Converting packet loss percentage to BER

Started by Wendell

Wendell

Converting packet loss percentage to BER   15 December 2017, 12:40

I am trying to simulate a "dirty" t1 line with worst case scenario of up to 600 ms delay round trip and BER of 10e-5. Question is how do I convert the packet loss percentage to BER?
SoftPerfect Support forum - Ann avatar image
Ann

Re: Converting packet loss percentage to BER   15 December 2017, 13:27

As far as I understand, BER is the likelihood bit errors, say when a 0 becomes 1 or vice versa, so I would recommend to use the Corruption tab, where you can specify the percentage of packets to be corrupted. The software will flip a random bit in a packet to simulate a transmission error or a faulty network device.

Regarding the conversion, it is not possible to convert exactly. The BER of 10e-5 suggests that 1 bit in 10000 is damaged, which is 1 bit in every 1250 bytes. With the assumption that an average packet is 1500 bytes in size (MTU), this implies that 100% of packets are corrupted.

While you can set 100% packets to be corrupted, most likely no communication will be possible or it will be extremely slow with retransmissions. On the other hand, if your packets are smaller, say 125 bytes, the corruption rate should be much lower, 10%.

I guess it's best if we add a BER setting into the software directly, so the bit error rate could be expressed not only with percentage of packets, but also with BER specified directly. This may take a few days.
SoftPerfect Support forum - Andrew avatar image

Re: Converting packet loss percentage to BER   19 December 2017, 16:14

We have added two new ways to specify bit errors in corrupted packet emulation:
  • Bit Error Rate: the number of bit errors per unit of time, for example you can choose 2 bits to be corrupted per minute.
  • Bit Error Ratio: the number of bit errors divided by the total number of transferred bits. For example, a ratio of 10e-7 or 0.000001 means 1 bit in 1000000 is to be corrupted.

You can enter your BER value directly in the newly released version 1.7.7, which can be downloaded from the home page.

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