RelayBandwidthBurst

Hi!

Torrc, How many percent higher should RelayBandwidthBurst be against RelayBandwidthRate?

(25%, 50%, 75% or 100%)

It depends on how you want to shape your traffic, and what bandwidth is available to you. All of the ranges you described are reasonable choices, and much higher percentages can also be reasonable.

If you make the Burst much much higher than the Rate, then you will enforce the Rate as a long term average, yet allow your relay to use quite a bit more than that if it isn’t hitting that long term rate. For example, if you have a super fast connection, but your ISP gives you a cap on the total number of bytes you can send/receive in a month, you might pick your Rate to be whatever average would sum up to that cap, but pick the Burst to be something big like 1GByte. That way the Rate only kicks in if you have handled a lot of traffic recently, and if the traffic subsides, then the Burst starts building back up again.

The only situation where you should choose a Burst that is close to your Rate is when they are both actually reflecting the limit of your network connection. That is, if your network connection can only do 100mbit/s, and you are setting the Rate to something like 95mbit/s, then it doesn’t make sense to set the burst any higher than 100mbit. That is, it is better for the network for you to rate-limit your relay to just under the speed of your actual network, rather than relying on TCP’s pushback to slow things down.

The underlying mechanism for how Rate and Burst work is called a Token Bucket: Token bucket - Wikipedia

For other answers to this question, see

and

Thanks for running a relay!

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