

● Less traffic to Tier-1 providers, so backbone less busy

● Faster access to systems in peer networks

●

Peering often happens in an Internet Exchange (IX)

(31)

Internet Food Chain

Tier1 Tier1 Tier1

Tier2 Tier2 Tier2 Tier2 Tier2 Tier2

backbone

PoP PoP PoP PoP PoP

PoP PoP PoP

IX IX

Tier3

(32)

Internet eXchange

Tier1 Tier1

Tier2

Tier2 Tier2

Tier2

PoP PoP

IX

(33)

Internet eXchange

●

Internet eXchange (IX)

●

Belgium: BNIX (www.bnix.be)

●

Netherlands: AMS-IX (www.ams-ix.net)

●

UK: LINX (www.linx.net)

●

... (www.dix.dk/euro/)

●

Typically upto 10GBit switching

●

Note, IX can provide connections between

providers at different Tiers

●

It's just a (number of) datacenter(s) ...

●

It's a collection of PoP's of different providers

(34)

LINX

●

London INternet eXchange is distributed over 6

locations:

(35)

Belgian National Internet eXchange

●

http://www.bnix.be

●

www.bnix.be/stats.php

●

www.bnix.be/members.php

●

(36)

Who's peering?

●

Have a look at:

●

www.peeringdb.com

●

www.robtex.com

(37)

Overview

(38)

But who's the boss?

(39)

ISOC

●

ISOC = Internet Society (www.isoc.org)

●

The Internet Society (ISOC) is a nonprofit

organisation founded in 1992 to provide

leadership in Internet related standards,

education, and policy.

●

Steers IETF, IAB, ICANN, ...

●

Works with governments about policy

(40)

ICANN

●

ICANN = Internet Corporation for Assigned

Names and Numbers (www.icann.org)

●

Responsible for IP addresses, Top-Level Domains

(TLDs), domain names

●

Most of technical work done as IANA

(41)

IANA

●

IANA = Internet Assigned Numbers Authority

●

part of ICANN

●

delegates IP allocation Regional Internet Registries

(RIRs)

●

www.iana.org

●

DNS Root Zones (ccTLDs and gTLDs)

●

IP Addresses

●

AS Numbers

●

Protocol numbers, eg. port numbers

(42)

Regional Internet Registries (RIRs)

●

Manage and allocate IP addresses for IANA

● RIPE NCC (www.ripe.net)

– Réseaux IP Européen Network Control Centre

● ARIN (www.arin.net)

– American Registry for Internet Numbers

● APNIC (www.apnic.net)

– Asia Pacific Network Information Centre

● LACNIC (www.lacnic.net)

– Latin America and Carribean Internet Address Registry

● AfriNIC (www.afrinic.net)

– African Network Information Centre

from www.apnic.net

(43)

IP Address Space

●

Originally allocated in

classes (A,B,C)

●

Now CIDR

●

Running out of

addresses?

●

We'll talk about Ipv6

later

From www.xkcd.com

(44)

Need IP addresses?

●

>= 2048 addresses? (/21 or larger)

●

Become a member of RIPE NCC

–

IP Addresses are free, but you pay for the services of the

RIR...

●

< 2048 addresses

●

Ask a member of the RIR

–

Most often an ISP

(45)

Example: KHLeuven

●

KHLeuven has 193.190.138.0/24

●

IANA allocated 193.0.0.0/8 to RIPE NCC

–

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

space/ipv4-address-space.txt

●

whois 193.190.138.0

●

RIPE NCC allocated 193.190.0.0/15 to Belnet

●

Belnet allocated 193.190.138.0/24 to KHLeuven

(46)

Border Gateway Protocol (BGP)

●

BGP = De facto standard for inter-domain routing

●

Autonomous System (AS) = collection of IP networks

and the interconnecting routers that present a

common routing policy to the Internet (see RFC 1930)

–

identified by AS-number, assigned by IANA

● number between 1 and 65535 (16 bits)

●

Runs on TCP, port 179

–

TCP connections between routers are kept alive

●

Defined in RFC 1771

(47)

BGP

●

Path Vector algorithm using AS instead of

individual routers

(48)

BGP

●

Path Vector algorithm using AS instead of

individual routers

●

hide network layout of AS

–

routing inside AS organized by some internal gateway

protocol

–

BGP has to rely on AS/IGP to prevent internal loops

(49)

BGP Peers

●

BGP Peers or Neighbours

●

manual configuration

–

manually add neighbours to the router config

●

On connection establishment: full routing information

exchanged

●

After this, only changes are transmitted

(50)

BGP: Routing Table Size

●

Active BGP entries in Global Routing Table:

http://bgp.potaroo.net

(51)

BGP: Routing Table Size

●

Increasing Routing Table Size increases workload

and memory demands on routers

●

Countermeasure:

–

Classless Inter-Domain Routing (CIDR)

and Route aggregation

–

Instead of advertising 256 Class C address blocks, e.g.

195.100.1.0, 195.100.2.0, ..., an ISP can now advertise

195.100.0.0/16

● also called supernetting

(52)

BGP in action

●

Looking Glass web interfaces available to inspect

BGP: http://www.nanog.org/lookingglass.html

●

BGPlay: http://bgplay.routeviews.org/bgplay/

●

(53)

Traceroute

●

Traceroute shows route packets follow

●

Linux/Unix: traceroute

●

Windows: tracert

●

Web based traceroute:

–

many listed at http://www.traceroute.org/

●

Different GUI's available

(54)

Traceroute: example

gerben@rgmgedie:/tmp$ traceroute www.mit.edu

traceroute to www.mit.edu (18.7.22.83), 30 hops max, 38 byte packets

1 192.168.123.254 (192.168.123.254) 0.311 ms

2 10.75.128.1 (10.75.128.1) 11.435 ms

3 dD5E0FAC2.access.telenet.be (213.224.250.194) 10.203 ms 4 IBGENT02SRP50.telenetops.be (213.224.126.6) 14.855 ms 5 213.224.126.110 (213.224.126.110) 17.105 ms

6 212.3.237.1 (212.3.237.1) 15.795 ms

7 so510.mp2.Brussels1.Level3.net (4.68.113.209) 13.524 ms 8 so300.mp1.Boston1.Level3.net (209.247.9.125) 101.530 ms 9 ae2254.car2.Boston1.Level3.net (4.68.100.99) 94.844 ms 10 4.79.2.2 (4.79.2.2) 92.545 ms 100.322 ms 92.759 ms 11 W92RTR1BACKBONE.MIT.EDU (18.168.0.25) 97.502 ms

12 WWW.MIT.EDU (18.7.22.83) 93.833 ms

(simplified output)

(55)

Traceroute: example

1 192.168.123.254 (192.168.123.254) 0.311 ms

2 10.75.128.1 (10.75.128.1) 11.435 ms

6 212.3.237.1 (212.3.237.1) 15.795 ms

12 WWW.MIT.EDU (18.7.22.83) 93.833 ms

(simplified output) 12 Hops on route

(56)

Traceroute: example

1 192.168.123.254 (192.168.123.254) 0.311 ms

2 10.75.128.1 (10.75.128.1) 11.435 ms

6 212.3.237.1 (212.3.237.1) 15.795 ms

12 WWW.MIT.EDU (18.7.22.83) 93.833 ms

(simplified output) One line for each router on the route

(Would normally contain results for 3 packets)

(57)

Traceroute: example

1 192.168.123.254 (192.168.123.254) 0.311 ms

2 10.75.128.1 (10.75.128.1) 11.435 ms

6 212.3.237.1 (212.3.237.1) 15.795 ms

12 WWW.MIT.EDU (18.7.22.83) 93.833 ms

(simplified output) Host name and IP for router

(if reverse lookup possible)

(58)

Traceroute: example

1 192.168.123.254 (192.168.123.254) 0.311 ms

2 10.75.128.1 (10.75.128.1) 11.435 ms

6 212.3.237.1 (212.3.237.1) 15.795 ms

12 WWW.MIT.EDU (18.7.22.83) 93.833 ms

(simplified output) Round Trip Time between local system and this router in milliseconds

(normally 3 different RTTs)

(59)

Traceroute: use

●

What can we learn from a traceroute?

●

Detect problems:

–

locate route interruption

–

bad router configuration

–

inefficient routing

–

high latency hops

●

Provide information about network structure

(60)

Traceroute: implementation

●

How does traceroute report the route?

●

Let's see what happens by capturing the packets

–

use ethereal Wireshark or tcpdump or ...

(61)

Traceroute: implementation

●

What do we see:

●

DNS query and response for www.mit.edu

●

UDP packet from local to www.mit.edu

–

Source port = 61538 en Dest port = 33435

–

Doesn't provide any information on route...

–

But Time To Live (TTL) value in IP header = 1

–

First router decreases TTL, and discards packet

● Sends ICMP TTL Exceeded message

● Local system now knows IP address of first router (source address of ICMP packet)

●

DNS reverse lookup for first router

●

UDP packet from local to www.mit.edu

–

TTL = 2

(62)

Traceroute: implementation

●

Traceroute algorithm:

●

Send UDP packet to high port number on target

system with TTL = 1, 2, 3, ...

●

Receive ICMP TTL exceeded message from 1st, 2nd,

3rd, ... router

●

When target host reached (TTL = route length):

–

selected UDP port not in use: receive ICMP port

unreachable message

–

selected UDP port in use: no answer...

(63)

Traceroute: GUI examples

xtraceroute VisualRoute