structure of the internet
DESCRIPTION
Structure of the Internet. Fred Baker. The optical internet backbone Gigabit to terabit links. Access networks xDSL, cable modem, ISDN, asynchronous dial 20,000 instantaneous sessions per GBPS backbone bandwidth. Today’s Internet. Campus Networks (LANs). UoSAT-12. Internet in Airlines. - PowerPoint PPT PresentationTRANSCRIPT
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%
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30%
33%
36%
39%
42%
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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
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ratedeparture
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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