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Internet infrastructure and access

Internet infrastructure and access. Henning Schulzrinne Dept. of Computer Science Columbia University Fall 2003. Internet backbones. Classify ISPs into tiers tier 1: global reach, about 40 British Telecom (BT), Cable & Wireless, Global Crossing, Level 3, Sprint, MCI (UUnet), Verio (NTT), …

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Internet infrastructure and access

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

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

  3. Internet backbones • 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) • 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

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

  5. ISPs • Many dial-up ISPs don’t own modems  use wholesale providers • DSL + cable modem • modems are always oversubscribed (10:1?)

  6. Residential broadband

  7. Quick review: DSL • Uses spectrum from 25 kHz 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

  8. Commercial international backbone

  9. Internet2 backbone (Abilene)

  10. Internet2 (Abilene) 10 Gb/s network

  11. Peering • Exchange of traffic between ISPs • autonomous systems (AS) • private peering vs. public peering • 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 (tier2  tier1)

  12. Peering points: AMSIX in Amsterdam

  13. Peering point: AMSIX

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