Test Networks

This document describes the Bitcoin Cash test networks supported by the
BCHN software.

There are currently three test networks that you can access with BCHN:

• testnet3 (historical testnet)
• testnet4
• scalenet
• chipnet

These test network are maintained and supported by the wider community
of protocol developers. They can be accessed by running the software
(daemon, GUI and CLI) with -testnet, -testnet4, -scalenet and
-chipnet arguments, respectively.

Other software clients may have additional test network definitions compiled
into them but these are not currently supported by BCHN and could not be
accessed without further modifications to the software. If you wish BCHN
to access a test network not listed above, please raise a support request.

Below, we give a brief description and an overview table for these networks.

Testnet3

This is the historical testnet in Bitcoin Cash, maintained as a fork from
BTC’s testnet3 since 2017. It has grown substantially in size
(2020/Oct/15: 44GB), in part due to scaling tests that deposited a number
of 32MB blocks, and due to the resulting time to sync a test node from
scratch, has become inconvenient for quick tests.

The historical role is as a test network where application builders can
test their apps against the currently deployed consensus rules (as much
as possible) and at minimal expense without disrupting the main network.

Testnet4

Testnet4 is a testnet3 replacement (starting from a fresh genesis block)
intended to be kept light-weight and quick to sync, in other words free of
big block ‘spam’.

It continues the role of a test network where application builders can
test their apps against most of the currently deployed mainnet consensus
at minimal expense without disrupting the main network.

Testnet4 has a reduced default blocksize to discourage high throughput and
difficulty algorithm settings adjusted to make sure it recovers to be
CPU-mineable quickly after someone has used an ASIC on it.

Scaling tests should use ‘scalenet’ instead (see next section).

Scalenet

Scalenet is intended as a place to test application performance in
high-throughput situations (bigger blocks, more transactions etc).

Scalenet will have a default blocksize limit a few times higher than
mainnet’s limit, to serve as a proving ground for future scaling.

ASIC mining on scalenet will be encouraged and the mining difficulty will
adjust slower to allow accurate exploration of mining strategies.

Every 6 months or so, scalenet’s block 10,000 will be invalidated and a new
block will be checkpointed in its place, clearing out the previous high volume
history and keeping scalenet semi-affordable to synchronize.

Scalenet is intended to target the performance level of a ~$40/month VPS
or a $500 desktop computer for the near future. Any tests that target higher
performance levels are encouraged to do so by forking off of scalenet or
creating their own private testnets or regtest networks.

Chipnet

Chipnet is intended as a place to test against upcoming Cash Improvement
Proposals (CHIPs) which are intended to be activated in the next main network
consensus upgrade.

It therefore deploys these CHIPs (and updates to them) as much in advance as
possible (optimally 6 months ahead of the main network upgrades).

Overview Table for BCHN-supported Test Networks

Attribute/Network
testnet3
testnet4
scalenet
chipnet

Default p2p port
18333
28333
38333
48333

Network magic bytes
0xf4e5f3f4
0xe2b7daaf
0xc3afe1a2
0xe2b7daaf

CashAddr prefix
bchtest
bchtest
bchtest
bchtest

Default excessive block size
32MB
2MB
256MB
2MB

Block Target spacing
10 min
10 min
10 min
10 min

POW limit
2^224
2^224
2^224
2^224

ASERT half-life
1 hour
1 hour
2 days
1 hour

Allow min diff blocks
yes
yes
yes
yes

Require standard txs
no
yes
no
yes

Default consist. chks.
no
no
no
no

Halving interval (blks)
210000
210000
210000
210000

BIP16 height
514
1
1
1

BIP34 height
21111
2
2
2

BIP65 height
581885
3
3
3

BIP66 height
330776
4
4
4

CSV height
770112
5
5
5

UAHF (BCH fork) height
1155875
6
6
6

Nov 13 2017 HF height
1188697
3000
3000
3000

Nov 15 2018 HF height
1267996
4000
4000
4000

Nov 15 2019 HF height
1341711
5000
5000
5000

May 15 2020 HF height
1378460
0 (Note 1)
0 (Note 1)
0 (Note 1)

Nov 15 2020 HF height
1421482
16845
variable (Note 2)
16845

May 15 2021 HF height
1447364
42946
34071
42946

May 15 2022 HF height
1500206
95465
36060
95465

Base58 prefix: pubkey
1, 111
1, 111
1, 111
1, 111

Base58 prefix: script
1, 196
1, 196
1, 196
1, 196

Base58 prefix: seckey
1, 239
1, 239
1, 239
1, 239

Base58 p: ext. pubkey
0x043587cf
0x043587cf
0x043587cf
0x043587cf

Base58 p: ext. seckey
0x04358394
0x04358394
0x04358394
0x04358394

Note 1: set to 0 because historical sigop code has been removed from BCHN
See chainparams.cpp for more detailed comments.

Note 2: scalenet is intended to be periodically reorganized down to a
height of 10000 whose earlier than the November 2020 MTP activation
time. The height at which the Axion upgrade takes effect is thus
variable (it is block 16869 now, but may be different once the
network is reset).

Further references