the journey active network model maximilian ott et al. ieee journal on selected areas in...
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The JOURNEY Active Network Model
Maximilian Ott et al.IEEE Journal on Selected Areas in Communications, vol.19, no. 3, March 2001
Introduction
Processing at the terminal endProcessing at the server end
The goal is to provide processing as an additional network service.The request-response processing model is transferred to continuous transformations on the date streams.
JOURNEY Network Model
The transformation of a media unit (MU) is considered as a independent processing job.
A sequence of jobs pass through a JOURNEY node, which consists of multiple stages: Classification stage Admission stage Routing stage
Computation as a Network Service
Streams of MUs are injected into the network for routing and customizing.
An MU is independently processed anywhere along the path guided by routing.
A computing router utilize local condition of resource availability for deciding whether to process an MU.
Computation as a Network Service
Similar to IP networks, the best-effort processing collocates with error recovery at higher layers.
Customization information can be originated at any point of the stream path, such as a client node or a resource manager.Specific path routing is required for dealing with fragmentation of MUs. (MPLS, IP source routing)
Computing Router Architecture
The cluster-based active router architecture (CLARA) Routing element Computing element(s) System area network (SAN) Cluster manager
Router Programming Framework
The CLARA software framework is also designed to support: Accounting of the resource utilization of a
packet or stream;
Division and vending of portions of the computational resources available on a router;
Dynamic addition of customization functionality Functionality repositories
Admission Control for Soft-QoS Guarantees
Unprocessed packet rate (UPR)Packet Admission Control (PAC)
:observed delay for a packet:estimator function:current processing backlog
:upper bound processing:packet’s delay budget
Cascade Transformations with Multiple Nodes
The performance goal of the active network is to bring the UPR of flows below some acceptable value.
Experience and EvaluationMedia gateway
Dropping frames, removing color, stronger uniform compression
Meta-information MPEG4, MPEG7
The trend toward thin and mobile clientsThe scalability problem at the gateway
Analysis
The larger the input/output bit-rate ratio, the less time it takes to transcode. Frame drop and/or spatial resolution adjustmen
ts DCT requantization
The total store-processing forward-service is double the processing time. User-space routing engine IP over Myrinet
Scalability in JOURNEY
Manageability Self-configuration and self-healing
AvailabilityPerformance Number of computing routers
Conclusions
The JOURNEY network model provides computation as a scalable network services.
The computation model trades off hard guarantees for computation in favor of architectural simplicity.
The CLARA architecture collocates computing and routing functionality.
Future Works
Studying the performance of the admission control and routing mechanisms at different traffic loads
Development of a management framework for the discovery and on-demand deployment of transcoding services
Development algorithms for admission control and load distribution within a CLARA computing router
Possible Directions
Handing computation from proxies into the network
Mobile computing, WAP
Improving efficiency of multicast routing with heterogeneous receivers
Pre-customization of data streams
Active flow and congestion control Re-transcoding and/or re-routing of data streams
Layered multimedia multicast tree