Managing Peers

Limiting Peers

Limiting peers reduces the bandwidth used by Pantheon. It also reduces the CPU time and disk access used to manage and respond to peers.

Use the --max-peers command line option to reduce the maximum number of peers. The default is 25.

No Discovery

The --discovery-enabled command line option can be used to disable P2P peer discovery. Set this option to false if you are running a test node or a network with static nodes.

Static Nodes

Static nodes are configured nodes that remain connected rather than nodes connected through P2P discovery. Static nodes attempt to maintain connectivity. If a connection goes down to a static node, the node attempts to reconnect every 60 seconds.

To configure a network of static nodes:

List enode URLs of the nodes in the static-nodes.json file.
Save the static-nodes.json file in the data directory of each node.
Start Pantheon with discovery disabled using --discovery-enabled=false.

To modify the static peers at run time, use the admin_addPeer and admin_removePeer JSON-RPC API methods.

!!! note Runtime modifications of static nodes are not persisted between runs. The static-nodes.json file is not updated by admin_addPeer and admin_removePeer methods.

Nodes outside of the static nodes are not prevented from connecting.  To prevent nodes from connecting,
use [Permissioning](../../Permissions/Permissioning.md).

!!! caution If the added peer does not appear in the peer list (returned by admin_peers), check the supplied enode URL is correct, the node is running, the node is listening for TCP connections on the endpoint, and has not reached the maximum number of peers.

static-nodes.json File

The static-nodes.json file must be located in the data directory (specified by --data-path) and contain a JSON array of enode URLs.

!!! example json [ "enode://cea71cb65a471037e01508cebcc178f176f9d5267bf29507ea1f6431eb6a5dc67d086dc8dc54358a72299dab1161febc5d7af49d1609c69b42b5e54544145d4f@127.0.0.1:30303", "enode://ca05e940488614402705a6b6836288ea902169ecc67a89e1bd5ef94bc0d1933f20be16bc881ffb4be59f521afa8718fc26eec2b0e90f2cd0f44f99bc8103e60f@127.0.0.1:30304" ]

!!! note Each node has a static-nodes.json file. We recommend each node in the network has the same static-nodes.json file.

Monitoring Peer Connections

JSON-RPC API methods to monitor peer connections include:

Node Connections

The default logging configuration does not list node connection and disconnection messages.

To enable listing of node connection and disconnection messages, specify the --logging command line 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 Successfully accepted connection from ... is displayed, connections are getting through the firewalls.

!!! example "Example log output" 2018-10-16 12:37:35.479-04:00 | nioEventLoopGroup-3-1 | INFO | NettyP2PNetwork | Successfully accepted connection from 0xa979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c

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