Performance Report for J2468A, J2469A, J2499A, J3573A, and J2806CA ATM/155 and ATM/622 Adapters

Performance Report on ATM adapters 2
The packet size (that is, the Maximum Transmission Unit [MTU] size) influences the performance
of the adapters. Table 2 below shows the maximum TCP throughput and CPU utilization figures
for four different interface types for 155 Mbps adapters. Table 3 below shows the maximum
throughput and CPU utilization figures for the same interface types for 622 Mbps adapters.
Table 2: TCP Throughput on Different Interface Types (K580 system, One CPU, 155 Mbps Adapter)
Classical IP
MTU 9180 bytes
LANE
MTU 9218 bytes
LANE
MTU 4544 bytes
LANE
MTU 1516 bytes
Outbound Mbps 134.55 134.44 133.48 128.39
CPU Utilization % 8.14 9.20 12.19 22.74
Inbound Mbps 132.9 132.9 131.37 126.82
CPU Utilization % 10.92 13.68 14.01 14.96
Bidirectional Mbps 261 260.4 260.26 207.92
CPU Utilization % 22.8 24.77 35.56 67.04
Table 3: TCP Throughput on Different Interface Types (K580 system, 1 CPU, 622 Mbps Adapter)
Classical IP
MTU 9180 bytes
LANE
MTU 9218 bytes
LANE
MTU 4544 bytes
LANE
MTU 1516 bytes
Outbound Mbps 370.1 351.0 345.05 175.87
CPU utilization % 35.22 35.08 49.49 47.91
Inbound Mbps 540.4 480.53 396.9 237.53
CPU Utilization % 85.08 74.20 74.65 72.52
Bidirectional Mbps 584.5 527.9 396.2 236.65
CPU Utilization % 95.86 89.6 91.38 99.8
The TCP window size is an important parameter that affects throughput performance. For 622
Mbps adapters, the window size must to be set to 56Kbytes (instead of the default window size of
32 Kbytes) to achieve the maximum throughput. For 155 and 622 Mbps adapters, the window
size of 56 Kbytes also minimizes the sensitivity to application messages size. For example, see
Figure 1 below.
Figure 1: Window Size and Outbound TCP Throughput on J2240 (Classical IP, 155 Mbps Adapter)
Window Size and Outbound TCP Throughput J2240-155
0
20
40
60
80
100
120
140
0 2048 4096 6144 8192 10240
Message Size in Bytes
Throughput Mbps, CPU Utilization %
Throughput (Window
size = 32 Kbytes)
CPU Utilization (Window
Size = 32Kbytes)
Throughput (Window
Size = 56 Kbytes)
CPU Utilization (Window
Size = 56 Kbytes)