132 lines
4.4 KiB
Markdown
132 lines
4.4 KiB
Markdown
ETH 2.0 Networking Spec - Libp2p standard protocols
|
|
===
|
|
|
|
# Abstract
|
|
|
|
Ethereum 2.0 clients plan to use the libp2p protocol networking stack for
|
|
mainnet release. This document aims to standardize the libp2p client protocols,
|
|
configuration and messaging formats.
|
|
|
|
# Libp2p Protocols
|
|
|
|
## Gossipsub
|
|
|
|
#### Protocol id: `/meshsub/1.0.0`
|
|
|
|
*Note: Parameters listed here are subject to a large-scale network feasibility
|
|
study*
|
|
|
|
The [Gossipsub](https://github.com/libp2p/specs/tree/master/pubsub/gossipsub)
|
|
protocol will be used for block and attestation propagation across the
|
|
network.
|
|
|
|
### Configuration Parameters
|
|
|
|
Gossipsub has a number of internal configuration parameters which directly
|
|
effect the network performance. Clients can implement independently, however
|
|
we aim to standardize these across clients to optimize the gossip network for
|
|
propagation times and message duplication. Current network-related defaults are:
|
|
|
|
```
|
|
(
|
|
// The target number of peers in the overlay mesh network (D in the libp2p specs).
|
|
mesh_size: 6
|
|
// The minimum number of peers in the mesh network before adding more (D_lo in the libp2p specs).
|
|
mesh_lo: 4
|
|
// The maximum number of peers in the mesh network before removing some (D_high in the libp2p sepcs).
|
|
mesh_high: 12
|
|
// The number of peers to gossip to during a heartbeat (D_lazy in the libp2p sepcs).
|
|
gossip_lazy: 6 // defaults to `mesh_size`
|
|
// Time to live for fanout peers (seconds).
|
|
fanout_ttl: 60
|
|
// The number of heartbeats to gossip about.
|
|
gossip_history: 3
|
|
// Time between each heartbeat (seconds).
|
|
heartbeat_interval: 1
|
|
)
|
|
```
|
|
|
|
### Topics
|
|
|
|
*The Go and Js implementations use string topics - This is likely to be
|
|
updated to topic hashes in later versions - https://github.com/libp2p/rust-libp2p/issues/473*
|
|
|
|
For Eth2.0 clients, topics will be sent as `SHA2-256` hashes of the topic string.
|
|
|
|
There is one dedicated topic for propagating beacon blocks and aggregated
|
|
attestations across the network. This topic will have the string
|
|
`beacon_chain`. Each shard will have it's own topic allowing relevant parties
|
|
to subscribe to in order to receive local shard attestations. The shard topics are
|
|
prefixed with `shard` followed by the number of the shard. For example,
|
|
messages relating to shard 10, will have the topic string `shard10`.
|
|
|
|
### Messages
|
|
|
|
Messages sent across gossipsub are fixed-size length-prefixed byte arrays.
|
|
Each message has a maximum size of 512KB (estimated from expected largest uncompressed
|
|
block size).
|
|
|
|
The byte array is prefixed with a unsigned 64 bit length number encoded as an
|
|
`unsigned varint` (https://github.com/multiformats/unsigned-varint). Gossipsub messages therefore take the form:
|
|
```
|
|
+--------------------------+
|
|
| message length |
|
|
+--------------------------+
|
|
| |
|
|
| body (<1M) |
|
|
| |
|
|
+--------------------------+
|
|
```
|
|
|
|
The body of the message is an SSZ-encoded object representing either a
|
|
beacon block or attestation. The type of objected is determined via a prefixed
|
|
nibble. Currently there are two objects that are sent across the gossip
|
|
network. They are (with their corresponding nibble specification):
|
|
|
|
- `0x1`: Beacon block
|
|
- `0x2`: Attestation
|
|
|
|
The body therefore takes the form:
|
|
```
|
|
+--------------------------+
|
|
| type nibble |
|
|
+--------------------------+
|
|
| |
|
|
| SSZ-encoded object |
|
|
| |
|
|
+--------------------------+
|
|
```
|
|
|
|
## Eth-2 RPC
|
|
|
|
#### Protocol Id: `/eth/serenity/beacon/rpc/1`
|
|
|
|
The [RPC Interface](./rpc-interface.md) is specified in this repository.
|
|
|
|
|
|
## Identify
|
|
|
|
#### Protocol Id: `/ipfs/id/1.0.0` (to be updated to `/p2p/id/1.0.0`)
|
|
|
|
The Identify protocol (defined in go - [identify-go](https://github.com/ipfs/go-ipfs/blob/master/core/commands/id.go) and rust [rust-identify](https://github.com/libp2p/rust-libp2p/blob/master/protocols/identify/src/lib.rs))
|
|
allows a node A to query another node B which information B knows about A. This also includes the addresses B is listening on.
|
|
|
|
This protocol allows nodes to discover addresses of other nodes to be added to
|
|
peer discovery. It further allows nodes to determine the capabilities of all it's connected
|
|
peers.
|
|
|
|
### Configuration Parameters
|
|
|
|
The protocol has two configurable parameters, which can be used to identify the
|
|
type of connecting node. Suggested format:
|
|
```
|
|
version: `/eth/serenity/1.0.0`
|
|
user_agent: <client name and version>
|
|
```
|
|
|
|
## Discovery
|
|
|
|
#### Protocol Id: `/eth/serenity/disc/1.0.0`
|
|
|
|
The discovery protocol to be determined.
|