Performance Report for A5483A, A5513A, and A5515A ATM/155 and ATM/622 Adapters
Performance Report on ATM adapters, Part No. A5483A, A5513A, and A5515A 09/30/99 2
The packet size (that is, the Maximum Transmission Unit [MTU] size) and the interface type
influence the performance of the adapters. Table 2 below shows the maximum TCP throughput
and CPU utilization figures for three 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 various Interface Types (N4000 system, One CPU, 155 Mbps Adapter)
Test/Interface
Classical IP
MTU 9180 bytes
LANE
MTU 9218 bytes
LANE
MTU 1516 bytes
Outbound Mbps 134.45 134.13 128.4
CPU Utilization % 6.5 8.4 10.4
Inbound Mbps 132.03 132.38 128.22
CPU Utilization % 5.65 6.42 8.49
Bidirectional Mbps 260.12 258.14 240.25
CPU Utilization % 11.17 12.24 17.8
Table 3: TCP Throughput on various Interface Types (N4000 system, 1 CPU, 622 Mbps Adapter)
Test/Interface
Classical IP
MTU 9180 bytes
LANE
MTU 9218 bytes
LANE
MTU 1516 bytes
Outbound Mbps 538.14 533 448.
CPU utilization % 26.85 28.58 88.79
Inbound Mbps 535.42 537 454.48
CPU Utilization % 23.61 25.52 20.05
Bidirectional Mbps 1005 965 453.15
CPU Utilization % 57.1 77.14 71.27
The TCP window size is an important parameter that affects throughput performance. For 622
Mbps adapters, the TCP window size on the receiving end must be set to at least 144Kbytes
(instead of the default window size of 64 Kbytes) to achieve the maximum throughput. For 155
and 622 Mbps adapters, the window size of 144 Kbytes also minimizes the sensitivity to
application messages size. See Figure 1 below for an example of Outbound Throughput.
Figure 1: TCP Window Size and Outbound TCP Throughput on N4000 (Classical IP, 622 Adapter)
TCP Window Size and Throughput on N4000- 622 Card
0
100
200
300
400
500
256
512
1024
1536
2048
2560
3072
3840
4096
4352
7936
8192
8448
10240
32768
57344
65536
1E+05
Message Size in Bytes
Throughput Mbps, CPU Utilization %
Throughput (Window Size = 64
Kbytes)
CPU Utilization (Window Size
= 64 Kbytes)
Throughput (Window Size =
144 Kbytes)
CPU Utilization (Window Size
= 144 Kbytes)