Traffic Management for the Available Bit Rate (ABR) Service in ...

5.5.6 Parking Lot
Figure 5.14: Three-source con guration
This con guration is popular for studying fairness. The con guration and its
name was derived from theatre parking lots, which consist of several parking areas
connected via a single exit path. At the end of the show, congestion occurs as cars
exiting from each parking area try to join the main exit stream.
For computer networks, an n-stage parking lot con guration consists of n switches
connected in a series. There are n VCs. The rst VC starts from the rst switch and
goes to the end. For the remaining ith VC starts at the i ; 1th switch. A 3-switch
parking lot con guration is shown in Figure 5.17. The simlation results are shown
in Figure 5.18. Notice that all VCs receive the same throughput without any fair
queueing.
5.5.7 Upstream Bottleneck
This con guration consists of four VCs and three switches as shown in Figure 5.19.
The second link is shared by VC2 and VC4. However, because of the rst link, VC2
is limited to a throughput of 1/3 the link rate. VC4 should, therefore, get 2/3 of
the second link. This con guration is helpful in checking if the scheme will allocate
all unused capacity to those source that can use it. Figure 5.20 show the simulation
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