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

6.22.4 Fairness
Figure 6.9: Parking lot con guration
Two con gurations are used for studying the fairness of the scheme: the parking
lot con guration and the upstream con guration. The parking lot con guration and
its name were 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 series. There are n VCs. The rst VC starts from the rst switch and
goes through all the remaining switches. For the remaining VCs, the i th VC starts
at the i ; 1 st switch. The link between the last two switches is the bottleneck link.
The max-min allocation for each VCis1/n of the bandwidth. A 3-switch parking lot
con guration is shown in gure 6.9. Figure 6.15 illustrates that ERICA achieves the
desired max-min allocation.
Although the parking lot con guration had been believed to test fairness, we
discovered that it is not su cient to demonstrate max-min fairness, and a more
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