From laurentmt145 at gmail.com  Fri Apr 15 12:20:31 2016
From: laurentmt145 at gmail.com (laurentmt)
Date: Fri, 15 Apr 2016 14:20:31 +0200
Subject: [Lightning-dev] Fwd: Re:  Routing & Beacons
In-Reply-To: <570E333F.8030401@gmail.com>
References: <570E333F.8030401@gmail.com>
Message-ID: <5710DC8F.70902@gmail.com>

Hi Rusty,

If I'm correct, it means that on a given period all payments go through
the selected beacons nodes ?

I ask this because some protocols like the pulse protocol are also based
on beacons to update the routing tables but they don't require that all
"messages" go through the beacons. "Messages" go through the first
common ancestor of source and target in the spanning tree associated to
the selected beacon.

The main drawback with this approach is that the source doesn't know the
route beforehand... The main advantage is that it puts less "pressure"
on the beacons.


Another question: have you already decided on an update strategy for the
routing tables?

As I understand the problem, there's 2 variables which determine the
best route:

- capacity of channels at time t (max number of bitcoins I can transfer
through a given channel). It determines if a route can be used to
transfer the amount.

- fees charged by nodes. It determines the best route.

Capacity is likely the most dynamic of the two variables. Do you
consider capacity as an information stored in the routing tables (but it
may be very challenging to keep tables up to date) or is it checked "in
live" when the payment is propagated ?

laurent



Le 13/04/2016 02:40, Rusty Russell a ?crit :
> laurentmt <laurentmt145 at gmail.com> writes:
>> Hi there,
>>
>> Just a LN noob here. I'm intrigued by the idea of routing based on
>> beacons. Is it somewhat similar to the Pulse Protocol
>> (http://www.cs.jhu.edu/~dholmer/600.647/papers/pulse_infrastructure_access.pdf)
>> with a periodic computation of spanning trees rooted at beacons nodes ?
> 
> Hi Laurent!
> 
>         There are several ways to do routing via a known set of
> landmarks.  Since each node is interested in the cheapest route to and
> from each beacon, that's pretty easy to propagate (simply always
> broadcast the best route you know about).
> 
>         Of course, if rates are expressed as "base + per-satoshi-amount"
> then "cheapest" depends on the amount, so some heuristics will be
> required.
> 
> Cheers,
> Rusty.
>