as a jitter or delay variation tolerance, or as a maximum burst size (MBS). Multiple sets of contract parameters can be applied concurrently to a connection using multiple instances of the leaky bucket algorithm, each of which may take a bandwidth and a burstiness limit: see . Emission interval The rate at which the bucket leaks will determine the bandwidth limit, which is referred to as the average rate by Turner and the inverse of which is referred to as the emission interval by the ITU-T. It is easiest to explain what this interval is where packets have a fixed length. Hence, the first part of this description assumes this, and the implications of variable packet lengths are considered separately. Consider a bucket that is exactly filled to the top by preceding traffic, i.e. when the maximum permitted burstiness has already occurred, i.e. the maximum number of packets or cells have just arrived in the minimum amount of time for them to still conform to the bandwidth and jitter limits. The minimum interval before the next packet can conform is then the time it takes for the bucket to leak exactly the amount of water delivered by a packet, and if a packet is tested and conforms at that time, this will exactly fill the bucket once more. Thus, once the bucket is filled, the maximum rate that packets can conform is with this interval between each packet. Turner refers to this rate as the average, implying that its inverse is the average interval. There is, however, some ambiguity in what the average rate and interval are. Since packets can arrive at any lower rate, this is an upper bound, rather than a fixed value, so it could at best be called the maximum for the average rate. Also, during the time the maximum burstiness occurs, packets can arrive at smaller intervals and thus at a higher rate than this. So, for any period less than infinity, the actual average rate can be (but isn't necessarily) greater than this and the average interval can be (but isn't necessarily) less than the emission interval. Hence, because of this ambiguity, the term emission interval is used hereafter. However, it is still true that the minimum value that the long-term average interval can take tends to be the emission interval. For variable-length packets, where the amount added to the bucket is proportional to