Lecture-09 - Lecture#09 Network Layer Objectives...

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Unformatted text preview: Lecture #09 Network Layer Objectives “Best-Effort Delivery End-to-End” • Functions – robust delivery of packets end-to-end • packet routing • routing past failures • scalability – globally unique addressing – adherence to layering abstraction (where possible) • independent of data link layer • hide details from transport layer • Protocols – Most common example is IP – There are others but not worth covering Internet Structure: Network of Networks • “Tier-2” ISPs: smaller (often regional) ISPs – Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs Tier-2 ISP Tier-2 ISP Tier-2 ISP pays Tier-2 ISPs also peer rivately with Tier 1 ISP Tier 1 ISP Tier 1 ISP NAP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP tier-1 ISP for connectivity to rest of Internet b tier-2 ISP is c u s t o m e r of tier-1 provider privately with each other, interconnect at NAP Internet Structure: Network of Networks • “Tier-3” ISPs and local ISPs – last hop (“access”) network (closest to end systems) Tier-2 ISP Tier-2 ISP local ISP local ISP local ISP local ISP Tier 3 ISP Local and tier- Tier 1 ISP Tier 1 ISP Tier 1 ISP...
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This note was uploaded on 02/19/2012 for the course ENGR 361 taught by Professor Drexel during the Spring '12 term at Bloomsburg.

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Lecture-09 - Lecture#09 Network Layer Objectives...

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