cdn mechanisms
DESCRIPTION
CDN Mechanisms. The Client-Server-Resource model for Content Distribution Networks of varying node dynamics and density. Similar network models: Grid, Peer-to-Peer, CDN. Grid. Computational GRIDs - PowerPoint PPT PresentationTRANSCRIPT
19/04/23 cdn mechs.ppt
CDN Mechanisms
The Client-Server-Resource model for Content Distribution Networks of varying node dynamics and density
Similar network models: Grid, Peer-to-Peer, CDN
19/04/23 cdn mechs.ppt
Grid
Computational GRIDs basic layer for harnessing processing power by
distributing massive computational tasks to numerous resources (compute cycles and data storage) over matching communication links.
data archives
instruments
MPPsclusters
workstations widearea
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More grids
Information and knowledge GRIDs allowing access to dispersed information, and knowledge
discovery and extraction from spread knowledge resources. They make use of cognitive techniques and tools such as data mining, machine learning, content semantics, ontology engineering, information visualisation and intelligent agents.
Grid technologies are also to be interpreted in a broad sense including technologies for Peer-to-Peer Computing (P2P) using commodity hardware to enable the co-ordinated use
of geographically distributed resources without central control.
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Peer-to-peer Network
Classic definition "A type of network in which each workstation has
equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others." [Webopedia]
Modern (ad hoc) definition P2P is a class of applications that takes advantage of
resources --storage, cycles, content, human presence-- available at the edges of the Internet. P2P nodes must operate outside the DNS system and have
significant or total autonomy from central servers…
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CDN
Content distribution networks are coordinated caching systems.
CDNs are a multi-million-dollar business already.
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A DNS-redirecting CDN
DNSredirector
Client
HTTPserver
HTTPserver
HTTPserver
A
B
C
example.com ?
B
GET http://example.com/foo
http://example.com/foo
Network Model
Network Model
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Mechanisms
Deployment: where service is located ( Cooperation:
Query routing Consistency
Internal resource management: Replacement Prefetching
Selection (based on dns, multicast, anycast, metrics) request distribution Server selection
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Scenarios
Node dynamics: Hosts close to backbone, dedicated, permanent, versus
PC close to network edge, part-time, eventual, transient
Node density About 10K nodes (Akamai) About 100K-1000K nodes &+ (gnutella, freenet,
morpheus, etc.)
BLCA
Nodedynamics
Node density
AKAMAI
Morpheus / P2P
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Organisation
Tree, grid or any other “organised” topology (CDN) Mesh, small network topology (P2P)
E.g. map of the gnutella network
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Xweb
Web OS, Active ServicesWeb
Content Distribution Networks
Per overlay (garantee service, mgmt)
Dynamic Programming
Manual Modifications
Service Control
Programmability
None (Best-effort Service, No
mgmt,...)
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Solution: XWeb
DM
Spawn
Spawn
Spawn
Squid
Squid
Squid
parent
parent
avant
pc1
pc2
mosaicRA
RA
RA
RA
DM
Deployment Manager @ Service Providers
Resource Agent @ Resource Providers
Deployment Mechanisms
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WWG/laColla P2P environment for group collaboration
Reduced scale groups on a large scale network
Event distribution based group communication Three mechanisms:
Event distribution (to group members)
Group membership Repository agents
(where history and documents are stored)
Simulation (JavaSim)
The number and locationdepends on many factors
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A Demand based Algorithm for Rapid Updating of Replicas
Simulation (Network Simulator NS)
A Distributed Magazine ... demand is an important+changing factor ...
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Influence of the Document Validation/Replication Methods onCoop. Web Proxy Caching Performance of cooperative web
caching schemes (hieracy, mesh, hybrid) with
different doc. validation/replication methods (TTL, invalidation, pushing, etc.)
Cost: combination of factors Response time Bandwidth consumption Number of stale docs
Simulation (Network Simulator NS)