lightning/doc/lightning-getroute.7

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.\"     Title: lightning-getroute
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 02/19/2018
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "LIGHTNING\-GETROUTE" "7" "02/19/2018" "\ \&" "\ \&"
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.SH "NAME"
lightning-getroute \- Protocol for routing a payment (low\-level)\&.
.SH "SYNOPSIS"
.sp
\fBgetroute\fR \fIid\fR \fImsatoshi\fR \fIriskfactor\fR [\fIcltv\fR] [\fIfuzzpercent\fR] [\fIseed\fR]
.SH "DESCRIPTION"
.sp
The \fBgetroute\fR RPC command attempts to find the best route for the payment of \fImsatoshi\fR to lightning node \fIid\fR, such that the payment will arrive at \fIid\fR with \fIcltv\fR\-blocks to spare (default 9)\&.
.sp
There are two considerations for how good a route is: how low the fees are, and how long your payment will get stuck if a node goes down during the process\&. The \fIriskfactor\fR floating\-point field controls this tradeoff; it is the annual cost of your funds being stuck (as a percentage), multiplied by the percentage chance of each node failing\&.
.sp
For example, if you thought there was a 1% chance that a node would fail, and it would cost you 20% per annum if that happened, \fIriskfactor\fR would be 20\&.
.sp
If you didn\(cqt care about risk, \fIriskfactor\fR would be zero\&.
.sp
The \fIfuzzpercent\fR is a floating\-point number, between 0\&.0 to 100\&.0, unit of percent\&. The \fIfuzzpercent\fR is used to distort computed fees along each channel, to provide some randomization to the route generated\&. 0\&.0 means the exact fee of that channel is used, while 100\&.0 means the fee used might be from 0 to twice the actual fee\&. The default is 5\&.0, or up to 5% fee distortion\&.
.sp
The \fIseed\fR is a string whose bytes are used to seed the RNG for the route randomization\&. If not specified, a random string is used\&.
.SH "RISKFACTOR EFFECT ON ROUTING"
.sp
The risk factor is treated as if it were an additional fee on the route, for the purposes of comparing routes\&.
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The formula used is the following approximation:
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.if n \{\
.RS 4
.\}
.nf
hop\-risk = num\-hops x per\-hop\-risk
timeout\-cost = blocks\-timeout x per\-block\-cost
risk\-fee = amount x hop\-risk x timeout\-cost
.fi
.if n \{\
.RE
.\}
.sp
We are given a \fIriskfactor\fR; expressed as two multiplied percentages is the same as fractions multiplied by 10000\&. There are 52596 blocks per year, thus \fIper\-block\-cost\fR x \fIper\-hop\-risk\fR is riskfactor\*(Aq divided by 5,259,600,000\&.
.sp
The final result is:
.sp
.if n \{\
.RS 4
.\}
.nf
risk\-fee = amount x num\-hops x blocks\-timeout x riskfactor / 5259600000
.fi
.if n \{\
.RE
.\}
.sp
Here are the risk fees as a percentage of the amount sent, using various parameters\&. For comparison with actual fees, we assume nodes charge 0\&.05%:
.TS
allbox tab(:);
ltB ltB ltB ltB ltB.
T{
Riskfactor
T}:T{
Nodes
T}:T{
Delay per node
T}:T{
Risk Fee %
T}:T{
Route fee %
T}
.T&
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt
lt lt lt lt lt.
T{
.sp
0\&.001
T}:T{
.sp
5
T}:T{
.sp
6
T}:T{
.sp
0
T}:T{
.sp
0\&.25
T}
T{
.sp
1
T}:T{
.sp
5
T}:T{
.sp
6
T}:T{
.sp
0
T}:T{
.sp
0\&.25
T}
T{
.sp
1000
T}:T{
.sp
5
T}:T{
.sp
6
T}:T{
.sp
0\&.0029
T}:T{
.sp
0\&.25
T}
T{
.sp
0\&.001
T}:T{
.sp
10
T}:T{
.sp
72
T}:T{
.sp
0
T}:T{
.sp
0\&.5
T}
T{
.sp
1
T}:T{
.sp
10
T}:T{
.sp
72
T}:T{
.sp
0\&.0001
T}:T{
.sp
0\&.5
T}
T{
.sp
1000
T}:T{
.sp
10
T}:T{
.sp
72
T}:T{
.sp
0\&.1369
T}:T{
.sp
0\&.5
T}
T{
.sp
0\&.001
T}:T{
.sp
20
T}:T{
.sp
1008
T}:T{
.sp
0
T}:T{
.sp
1\&.0
T}
T{
.sp
1
T}:T{
.sp
20
T}:T{
.sp
1008
T}:T{
.sp
0\&.0077
T}:T{
.sp
1\&.0
T}
T{
.sp
1000
T}:T{
.sp
20
T}:T{
.sp
1008
T}:T{
.sp
7\&.6660
T}:T{
.sp
1\&.0
T}
.TE
.sp 1
.SH "RECOMMENDED RISKFACTOR VALUES"
.sp
0\&.001 is a value for tie\-breaking in favor of shorter routes, but not really costing in any risk\&.
.sp
1 is a conservative value for a stable lightning network with very few failures\&.
.sp
1000 is an aggressive value for trying to minimize timeouts at all costs\&.
.SH "RETURN VALUE"
.sp
On success, a "route" array is returned\&. Each array element contains
.sp
timeout for the payment failure, in blocks\&.
.SH "AUTHOR"
.sp
Rusty Russell <rusty@rustcorp\&.com\&.au> is mainly responsible\&.
.SH "SEE ALSO"
.sp
lightning\-pay(7), lightning\-sendpay(7)\&.
.SH "RESOURCES"
.sp
Main web site: https://github\&.com/ElementsProject/lightning