AS Numbers(ASNs ASNs are 16 bit values 64512 through 65535 are"private Currently over 15,000 in use Genuity: 1 ·MT:3 · JANET:786 UC San Diego: 7377 AT&T:7018,6341,5074, · UUNET:701.702.284,12199 Sprint:1239,1240,6211,6242, ASNs represent units of routing policy 2021/1/31 11
AS Numbers (ASNs) 2021/1/31 11 ASNs are 16 bit values 64512 through 65535 are “private” • Genuity: 1 • MIT: 3 • JANET: 786 • UC San Diego: 7377 • AT&T: 7018, 6341, 5074, … • UUNET: 701, 702, 284, 12199, … • Sprint: 1239, 1240, 6211, 6242, … • … ASNs represent units of routing policy Currently over 15,000 in use
Exampl ple 2.1 IGP 2.2 川 GR EGP 1.2 221 EGP EGP EGR 41|GP 4.2 EGP GP 5 3.1 3.2 IGP 5.1 5.2 2021/1/31 12
Example 2021/1/31 12 1 2 3 1.1 1.2 2.1 2.2 3.1 3.2 2.2.1 4 4.1 4.2 5 5.1 5.2 EGP IGP EGP EGP IGP IGP IGP IGP EGP EGP
A Logical View of the Internet Tier 1 ISP *“ Default-free"with 鹚 global reachability info Tier 3 Tier 2 ISP Tier 2 Regional or country Tier 2 Customer wide Provider tier 3 ISP Tier 1 Tier k loca Tier 2 2021/1/31 3
A Logical View of the Internet Tier 1 ISP “Default-free” with global reachability info Tier 2 ISP Regional or countrywide Tier 3 ISP Local 2021/1/31 13 Tier 1 Tier 1 Tier 2 Tier 2 Tier 2 Tier 3 Customer Provider
Transit vS Peering Transit($$ 1/2) Transit(SSS) ISP P ISPY Transit($ Transit($SS Transit(S$S ISPZ Peering ISP X Transit(S) Transit($S Transit($S 2021/1/31 14
Transit vs. Peering 2021/1/31 14 ISP X ISP Y ISP Z ISP P Transit ($) Transit ($$$) Transit ($$ 1/2) Transit ($$) Peering Transit ($$$) Transit ($) Transit ($$) Transit ($$$)
Customers and Providers provider provider Cl uStomer P traffic customer Customer pays provider for access to the Internet 2021/1/31 15
Customers and Providers 2021/1/31 15 Customer pays provider for access to the Internet provider customer IP traffic provider customer