congestion can be either logical or physical Meanwhile, insufficient bandwidtha resource shortageon physical links between routers and the network can also be a bottleneck, resulting in congestion. Resource shortage can occur
At the link layer , where the link bandwidth runs out
At the network layer , where the queues of packets at nodes go out of control
At the transport layer , where logical links between two routers within a communication session go out of control
Control the rate at which packets are sent (not just how many). Widely used in ATM networks.
Leaky Bucket Algorithm used to control rate in a datagram network.
we will not follow ATM network concept in gate