1© 2001, Cisco Systems, Inc. All rights reserved.

Session NumberPresentation_ID

Structure of the Internet

Fred Baker

222© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Today’s Internet

• The optical internet backbone

Gigabit to terabit links

U N I V E R S I T YU N I V E R S I T Y

• Access networksxDSL, cable modem, ISDN, asynchronous dial

20,000 instantaneous sessions per GBPS backbone bandwidth

Campus Networks (LANs)UoSAT-12

Internetin Airlines

333© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Nearby Traceroute

traceroute to www.LB-A.stanford.edu (171.64.14.238), 30 hops max, 40 byte packets 1  sjcm-dc-gw1.cisco.com (171.69.25.2)  0.86 ms  0.49 ms  0.54 ms 2  sjce-sbb1-gw1.cisco.com (171.69.14.113)  0.54 ms  0.48 ms  0.35 ms 3  sjck-rbb-gw2.cisco.com (171.69.14.45)  0.39 ms  0.39 ms  0.48 ms 4  sj-wall-1.cisco.com (171.69.7.182)  0.59 ms  0.35 ms  0.51 ms 5  sjce-dirty-gw1.cisco.com (128.107.240.197)  2.01 ms  0.74 ms  0.66 ms 6  barrnet-gw.cisco.com (128.107.239.54)  1.88 ms  0.67 ms  0.60 ms

 7  p3-3.paloalto-cr2.bbnplanet.net (4.0.26.13)  3.13 ms  1.74 ms  1.48 ms 8  p1-0-0.paloalto-cr9.bbnplanet.net (4.0.2.214)  2.94 ms  1.73 ms  2.94 ms 9  f0-0.paloalto-cr13.bbnplanet.net (131.119.4.22)  5.07 ms  2.22 ms  1.86 ms

10  sunet-gateway.stanford.edu (198.31.10.1)  7.36 ms  4.42 ms  1.81 ms

444© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Nearby Traceroute

traceroute to arachne.berkeley.edu (169.229.131.109), 30 hops max, 40 byte packets 1  sjcm-dc-gw1.cisco.com (171.69.25.2)  0.85 ms  0.57 ms  0.60 ms 2  sjce-sbb1-gw1.cisco.com (171.69.14.113)  0.50 ms  0.38 ms  0.40 ms 3  sjce-rbb-gw1.cisco.com (171.69.14.33)  0.56 ms  0.42 ms  0.44 ms 4  sj-wall-1.cisco.com (171.69.7.170)  0.46 ms  0.47 ms  0.37 ms 5  sjce-dirty-gw1.cisco.com (128.107.240.197)  0.69 ms  0.86 ms  1.11 ms 6  barrnet-gw.cisco.com (128.107.239.54)  0.63 ms  2.33 ms  0.60 ms

 7  p3-3.paloalto-cr2.bbnplanet.net (4.0.26.13)  2.04 ms  1.39 ms  1.36 ms 8  p7-1.paloalto-nbr2.bbnplanet.net (4.0.6.77)  1.53 ms  1.53 ms  1.43 ms 9  p1-0.paix-bi1.bbnplanet.net (4.0.6.102)  1.76 ms  1.84 ms  2.19 ms10  p0-0.xpaix21-qwest.bbnplanet.net (4.2.49.14)  1.94 ms  1.77 ms  1.83 ms11  205.171.205.29 (205.171.205.29)  3.24 ms  3.80 ms  3.50 ms12  205.171.14.98 (205.171.14.98)  3.91 ms  3.34 ms  2.70 ms13  65.113.32.210 (65.113.32.210)  4.14 ms  2.61 ms  3.02 ms

14  QSV-M10-C2.GE.calren2.net (137.164.12.166)  4.40 ms  2.76 ms  2.55 ms15  atm1-1-0dot1.inr-new-666-doecev.Berkeley.EDU (128.32.0.69)  7.08 ms  6.25 ms  5.70 ms16  vlan196.inr-202-doecev.Berkeley.EDU (128.32.0.75)  9.39 ms  10.38 ms  8.58 ms17  vlan210.inr-203-eva.Berkeley.EDU (128.32.255.10)  11.67 ms  13.90 ms  13.32 ms18  arachne.Berkeley.EDU (169.229.131.109)  12.27 ms  8.01 ms  8.05 ms

555© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

International Traceroutetraceroute to bells.cs.ucl.ac.uk (128.16.5.31), 30 hops max, 40 byte packets 1  sjcm-dc-gw1.cisco.com (171.69.25.2)  0.83 ms  0.67 ms  0.85 ms 2  sjce-sbb1-gw1.cisco.com (171.69.14.113)  0.47 ms  1.43 ms  0.41 ms 3  sjce-rbb-gw1.cisco.com (171.69.14.33)  0.44 ms  0.37 ms  0.34 ms 4  sj-wall-1.cisco.com (171.69.7.170)  0.39 ms  0.37 ms  0.35 ms 5  sjce-dirty-gw1.cisco.com (128.107.240.197)  1.65 ms  0.68 ms  0.61 ms 6  sjc-k-isp-gw1.cisco.com (128.107.239.90)  1.94 ms  1.53 ms  0.62 ms 7  POS2-3.GW5.SJC2.ALTER.NET (65.208.80.241)  2.28 ms  3.43 ms  2.35 ms 8  161.ATM5-0.XR2.SJC2.ALTER.NET (146.188.144.54)  2.62 ms  1.41 ms  1.22 ms 9  0.so-1-0-0.XL2.SJC2.ALTER.NET (152.63.56.141)  3.11 ms  2.27 ms  1.57 ms10  0.so-3-0-0.TL2.SAC1.ALTER.NET (152.63.54.10)  5.77 ms  4.80 ms  4.77 ms11  0.so-7-0-0.IL2.NYC9.ALTER.NET (152.63.9.185)  71.02 ms  69.89 ms  69.77 ms12  so-1-0-0.IR2.NYC12.ALTER.NET (152.63.23.70)  71.09 ms  69.91 ms  70.65 ms13  so-5-0-0.TR1.LND9.Alter.Net (146.188.15.49)  142.83 ms  141.74 ms  141.50 ms14  so-5-0-0.XR2.LND9.Alter.Net (146.188.15.38)  146.52 ms  144.97 ms  145.10 ms15  pos2-0.gw1.lnd9.alter.net (158.43.150.146)  142.46 ms  141.63 ms  142.83 ms16  ukerna-gw.pipex.net (158.43.37.202)  142.69 ms  141.64 ms  141.42 ms17  po15-0.lond-scr.ja.net (146.97.35.137)  142.95 ms  141.62 ms  141.63 ms18  po0-0.london-bar1.ja.net (146.97.35.2)  142.86 ms  141.86 ms  141.74 ms19  146.97.40.34 (146.97.40.34)  142.89 ms  141.81 ms  141.81 ms20  ucl.lmn.net.uk (194.83.101.6)  146.57 ms  145.71 ms  145.40 ms21  128.40.20.61 (128.40.20.61)  143.63 ms  142.67 ms  143.36 ms22  128.40.20.14 (128.40.20.14)  147.24 ms  145.81 ms  145.76 ms23  cisco.cs.ucl.ac.uk (128.40.14.1)  147.48 ms  145.97 ms  145.84 ms24  bells.cs.ucl.ac.uk (128.16.5.31)  172.75 ms  142.54 ms  146.16 ms

666© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Autonomous System Interconnection

• AS:

“A routing system using a single protocol and under common administration”

• AS in center

High connectivity

• AS at edge

Low connectivity

Major ISPs

Access Networks

777© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Routing by contract

• BGP Routing is essentially routing by contract

Goal is not to achieve a good route, but a usable one for which money changes hands

• Broad contract categories:

“Peering”

“Transit”

888© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Peering Contracts

• Contract among equals

“I will advertise my customers to you”

To get full routes, have to peer with every major network

• Relatively expensive to service

Packets that enter my network will always be delivered in my network

Peering contracts may produce little or no revenue, as they are essentially a trade for access to peer’s customers

999© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Transit contracts

• Contract between provider and customer

“I will advertise the ability to get anywhere”

Often some combination of default and individual routes

“Full” routes can be gotten from any major provider, but may be inefficient routes.

• Relatively inexpensive to service

Packets often handed to next hop network quickly,

Packets only sometimes spend time in my network

However, transit contracts produce revenue

101010© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Components of agreements

• Contracts always under NDA

Therefore little direct knowledge outside key players

• Key components

Routes advertised

Ability to advertise routes

Assigned Prefix (Enterprise)

Multihoming

Applied bandwidth

Load threshold at which bandwidth is increased

Delay and loss rates acceptable

Uptime requirements

Cost of service

Flat Rate or Usage Pricing

111111© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Queuing Theory and QoS

0

10

20

30

40

50

60

70

80

90

0% 3% 6% 9% 12%

15%

18%

21%

24%

27%

30%

33%

36%

39%

42%

45%

48%

51%

54%

57%

60%

63%

66%

69%

72%

75%

78%

81%

84%

87%

90%

93%

Mean 99.8% Confidence

Nominal Delay and Jitter Greater Delay, Jitter, and Loss

Link utilizationMe

an

qu

eu

e d

epth

, an

d t

he

refo

re d

ela

y

ratedeparture

ratearrival

1DepthQueue

2

2

)1(

2

2

)1(

121212© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Key issues is supporting SLA

• Fundamentally, the issue is

Bandwidth and

Reachability

131313© 2001, Cisco Systems, Inc. All rights reserved.Presentation_ID

Key problems in global routing

• Asymmetric Routes resulting from differences in policy

• Convergence issues resulting from

Differences in policy

Algorithms and parameters in routing

14© 2001, Cisco Systems, Inc. All rights reserved.

Session NumberPresentation_ID

Structure of the Internet

Fred Baker