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From: Sjors Provoost <sjors@sprovoost.nl>
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Subject: Re: [bitcoindev] Does anyone still need testnet3?
Date: Tue, 1 Apr 2025 11:06:05 +0200
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Cc: Sanket Kanjalkar <sanket1729@gmail.com>
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Hi Sanket,

I've heard before from some lightning folks that migrating to testnet4 pres=
ents a chicken-egg problem.

If we were to start rotating test networks a frequency of e.g. once every t=
hree years, this would become a recurring problem.

Lightning seems to be a special case because it relies heavily on interoper=
ability, and so any move has to be coordinated between multiple parties eac=
h with their own priorities.

At the same time Lightning software often needs the latest and greatest Bit=
coin Core version e.g. for its new policy features. So sticking to v29 back=
-ports isn't a long term viable option.


I think it's worth considering for the lightning industry to organize a cus=
tom signet, either a 1-of-N with keys distributed among the current players=
, or unsigned proof-of-work based (more hassle, but future new players may =
feel more comfortable joining). Such a network can be kept online definitel=
y and its replacement can be more easily coordinated. Another advantage is =
that soft fork proposals can be tested, similar to how Inquisition does tha=
t on the default signet, but at a pace that matches Bolt spec work.

- Sjors

> Op 31 mrt 2025, om 23:15 heeft Sanket Kanjalkar <sanket1729@gmail.com> he=
t volgende geschreven:
>=20
> Hi Sjors,=20
> Thanks for asking. Block/Cashapp relies on testnet3 and can't migrate to =
testnet4 mostly because of lack of lightning LND peers.
> I don't think there are any LND Lightning peers on testnet4. We (Block/Ca=
shapp lightning) use LDK for Lightning, but most of our peers run LND. LND =
support for testnet4 was just merged <https://github.com/lightningnetwork/l=
nd/pull/9620>, so it=E2=80=99ll likely take time for the LND community to u=
pdate node infrastructure.
> We want to catch peering, business logic and lightning implementations in=
teroperability issues in testnet. Even though LDK supports testnet4, switch=
ing now isn=E2=80=99t viable for us until our mainnet LND peers migrate.=20
>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=
=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; -webkit-nbsp-mod=
e: space; line-break: after-white-space;">Hi Sanket,<div><br></div><div>I'v=
e heard before from some lightning folks that migrating to testnet4 present=
s a chicken-egg problem.</div><div><br></div><div>If we were to start rotat=
ing test networks a frequency of e.g. once every three years, this would be=
come a recurring problem.</div><div><br></div><div>Lightning seems to be a =
special case because it relies heavily on interoperability, and so any move=
 has to be coordinated between multiple parties each with their own priorit=
ies.</div><div><br></div><div>At the same time Lightning software often nee=
ds the latest and greatest Bitcoin Core version e.g. for its new policy fea=
tures. So sticking to v29 back-ports isn't a long term viable option.</div>=
<div><br></div><div><br></div><div>I think it's worth considering for the l=
ightning industry to organize a custom signet, either a 1-of-N with keys di=
stributed among the current players, or unsigned proof-of-work based (more =
hassle, but future new players may feel more comfortable joining). Such a n=
etwork can be kept online definitely and its replacement can be more easily=
 coordinated. Another advantage is that soft fork proposals can be tested, =
similar to how Inquisition does that on the default signet, but at a pace t=
hat matches Bolt spec work.</div><div><br></div><div>- Sjors</div><div><br>=
</div><div><div><blockquote type=3D"cite"><div>Op 31 mrt 2025, om 23:15 hee=
ft Sanket Kanjalkar &lt;sanket1729@gmail.com&gt; het volgende geschreven:</=
div><br class=3D"Apple-interchange-newline"><div><div dir=3D"ltr"><div>Hi S=
jors,&nbsp;<br><p class=3D"gmail-">Thanks for asking. Block/Cashapp relies =
on testnet3 and can't migrate to testnet4 mostly because of lack of lightni=
ng LND peers.<br>I don't think there are any LND Lightning peers&nbsp;on te=
stnet4. We (Block/Cashapp lightning) use&nbsp;LDK for Lightning, but most o=
f our peers run LND. LND support for testnet4 was just <a href=3D"https://g=
ithub.com/lightningnetwork/lnd/pull/9620">merged</a>, so it=E2=80=99ll like=
ly take time for the LND community to update node infrastructure.<br>We wan=
t to catch peering, business logic and lightning implementations interopera=
bility issues in testnet. Even though LDK supports testnet4, switching now =
isn=E2=80=99t viable for us&nbsp;until our mainnet LND peers migrate.&nbsp;=
</p></div></div></div></blockquote></div><br></div></body></html>

<p></p>

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