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Explore advanced congestion control algorithms, policies, and mechanisms at different network layers. Understand their impact, from data link level retransmission to transport level QoS establishment, for optimal traffic management.
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Algorithms for Congestion Control • C.c. open loop • acting on SOURCE • acting on DESTINATION • c.c. closed loop • explicit feedback • implicit feedback
Influence on Congestion • Data Link level • retransmission policy • out-of-order packet caching • confirmation policy • flux control policy • Network level • virtual circuit or datagrams • management of packets in routers • packet elimination policy • routing algorithms • management of “time-to-live” • Transport level • retransmission policy • out-of-order packet caching • confirmation policy • flux control policy • establishing the TIME OUT
QOS for transport layer • Connection establishment delay; • connection establishment failure probability; • transit delay; • residence error rate; • transfer error probability; • connection release delay; • connection release failure probability; • protection; • resilience; • option negociation;
The token bucket algorithm • C+*S = M*S • S = C/(M - ) • S - the output burst length (sec); • C - the bucket capacity (nr. bytes); • - the arriving token rate ( bytes/sec); • M - the maximum output rate (bytes/sec)