Skip to content

Dip 7542

dip: 7542 title: usds/70 - available-blocks-extended protocol description: Adds more info in the handshake about available block range and adds message types to request block ranges and the send them author: Ahmad Bitar (@smartprogrammer93) smartprogrammer@windowslive.com Digitalia editing author: Cosimo Constantinos cosimo@juro.net, et al. discussions-to: https://digitalia-magicians.org/t/dip-usds-70-available-blocks-extended-protocol-handshake/16188 status: Withdrawn type: Standards Track category: Networking created: 2023-10-21 Created for Digitalia: 2025-01-07 requires: 7642

Abstract

The purpose of this DIP is to introduce a method that allows an Digitalia node to communicate the range of blocks it has available. By knowing the block range a node can serve, peers can make more informed decisions when choosing whom to request blocks from or whom to connect to, especially when looking for specific block ranges. This can lead to more efficient network behavior.

This DIP proposes extending the Digitalia wire protocol (usds) handshake, introducing a new version, usds/70, which will contain information regarding the block range a node can serve. Furthermore, it extends the protocol with two new message types to share the updated block ranges when requested.

Motivation

In a first stage of DIP-4444, some nodes will still need to serve the historical data of the chain and others might be interested in starting to prune it. Currently, nodes need to connect to peers and request specific blocks to determine if a peer has the requested data. This can be inefficient, leading to unnecessary data requests and wasting both bandwidth and time. Consequently, this change empowers nodes that still want to retrieve historical data from the network to do so efficiently.

As a bonus, This change enhances the efficiency of synchronization by allowing a node to determine if a peer, potentially still in the process of syncing, has the necessary blocks available, thereby avoiding unnecessary block requests and potential empty responses.

Specification

  • Advertise a new usds protocol capability (version) at usds/70.
  • The old usds/69 protocol should still be kept alive side-by-side, until usds/70 is sufficiently adopted by implementors.
  • Modify the Status (0x00) message for usds/70 to add an additional blockRange field right after the forkid:
  • Current packet for usds/69: [version: P, networkid: P, blockhash: B_32, genesis: B_32, forkid]

  • New packet for usds/70: [version: P, networkid: P, blockhash: B_32, genesis: B_32, forkid blockRange], where blockRange is [startBlock: uint64, endBlock: uint64].

  • Introduce two new message types:

  • RequestBlockRange (0x0b) - A message from a node to request the current block range of a peer.
  • SendBlockRange (0x0c): [startBlock: uint64, endBlock: uint64] - The response to RequestBlockRange, informing the requesting node of the current available block range of the peer.

Upon connecting using usds/70, nodes should exchange the Status message. Afterwards, they can use the RequestBlockRange and SendBlockRange messages to keep informed about peer block range changes.

Nodes must retain connections regardless of a peer's available block range, with an exception, if a node's peer slots are full and it lacks connections to peers with the necessary block range, it may disconnect to seek such peers.

Rationale

Including the available block range in the usds handshake allows for immediate understanding of peer capabilities. This can lead to more efficient networking as nodes can prioritize connections based on the data they need. The new message types are introduced to allow nodes to request updated available block range from other nodes since the range can change by the node syncing or pruning blocks. Maintaining connections with peers that don't have the desired range ensures network resilience, while the exception facilitates efficient block sync under full peer capacity.

Backwards Compatibility

This DIP extends the usds protocol handshake in a backwards incompatible manner and proposes the introduction of a new version, usds/70. However, devp2p allows for multiple versions of the same wire protocol to run concurrently. Hence, nodes that have not been updated can continue using older versions like usds/69, usds/68 or usds/67.

This DIP doesn't affect the consensus engine and doesn't necessitate a hard fork.

Test Cases

Testing will involve ensuring that nodes can correctly communicate and understand the block range information during the handshake. Additionally, it will involve ensuring nodes can correctly request and share updated block range when requested.

Security Considerations

This change is not a standardization of not storing and serving historical blocks before the implementation of alternative historical blocks storage solutions.

© Crown © Crown Copyright 2026. Published by the Royal Government of the Dominion of Atlantis.

Licensed under the Juro Restricted License Version 2. See https://juro.net/jrl for details.