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diff --git a/doc/reduce-traffic.md b/doc/reduce-traffic.md new file mode 100644 index 0000000000..2d86588eb2 --- /dev/null +++ b/doc/reduce-traffic.md @@ -0,0 +1,38 @@ +Reduce Traffic +============== + +Some node operators need to deal with bandwidth caps imposed by their ISPs. + +By default, bitcoin-core allows up to 125 connections to different peers, 8 of +which are outbound. You can therefore, have at most 117 inbound connections. + +The default settings can result in relatively significant traffic consumption. + +Ways to reduce traffic: + +## 1. Use `-maxuploadtarget=<MiB per day>` + +A major component of the traffic is caused by serving historic blocks to other nodes +during the initial blocks download phase (syncing up a new node). +This option can be specified in MiB per day and is turned off by default. +This is *not* a hard limit; only a threshold to minimize the outbound +traffic. When the limit is about to be reached, the uploaded data is cut by no +longer serving historic blocks (blocks older than one week). +Keep in mind that new nodes require other nodes that are willing to serve +historic blocks. **The recommended minimum is 144 blocks per day (max. 144MB +per day)** + +Whitelisted peers will never be disconnected, although their traffic counts for +calculating the target. + +## 2. Disable "listening" (`-listen=0`) + +Disabling listening will result in fewer nodes connected (remember the maximum of 8 +outbound peers). Fewer nodes will result in less traffic usage as you are relaying +blocks and transactions to fewer nodes. + +## 3. Reduce maximum connections (`-maxconnections=<num>`) + +Reducing the maximum connected nodes to a minimum could be desirable if traffic +limits are tiny. Keep in mind that bitcoin's trustless model works best if you are +connected to a handful of nodes. |