Is the regulation of the rate at which flows are allowed
to inject packets into the network and is therfore one of the cornerstones of any
QoS architecture. Bucket mechanisms are abstractions that can be used to
characterize the traffic rate.
Token Bucket A Token Bucket consists of a bucket that can hold up
to b tokens. Tokens are generated at a constant rate of r tokens per second
and added to the bucket as long as it is not filled completely. Each packet
transmitted into the network must first remove a token from the token bucket.
If the bucket is empty, the packet must wait for a new token or alternativly
it is dropped or marked with a lower priority. A token bucket is able to
police a bursty data stream with the average rate r and a maximum burst
size of b packets.
Leaky Bucket A Leaky Bucket consists of a bucket that is able to
hold up to b packets. Packets are stored in the bucket and delayed until
they are transmitted with a constant rate r into the network. Leacky buckets
are used to police data streams with a constant rate r.
The animation allows you to select a token or a leaky bucket and to set
different parameters of the bucket algorithms.