Queuing

Queuing

resource allocation

mechanisms where the network takes an active role in sharing resources amongst flows

router based resource allocation

within the network, router is responsible for deciding which packets are forwarded or dropped, and signalling capacity to hosts

host based resource allocation

edges of the network, hosts are responsible for adjusting their behavior to suit the observed network conditions

reservation based resource allocation

explicit resource requests usually sent by end hosts, accepted or rejected by routers on the path

feedback based resource allocation

no prior request, hosts send data and adjust based on feedback they receive

explicit feedback

message from an on-path device to slow down the sending rate

implicit feedback

host might detect increasing delays or packet losses

window based congestion control

specifying a sending window

rate based congestion control

specifying the rate that the application requires from the network

success of resource allocation metrics

effectiveness, fairness

congestive collapse

packets are delayed or dropped to the point that the network is no longer useful

FIFO

first packet to arrive is the first packet transmitted, tail drop queuing

FIFO with priority queues

each priority level has its own queue, allows high priority flows to starve low priority flows

fair queueing

work conserving - if there is a packet in any queue, the link will be busy