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ECS 258: Internet QoS

ECS 258: Internet QoS. Lecture-1. Internet Architecture: An Overview. Internet is a gigantic network of networks Several autonomous systems interconnected in a hierarchical fashion Basic of Internet architecture: simple core facilitating intercommunications of smart edges

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ECS 258: Internet QoS

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  1. ECS 258: Internet QoS Lecture-1

  2. Internet Architecture: An Overview • Internet is a gigantic network of networks • Several autonomous systems interconnected in a hierarchical fashion • Basic of Internet architecture: simple core facilitating intercommunications of smart edges • Currently Internet uses Best Effort service model – delivery of data packets from a source to a destination will be done within a reasonable period of time if any possible path existed

  3. TCP/IP • Layered protocol stack facilitates isolation and design modularity • TCP runs transparently over IP network • Signaling and end-to-end state maintenance is avoided in IP • Unicast and multicast services • TCP connections interprets packet losses as congestion – fairness is maintained

  4. Network Connectivity • Network consists of links and routers • Routers use hop-by-hop forwarding techniques to send a packet towards its destination • Routing protocols select an appropriate path from a set of possible paths.

  5. Routing in Internet • Hierarchical IP address space facilitates routing of IP packets • Class-based hierarchy • Classless Inter-Domain Routing (CIDR) • IP networks uses shortest path routing • Routing Protocols: • Interior Gateway Protocols • Exterior Gateway Protocols

  6. Interior Gateway Protocols • Routing Information Protocol (RIP) uses distance vector (DV) algorithm • Open Shortest Path First (OSPF) uses link state (LS) algorithm • IGRP uses DV • IS-IS uses LS

  7. Exterior Gateway Protocols • Border Gateway Protocol version 4 (BGP4) • Facilitates inter domain routing • BGP runs on the border routers and enables them to distribute information about reachable networks • Uses a path vector protocol

  8. Best Effort Forwarding Model • Packets are routed using the shortest path without any guarantee or estimation of end-to-end delay, bandwidth or packet losses • The routers serve packets on a FCFS basis • During congestions packets are delayed or dropped randomly

  9. Quality of Service (QoS) • QoS relates to the service characteristics, which may be specified in quantitative or statistical terms of throughput, delay, jitter, packet losses, etc. • QoS can be provisioned through relative prioritization of resource allocation to different flows/packets in the network

  10. Need for QoS? • Evolving continuous media applications need real-time support and QoS guarantees • Prioritized services at a cost is desirable by several organization and enterprises • With the proliferation of e-commerce, service differentiation based on revenue or loyalty is highly desirable in such environment • Predictable and bounded delay will enhance the experience of Internet usage

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