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Published byLeon Cole Modified over 7 years ago
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Carrier/Network Perspectives Cross-Layer Optimization (CLO) Bar Bof
© 2010 Telefónica Investigación y Desarrollo, S.A. Unipersonal
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01 Why cross layer? A little bit of history…
Layering was introduced to provide abstraction Complexity for building applications is reduced However… information is lost Network layers are unaware of the detailed applications needs for the network This can lead to an inefficient use of the network, and unexpected application behaviour What can we do? Include extra information in the headers (mark packets, extended info in RTP headers…) Closer integration between application data and control (e.g. congestion notifications…) Collaboration of network infrastructure (e.g. caching, resource) with application signaling, e.g. explicitly reserving bandwidth Cross layer optimization
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02 Services Individual services
Services consumed by residential users. Typical services will include VoD and online gaming. Individual services with high requirements. Services consumed by companies / research centers involving a single application. Typical example will be a dedicated high bandwidth connection (backup service, connection to a remote device) Aggregated services The connection is used for a bunch of services with similar QoS requirements.
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Understanding the application requirements
03 Understanding the application requirements Delivery parameters Bandwidth demand (bit-rate) (peak demand) Packet Loss: How sensitive is the service to packet loss? Level of resiliency needed Latency: Real-Time demand Jitter: Latency variation Video specific: Codec, Quality of the source material, e.g. quantization factor used in mpeg encoding Elasticity: how well a service lends itself at having a different delivery rate compared to the play-out rate at the end-user. Real-time services or live services are not elastic. Additional parameters, total volume: Is the service volume (in bytes) known? How small/large is this volume? Symmetric: Is it symmetric or asymmetric (upstream-downstream) traffic. Are both directions equally important?
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Understanding the application requirements
04 Understanding the application requirements Consumption parameters Availability Start-up delay Consumption delay Interactivity
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Proposals and Solutions
06 Proposals and Solutions OGF Network Service Interface Service interface between a requesting software agent and the provider software agent that offers and delivers a network service SCAP Implementation of transport with transparent intermediate buffering & deadline scheduling Hop-by-hop request / reply mechanism Meta-information in playmap
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05 Use case of service with high network interaction: Nomadic Virtual PC The virtual PC: a virtual terminal which is executed on a remote host, and is accessed through the “remote desktop” capabilities of a standard Windows or MacOS terminal at home. A nomadic Virtual PC service would require the transfer of data between servers in near real time (microseconds) timescale . Example: consider a given user which is in the coverage area of a. The server at the local node asks the rest of the servers in the operator network for her virtual machine, which is immediately downloaded. As a result, the virtual PC is very close in propagation distance from the user, and the feeling of interactivity is very high.
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Acknowledgements Part of the ideas come from the research project RUBENS, and the ongoing projects MAINS
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© 2010 Telefónica Investigación y Desarrollo, S.A. Unipersonal
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