The parameter D at each service element should be set to the maximum packet transfer delay (independent of bucket size) through the ser- vice element. For instance, in a simple router, one might compute the worst case amount of time it make take for a datagram to get through the input interface to the processor, and how long it would take to get from the pro- cessor to the outbound interface (assuming the queueing schemes work correctly). For an Eth- ernet, it might represent the worst case delay if the maximum number of collisions is experi- enced. The error term D is measured in units of one microsecond. An individual element can adver- tise a delay value between 1 and 2**28 (some- what over two minutes) and the total delay ad- ded all elements can range as high as (2**32)- 1. Should the sum of the different elements delay exceed (2**32)-1, the end-to-end delay should be (2**32)-1.