Fleksibilni Internet servisi na bazi kontrole kašnjenja i

where wi(t) is the waiting time of the packet and si is the delay differentiation parameter
of class i. Setting the delay differentiation parameter si to a larger value results in a lower
delay experienced by packets in class i. It has been shown [12], [24] that average waiting
time for any two classes i and j serviced by WTP satisfies:
di j
→ (8)
d
j
under heavy-load conditions. Therefore, choice of delay differentiation parameters si and
sj determines the ratio of average queuing delays in these two classes.
Fig. 6. Traffic classes in EDS model receive asymmetric loss and delay performance.
23
s
s
i
PLR dropper [24] is a packet dropping mechanism that closely approximates
proportional loss rate differentiation between classes. PLR maintains estimates of loss
rates li in each class. When an active queue management (AQM) algorithm in a router
decides that a packet should be dropped, PLR selects the backlogged class with the
minimum normalized loss rate li/σi, where σi is the loss differentiation parameter of class
i, and drops a packet from class i. Dropping a packet from class i tends to equalize