Meta-Headers: Top-Down Networking Architecture with Application-Specific Constraints Murat Yuksel University of Nevada, Reno Reno, NV yuksem@cse.unr.edu http://www.cse.unr.edu/~yuksem IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 1
Motivation: The trends The variety of applications possible is increasing, especially in wireless wireless peer-to-peer, mobile data, community wireless The size is increasing: million-to-billion nodes The dynamism is increasing: vehicular networks, sensor networks, MANETs What is unavoidable?: More dynamism, more disruption tolerance, more entities, and more varieties IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 2
Motivation: The big picture Mobile, ad-hoc, dynamic Static Unstructured Structured Cross-layer & layered invariants Layered invariants Application Application-Specific Application Presentation Application Application Network-Specific Hardware-Specific ? Session Transport Transport Transport Network (TCP, UDP) (TCP, UDP) & Routing Network Network Network & MAC (IP) ? (IP, Mobile IP, Data Link Data Link 802.1x) (Ethernet 802.3) Physical Physical Physical Physical (RF, FSO, Fiber, Cable) (Fiber, Cable) (RF, Fiber, Cable) (a) OSI (b) Wireline (c) Wireless (d) MANET, peer-to-peer Economics always has the bigger force: economically attractive applications will keep forcing more vertical components into the stack! We need a systematic way of implementing vertical components to avoid an unhealthy monolithic stack architecture. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 3
Motivation: Response to the trends Wireless research has been responding with optimizing via cross-layer designs adding custom-designed vertical components to the stack Old hat: layered vs. cross-layer tradeoff Bottom-up cross-layer has been the main approach Scarcity of wireless resources dominated the economics IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 4
Motivation: Response to the trends A paradigm shift: wireless resources are becoming massively available Community wireless WiFi hotspots Google WiFi, AT&T Metro WiFi Spectrum resources may still be scarce but connectivity is already ubiquitous The key metric to optimize is becoming application utility rather than the wireless resources App-specific vertical designs are needed.. We need top-down cross-layer designs in addition to the traditional bottom-up ones. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 5
Why not continue merging layers? Merging layers: A greedy approach Makes it hard to standardize – bad for sw engineering Which layers must be absolutely isolated? Application, Network, Physical? Integrating lower level functions with a higher layer function will prevent them becoming a substrate for other higher layer protocols Cellular provisioning in the US – jailbreaks IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 6
Motivation: Application Layer Framing (ALF) Layering was a main component of the e2e architecture.. “a major architectural benefit of such isolation is that it facilitates the implementation of subsystems whose scope is restricted to a small subset of the suite’s layers.” Clark and Tennenhouse, SIGCOMM’90 But, Integrated Layer Processing (ILP) was there too! To achieve better e2e efficiency and resource optimization ILP never become a reality due to the lack of a systematic way of doing it. An ALF-based approach is needed: network protocol services at lower layers can best be useful when applications’ characteristics and intents are conveyed to the lower layers. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 7
Meta-Headers: A vertical design tool A packet meta-header: vertically travels across the network stack establishes a vertical communication channel among the traditional layers co-exist with the traditional per-layer packet headers Applications can communicate their intent across all the protocol layers by attaching the meta- headers to data. <meta-headers, message> IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 8
Headers vs. Meta-Headers Application-specific packet meta-headers Application message Layer 4 H4 MH4 MH3 MH2 MH1 message Explicit Meta-Headers Layer 3 H3 H4 MH4 MH3 MH2 MH1 message Layer 2 H2 H3 H4 MH4 MH3 MH2 MH1 message Layer 1 H1 H2 H3 H4 MH4 MH3 MH2 MH1 message Traditional packet headers Application-specific packet meta-headers Application message Layer 4 MH1 MH2 MH3 MH4 message Implicit Meta-Headers Layer 3 message MH1 MH2 MH3 H4 Layer 2 message MH1 MH2 H3 H4 Layer 1 message MH1 H2 H3 H4 message H1 H2 H3 H4 Traditional packet headers IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 9
Meta-Headers: Demultiplexing Protocol 1 Protocol 2 Demultiplexing with traditional headers message H4 MH4 MH3 MH2 MH1 Layer 4 Layer 3 message H3 H4 MH4 MH3 MH2 MH1 Demultiplexing with message H4 MH4 MH3 MH2 MH1 meta-headers Layer 4 Layer 3 H3 H4 MH4 MH3 MH2 MH1 message Service 1 Service 2 IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 10
Informing Applications about Lower Layer Services How will upper layers know about the service primitives of the layers lower than the one below? Reactive – Meta-Headers in Reverse Direction detect lower layer services in an on-demand manner as connections arise meta-headers rewritten by lower layers in reverse direction Requires a closed-loop – connectionless or multi- receiver services may not work IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 11
Informing Applications about Lower Layer Services (cont’d) Proactive – Pre-informed Designer inform layer k designers about services of layers k-2 and below apriori too much complexity as the number of lower layer services increases – rank ordering might help May not be desirable by ISPs Regional service discovery via broadcasting – connectionless IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 12
End-to-End Coordination 1 5 Application at Application at 4 source prepares source readjusts meta-headers with meta-headers for Meta-headers are filled default options and joint vertical with summary of sets flags to probe optimization of available end-to-end L1- for available end-to-end L4 services, and fed back services performance. to the source application. Application- Feedback loop for specific packet conveying end-to-end Application meta-headers Application message multi-hop L1-L4 services, possibly as a sequence of Layer 4 Layer 4 MH1 MH2 MH3 MH4 message MH1 MH2 MH3 MH4 message options over multiple hops. Layer 3 Layer 3 MH1 MH2 MH3 H4 message MH1 MH2 MH3 H4 message Optional Optional feedback Layer 2 Layer 2 MH1 MH2 H3 H4 message MH1 MH2 H3 H4 message feedback loop for local loop for Layer 1 Layer 1 MH1 H2 H3 H4 message optimization of last MH1 H2 H3 H4 message conveying hop(s) of the end- DESTINATION SOURCE available L1- to-end path. message message H1 H2 H3 H4 H1 H2 H3 H4 L3 services Traditional 2 3 packet headers Meta-headers may Meta-headers are filled or may not get with available L1-L3 converted to services, and traditional headers. optionally fed back to the source application. Layer 3 MH1 MH2 MH3 H4 message Layer 2 MH1 MH2 H3 H4 message A dynamic Layer 1 MH1 H2 H3 H4 message ROUTER end-to-end message H1 H2 H3 H4 negotiation.. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 13
An optimization perspective Meta-header Application probes Meta-headers questing lower Application-Specific Application-Specific filled with layer services Constraints View of the Network available services E B Lagrange Vertical (application-based (quality multipliers optimizations are cost) constraints) (pieces of Q 2 and Q 3 ) possible Top-Down Value Choice Value Optimization Framework Choices More dynamic Q 3 Lagrange W 3 multipliers (per-layer Meta-headers as (implicit) (pieces of E) W 2 state) (per-layer Q 2 Lagrange (implicit) constraints) (per-layer multipliers (per-layer Network State Network Resource state) constraints) Information Constraints Network Link State Link Resource Information Constraints Links IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 14
Summary A top-down networking architecture with meta- headers Vertical optimizations at finer temporal and spatial granularity A variety of top-down optimizations: Top-down routing (layers 5, 3) Top-down QoS/value management (layers 5, 3, 2) Top-down dynamic transport (layers 4, 3, 2) A new class of optimization problems aiming to improve joint performance of multiple layers while respecting the isolation among them. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 15
THE END Thank you! This work is supported in part by the U.S. National Science Foundation awards 0721600 and 0721609. IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 16
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