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Learn about reliable multicast, active networks, active local recovery, subcast features, and strategies for efficient reliable multicast protocols in grid applications. Discover the benefits of global and local NACK suppression, subcasts from source and routers, and the impact of active router density on throughput.
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Active reliable multicast strategies for Internet-based grid computing infrastructures M. Maimour & C. Pham
What is a computational grid? application user from Dorian Arnold: Netsolve Happenings
Some grid applications Astrophysics: Black holes, neutron stars, supernovae Mechanics: Fluid dynamic, CAD, simulation. Distributed & interactive simulations: DIS, HLA,Training. Chemistry&biology: Molecular simulations, Genomic simulations.
What is reliable multicast? Sender • Not n-unicast from the sender perspective • Efficient one-to- many data distribution • No data losses data data data data Receiver Receiver Receiver
Examples data & program distribution collective & gather operations synchronization barriers SDSC IBM SP 1024 procs 224.2.0.1 NCSA Origin Array 256+128+128 procs CPlant cluster 256 nodes application user Multicast address group 224.2.0.1
What is active networks? • Programmable nodes/routers • Customized computationson packets • Standardized execution environment and programming interface • No killer applications, only a different way to offer high-value services, in an elegant manner • However, adds extra processing cost
Motivations behind active networking • user applications can implement, and deploycustomized services and protocols • specific data filtering criteria (DIS, HLA) • fast collective and gather operations… • globally better performances by reducing the amount of traffic • high throughput • low end-to-end latency
data data Active networking illustrated • Specific code can be applied on the packet • Integrated and discrete approaches • High flexibility to define new services data
where to put active components? 1000 Base TX active router active router core network Gbits rate Server active router active router 100 Base FX active router
NACK4 Active local recovery • routers perform cache of data packets • repair packets are sent by routers, when available data data data5 data1 data2 data1 data3 data2 data4 data3 data5 data4 data5 data4 data1 data2 data3 data5
NACK4 NACK4 data4 NACK4 NACK4 only one NACK is forwarded to the source by the router: global NACK suppression NACK4 Active feedback aggregation • Routers aggregate feedback packets
data4 NACK4 data4 NACK4 data4 data4 data4 NACK4 data4 data4 NACK4 data4 data4 data4 data4 Active subcast features • Send repair packet only to the relevant set of receivers
Network model F active routers among N. B receivers in a local group 2 kinds of receivers: linked and free
Active reliable multicast strategies • S1 : global NACK suppression • S2 : local NACK suppression • S2S : + subcast from the source • S3 : global NACK suppression subcast from the routers • S3S : + subcast from the source
Conclusions • Efficient reliable multicast protocols are a big win for grid applications • Active networking can really help enhancing the reliable multicast performances • global NACK suppression is easy to implement, and allows subcast from routers • local NACK suppression performs well for high loss rates but is difficult to tune • subcasting is very interesting when the number of receivers is large