US Robotics USR2410 Manual de usuario descargar pdf (Pagina 53)

Table 8-2: Averaged Collected Data from No. of Hops Tests

Test Type/ Number of Hops 1 Hop 2 Hops 3 Hops

TCP: Test 5MB File Download

Avg. Thoughput (Bps) 201723 213967 159735

Avg. Round Trip Time (s) 0.00054 0.00046 0.00034

UDP: Date Stream Test

Avg. Thoughput (Bps) 102169 41920 92365

Avg. Round Trip Time (s) 0.01294 0.09978 0.01458

8.3

System Load

This test was used to examine how well the network handled a high load. This was examined at 5

hops and the number of packets was adjusted per second until the network suffered from a packet

loss rate of 10% or more. D-ITG was used to test both TCP and UDP protocols on the system and

data recorded.

Acquisition of data for high load situations was not feasible due to the memory leak in the

Madwifi driver. System memory was used up very quickly causing the memwatch script to

reload both Click and the driver. Although the memwatch program was in place to add stability

to the mesh network, whenever a mesh router was restarted the traffic flow stopped, and all

packets were dropped until the mesh router came back online and was recognized by its

neighbors. This meant that the load the network could handle was arbitrarily small, since any

amount of traffic would eventually cause a mesh router to temporarily leave the network. This

intermittent failure of nodes throughout the system, especially when testing a linear topology

caused any collected data to not be representative of network performance and the data was

dismissed.

8.4

Fairness

The definition of fairness in a network is equitable treatment of separate clients on a mesh

network sharing the same physical medium and channels. In multi hop networks throughput is

reduced as you increase the number of hops.[9] Fairness will be examined with the last statement

in mind to test effect this has in terms of throughput and packet delay to the clients.

The testing was performed setting a client at the final hop and moving the second client through

all other hops and examining the throughput of the network on each client though ethereal.

Figure 8-2 shows the topology used for testing where client one fixed and the other clients

represented by the dotted lines move through the network.

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US Robotics USR2410 Manual de usuario Pagina 53