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Improve discovery docs (#917)
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* Improve discovery docs

Signed-off-by: Alexandra Tran <[email protected]>

* integrate reviewer feedback

Signed-off-by: Alexandra Tran <[email protected]>
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alexandratran authored Jan 12, 2022
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4 changes: 2 additions & 2 deletions docs/HowTo/Find-and-Connect/Bootnodes.md
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# Bootnodes

Using Bootnodes is a method for initially discovering peers. Bootnodes are regular nodes used to
discover other nodes.
You can use bootnodes to initially discover peers.
Bootnodes are regular nodes used to discover other nodes.

!!! tip

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99 changes: 58 additions & 41 deletions docs/HowTo/Find-and-Connect/Managing-Peers.md
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description: Managing Hyperledger Besu peers
---

# Managing peers
# Manage peers

## Limiting peers
Hyperledger Besu peer-to-peer (P2P) discovery happens periodically based on the number of peers in a network and the
node's [peer limit](#limit-peers).

Limiting peers reduces the bandwidth used by Hyperledger Besu. Limiting peers also reduces the CPU
time and disk access used to manage and respond to peers.
The frequency of discovery isn't configurable, but you can [limit remote connections](#limit-remote-connections) in
public networks and [randomly prioritize connections](../../Reference/CLI/CLI-Syntax.md#random-peer-priority-enabled)
in small, stable networks.

!!! info

You can use [`admin_addPeer`](../../Reference/API-Methods.md#admin_addpeer) to attempt a specific connection, but
this isn't P2P discovery.

We recommend [using bootnodes](Bootnodes.md) to initially discover peers.

## Limit peers

You can limit peers to reduce the bandwidth, CPU time, and disk access Besu uses to manage and respond to peers.

To reduce the maximum number of peers, use the
[`--max-peers`](../../Reference/CLI/CLI-Syntax.md#max-peers) option. The default is 25.

## No discovery
## Limit remote connections

To disable P2P discovery, use the
[`--discovery-enabled`](../../Reference/CLI/CLI-Syntax.md#discovery-enabled) option.
Prevent eclipse attacks when using [`--sync-mode`](../../Reference/CLI/CLI-Syntax.md#sync-mode) and
[`--fast-sync-min-peers`](../../Reference/CLI/CLI-Syntax.md#fast-sync-min-peers) on public networks by enabling the
[remote connection limits](../../Reference/CLI/CLI-Syntax.md#remote-connections-limit-enabled).

With discovery disabled, peers that have already discovered or are otherwise configured to connect
to the local node (for example, using
[`admin_addPeer`](../../Reference/API-Methods.md#admin_addpeer)) can open connections.
[Static nodes](Static-Nodes.md) can also open connections.
In private and permissioned networks with only trusted peers, enabling the remote connection limits is
unnecessary and might adversely affect the speed at which nodes can join the network.
Limiting remote connections can cause a closed group of peers to form when the number of nodes in the network is
slightly higher than [`--max-peers`](../../Reference/CLI/CLI-Syntax.md#max-peers).
The nodes in this closed group are all connected to each other and can't accept more connections.

!!! tip

You can use [`--random-peer-priority-enabled`](../../Reference/CLI/CLI-Syntax.md#random-peer-priority-enabled) to
help prevent closed groups of peers in small, stable networks.

## Monitoring peer connections
## Monitor peer connections

JSON-RPC API methods to monitor peer connections include:

* [`net_peerCount`](../../Reference/API-Methods.md#net_peercount)
* [`admin_peers`](../../Reference/API-Methods.md#admin_peers)
* [`net_peerCount`](../../Reference/API-Methods.md#net_peercount).
* [`admin_peers`](../../Reference/API-Methods.md#admin_peers).
* [`debug_metrics`](../../Reference/API-Methods.md#debug_metrics).

Each peer entry returned by [`admin_peers`](../../Reference/API-Methods.md#admin_peers) includes a
`protocols` section. Use the information in the `protocols` section to:

* Determine health of peers. For example, an external process could use [`admin_peers`](../../Reference/API-Methods.md#admin_peers)
and [`admin_removePeer`](../../Reference/API-Methods.md#admin_removepeer) to disconnect from peers that
are stalled at a single difficulty for an extended period of time.
* Determine the health of peers.
For example, an external process can use [`admin_peers`](../../Reference/API-Methods.md#admin_peers) and
[`admin_removePeer`](../../Reference/API-Methods.md#admin_removepeer) to disconnect from peers that are stalled at a
single difficulty for an extended period of time.

* Monitor node health. For example, if peers are reporting increasing difficulties but node
is stuck at the same block number, the node may be on a different fork to most peers.
* Monitor node health.
For example, if peers report increasing difficulties but the node is stuck at the same block number, the node may be
on a different fork to most peers.

* Determine which protocol level peers are communicating with. For example, to see if `"version": 65`
is being used to reduce transaction sharing traffic.
* Determine which protocol level peers are communicating with.
For example, you can see if `"version": 65` is being used to reduce transaction sharing traffic.

## Node connections
## List node connections

The default logging configuration does not list node connection and disconnection messages.
The default logging configuration doesn't list node connection and disconnection messages.
To enable listing them, set the [`--logging`](../../Reference/CLI/CLI-Syntax.md#logging) option to `DEBUG`.
For more verbosity, set the option to `TRACE`.

To enable listing of node connection and disconnection messages, specify the
[`--logging`](../../Reference/CLI/CLI-Syntax.md#logging) option `--logging=DEBUG`. For more
verbosity, specify `--logging=TRACE`.

The console logs connection and disconnection events when the log level is `DEBUG` or higher. If
the message `Successfully accepted connection from ...` displays, connections are getting through
the firewalls.
The console logs connection and disconnection events when the log level is `DEBUG` or higher.
If the message `Successfully accepted connection from ...` displays, connections are getting through the firewalls.

!!! example "Sample log output"

`2018-10-16 12:37:35.479-04:00 | nioEventLoopGroup-3-1 | INFO | NettyP2PNetwork | Successfully accepted connection from 0xa979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c`
```bash
2018-10-16 12:37:35.479-04:00 | nioEventLoopGroup-3-1 | INFO | NettyP2PNetwork | Successfully accepted connection from 0xa979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c
```

## Limiting remote connections
## Disable discovery

In private and permissioned networks with a level of trust between peers, enabling the
[remote connection limits](../../Reference/CLI/CLI-Syntax.md#remote-connections-limit-enabled)
is unnecessary and might adversely affect the speed at which nodes can join the network.
Limiting remote connections may cause a clique of nodes to form when the number of nodes in the network is slightly
higher than [`--max-peers`](../../Reference/CLI/CLI-Syntax.md#max-peers).
The nodes in this clique are all connected to each other and cannot accept more connections.
To disable P2P discovery, set the
[`--discovery-enabled`](../../Reference/CLI/CLI-Syntax.md#discovery-enabled) option to `false`.

In public networks, enabling the remote connections limit is necessary to prevent eclipse attacks, especially when
using [`--sync-mode`](../../Reference/CLI/CLI-Syntax.md#sync-mode) and
[`--fast-sync-min-peers`](../../Reference/CLI/CLI-Syntax.md#fast-sync-min-peers).
With discovery disabled, peers can't open connections with the node unless they were previously discovered or manually
peered (for example, using [`admin_addPeer`](../../Reference/API-Methods.md#admin_addpeer)).
[Static nodes](Static-Nodes.md) can also open connections.
7 changes: 4 additions & 3 deletions docs/Reference/CLI/CLI-Syntax.md
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```

Allows for incoming connections to be prioritized randomly. Enable in small, stable networks to prevent
impenetrable peer groups forming. The default is `false`.
closed groups of peers forming. The default is `false`.

### `remote-connections-limit-enabled`

Expand Down Expand Up @@ -2390,8 +2390,9 @@ impenetrable peer groups forming. The default is `false`.
remote-connections-limit-enabled=false
```

Enables or disables limiting the percentage of remote P2P connections initiated by peers. The
default is true.
Enables or disables using the [`--remote-connections-max-percentage`](#remote-connections-max-percentage) option to
limit the percentage of remote P2P connections initiated by peers.
The default is `true`.

!!! tip

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