Can you reduce RTT by increasing the bandwidth on a link

latencyprotocol-theory

Does increasing the bandwidth on a link from, let's say, 1mb to 30mb reduce the RTT?

I have found one answer saying no. Can someone please explain?

Also, what are the best mechanisms to reduce RTT?

Best Answer

Does increasing the bandwidth on a link from lets say 1mb to 30mb reduce the RTT?

In short, yes; you are changing serialization delay; at 1Mbps the serialization delay is non-trivial.

Compare the serialization delay for a 1500 Byte packet at 1Mbps and 30Mbps:

1500 Bytes * 8 bits/Byte / 1,000,000 bits/second    = 12 milliseconds (at 1Mbps)
1500 Bytes * 8 bits/Byte / 30,000,000 bits/second   = 0.4 milliseconds (at 30Mbps)

Remember also that those are unidirectional numbers; you should double them when considering RTT. Whether you care about 11.6 milliseconds difference in each direction at 1500 bytes is another question, but strictly speaking you can influence RTT with link speed.

Related Topic