Theoretical throughput in Netrounds Test Agents

This article discusses theoretical throughput performance of Ethernet/IP in Netrounds based on protocol overhead. We frame our theoretical reasoning in the context of Netrounds preinstalled Test Agents and their expected maximum performance. Beside overhead, there are other limiting factors which are not considered here, such as CPU limitations and overbooking of network links. Theoretical performance is calculated for Ethernet and for TCP/UDP over Ethernet. Read more about frame sizes here.

Ethernet data rates

The following table shows theoretical data rates in Netrounds UDP performance tests. The header is treated as payload in these calculations.

Protocol

Overhead (bytes)

Theoretical Data Rate (%)

Ethernet without 802.1q, 1518 byte frame size

8 preamble + 14 header + 4 CRC + 12 gap = 38 bytes/packet

(1500 + 18)/(38 + 1500) = 98.6996

Ethernet without 802.1q, 512 byte frame size

8 preamble + 14 header + 4 CRC + 12 gap = 38 bytes/packet

(494 + 18)/(38 + 494) = 96.2406

Ethernet without 802.1q, 64 byte frame size

8 preamble + 14 header + 4 CRC + 12 gap = 38 bytes/packet

(46 + 18)/(38 + 46) = 76.1905

 

 

 

Ethernet with 802.1q, 1518 byte frame size

8 preamble + 18 header + 4 CRC + 12 gap = 42 bytes/packet

(1500 + 22)/(42 + 1500) = 98.7030  

Ethernet with 802.1q, 512 byte frame size

8 preamble + 18 header + 4 CRC + 12 gap = 42 bytes/packet

(494 + 22)/(42 + 494) = 95.5224  

Ethernet with 802.1q, 64 byte frame size

8 preamble + 18 header + 4 CRC + 12 gap = 42 bytes/packet

(46 + 22)/(42 + 46) = 72.7273

 

TCP over Ethernet data rates

The following table shows theoretical TCP data rates in Netrounds TCP performance tests.

Protocol

Overhead (bytes)

Theoretical Data Rate (%)

TCP over Ethernet, IPv4

Assuming no header compression

20 IPv4 + 20 TCP + 12 timestamps = 52 bytes/packet

(1500 – 52)/(38 + 1500) = 94.1482

TCP over Ethernet, 802.1q, IPv4

Assuming no header compression

20 IPv4 + 20 TCP + 12 timestamps = 52 bytes/packet

(1500 – 52)/(42 + 1500) = 93.9040

TCP over Ethernet, IPv6

Assuming no header compression

40 IPv6 + 20 TCP + 12 timestamps = 72 bytes/packet

(1500 – 72)/(38 + 1500) = 92.8479

TCP over Ethernet, 802.1q, IPv6

Assuming no header compression

40 IPv6 + 20 TCP + 12 timestamps = 72 bytes/packet

(1500 – 72)/(42 + 1500) = 92.6070

 

UDP over Ethernet data rates

The following table shows theoretical data rates in UDP tests. These are provided as a reference; no such measurements are presented in Netrounds.

Protocol

Overhead (bytes)

Theoretical Data Rate (%)

UDP over Ethernet, IPv4

20 IPv4 + 8 UDP = 28 bytes/packet

 

(1500 – 28)/(38 + 1500) = 95.7087

UDP over Ethernet, 802.1q, IPv4

20 IPv4 + 8 UDP = 28 bytes/packet

 

(1500 – 28)/(42 + 1500) = 95.4604

UDP over Ethernet, IPv6

40 IPv6 + 8 UDP = 48 bytes/packet

 

(1500 – 48)/(38 + 1500) = 94.4083

UDP over Ethernet, 802.1q, IPv6

40 IPv6 + 8 UDP = 48 bytes/packet

 

(1500 – 48)/(42 + 1500) = 94.1634 

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