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Results

With the above architecture, AF and EF classes can be configured by the user with different priorities and BW requirements. To demonstrate the working of priorities among the different AF classes, all the AF classes were allocated equal bandwidths (1 Mbps) and the results are as follows,

Flow Type Priority Throughput at Tx( Mbps) Throughput at Rx (Mbps)
AF class4 2 1.09 0.906
AF class3 3 1.09 0.861
AF class2 4 1.09 0.806
AF class1 5 1.09 0.776

Note that lesser the numerical value of priority, more the priority for the class, i.e AF class4 has a higher priority than AF class1. We can observe a clear difference in the throughput among the different AF classes.

Also to see the coexistance of AF, EF and BE, a few tests were performed and their results are summarised below. The BW and priority allocations for the different classes are as follows,

Flow Type Priority BW allocation (Mbps)
EF PHB 1 2.0
AF PHB 2 8.0
AF class1 5 1.5
AF class2 4 1.5
AF class3 3 2.0
AF class4 2 2.5
BE 7 0.5

Data for the various classes were pumped in through ttcp, ttcp was modified to set the TOS byte in the packets. It can be found that the traffic flow through the appropriate classes, this can be observed with the show in tc.

The results:

Flow Type Throughput at Tx (Mbps) Throughput at Rx (Mbps)
EF flow1 1.014 1.011
EF flow2 1.014 0.989
AF class4 2.420 2.378
BE 0.979 0.468

Observe that the two EF flows together get almost close to what was allocated for EF and BE seem to be affected in the presence of other flows.

Another set of results

Flow Type Throughput at Tx (Mbps) Throughput at Rx (Mbps)
EF flow1 1.014 1.014
EF flow2 1.014 0.994
AF class4 2.420 2.379
AF class2 1.405 1.368
BE 0.979 0.489


next up previous contents
Next: EF_BE Model Up: Diffspec - A Differentiated Previous: Architecture   Contents
Anupama Sundaresan
1999-12-19