Internet infrastructure and access Henning Schulzrinne Dept of

Internet infrastructure and access Henning Schulzrinne Dept. of Computer Science Columbia University Fall 2003

Internet backbones l Classify ISPs into tiers – tier 1: global reach, about 40 l – – l tier 2: regional tier 3: local Tier-1’s typically use railroad tracks or pipelines as right-of-way – – l British Telecom (BT), Cable & Wireless, Global Crossing, Level 3, Sprint, MCI (UUnet), Verio (NTT), … some also lease (some) circuits from other providers at least 20, 000 fiber miles Connect to local circuits via points-of-presence (POP)

Internet backbones l l OC-3 (155 Mb/s), OC-12 (622 Mb/s), OC-48 (2. 4 Gb/s) or OC-192 (10 Gb/s) Usually, WDM or D-WDM (e. g. , 16 λ x 2. 5 Gb/s, up to 40 λ) – l l l 50 or 100 GHz optical spacing Fiber: about $30, 000 -$50, 000/mile, almost all construction Transport: POS (packet over SONET), MPLS, ATM, FR (edges) Backbone utilization: no more than 30% typical – needed for fault recovery

Network utilization l l local phone line: 4% U. S. long distance switched voice: 33% Internet backbones: 10 -15% private line networks: 3 -5% LANs: 1%

ISPs America Online dial 25. 3 MSN dial 8. 7 United Online (Juno) dial 5. 2 Earthlink dial 5. 0 Comcast cable 4. 4 SBC DSL 2. 8 Verizon DSL 1. 9 Cox cable 1. 7 Charter cable 1. 3 Bell. South DSL 1. 2 l l l Many dial-up ISPs don’t own modems use wholesale providers DSL + cable modems are always oversubscribed (10: 1? )

Residential broadband

Quick review: DSL l l l Uses spectrum from 25 k. Hz to 1. 1 MHz ATM cells Ethernet PPP DSLAM aggregates circuits US local loops can be up to 18 kft long ADSL+: 16 Mb/s @ 4 kft, 10 Mb/s @ 6 kft (1. 1 mi) downstream

Commercial international backbone

Internet 2 backbone (Abilene)

Internet 2 (Abilene) 10 Gb/s network

Peering l Exchange of traffic between ISPs – – l l autonomous systems (AS) private peering vs. public peering at MAE-East, MAE-West, AMS-IX, … either a LAN or mesh of ATM/FR VCs Sender keeps all (SKA) = only pay for rack space, not traffic Alternative: transit payment (tier 2 tier 1)

Peering points: AMSIX in Amsterdam

Peering point: AMSIX