DoubleZero introduces Multicast Support: smarter, faster data delivery for distributed systems
Today, DoubleZero client software v0.2.2 was released to testnet introducing the user interface for interacting with multicast on the DoubleZero network. This release sets the stage for development teams to begin proof-of-concept and pilot testing the integration of multicast-based transports in their applications. For validators, this replaces the need to send separate packets to each peer, reducing redundant transmissions and overall bandwidth usage.
Background
Multicast efficiently delivers data from a single source to multiple recipients by sending the packet once and relying on application-specific integrated circuits (ASICs) within network switches to handle replication, rather than placing that burden on the source computer. Multicast is generally only available in privately-owned networks under the control of a single administrative entity because despite the best efforts of standards bodies such as the Internet Engineering Task Force (IETF) and other standards bodies, the protocols required to share multicast source information and to build and program the tree structures into network devices have generally not been sufficiently stable to enable in a multi-party network like the public internet.
The DoubleZero network architecture and supporting protocol make multicast a first class citizen and provide a mechanism to 1.) define multicast group properties on the DZ ledger 2.) allow an owner of a multicast group object to define and manage the allowed publishers and subscribers on the DZ ledger and 3.) deliver host-side and network-side configuration for multicast-enabled tunnels.
For the first time, DoubleZero makes multicast generally accessible to decentralized, high-performance systems like blockchains without requiring the use of a centralized infrastructure.
What is Multicast?
Multicast is a communication method in IP networks where a single packet is sent from a source to multiple destinations simultaneously, but only to those who explicitly express interest in receiving it.
Multicast operates over the IP range 224.0.0.0 to 239.255.255.255 (IPv4). To ensure global uniqueness and no overlap with other multicast services, RFC3180 defines a standard for owners of an autonomous system to use that value to derive a globally unique range. For example, the DoubleZero testnet environment allocates multicast addresses from the range 233.84.178.0 to 233.84.178.255 that corresponds with AS21682.
The following protocols are used within the DoubleZero physical network to enable multicast:
- PIM (Protocol Independent Multicast) for establishing control plane structures between both DoubleZero devices and DoubleZero clients.
- MSDP (Multicast Source Discovery Protocol) for multicast source sharing between DoubleZero devices.
Key characteristics of multicast:
- Receiver-Driven: Only receivers that opt-in by joining a multicast group receive the data.
- Network-Based Replication: Instead of the sender sending multiple copies, routers replicate data only at points of divergence.
- Scalability: Scales well when the number of receivers increases, as sender workload remains constant.
- Application Layer Support: Applications must be designed to use multicast sockets (e.g., setsockopt with IP_ADD_MEMBERSHIP in C/C++).
Multicast vs. Unicast summary

Why It Matters
Dissemination of State
In distributed systems—especially blockchains—nodes must frequently receive the same data (e.g., new transactions, blocks, consensus messages). A unicast approach would require the sender to duplicate and transmit identical data to each recipient individually, which scales linearly with the number of peers.

Multicast changes the model: send once, deliver to many. Ideal for:
- Broadcasting block proposals and consensus votes
- Real-time state replication
- Gossip protocol optimization
- Live data feeds (oracles, price tickers, telemetry)
Bandwidth Utilization and Latency Reduction
By eliminating redundant transmissions, multicast:
- Reduces bandwidth consumption: Crucial when block size or message size is large.
- Minimizes latency: Especially when every millisecond matters during consensus rounds or high-frequency data propagation.
This is particularly beneficial in blockchains where fairness and propagation speed affect consensus security and performance.
Real-World Applications and Implications
- Blockchain networks: Consensus protocols like Tendermint, HotStuff, or Narwhal-Dag could reduce message complexity and speed up rounds using multicast.
- Decentralized live video streaming: Stream once, deliver everywhere without CDNs.
- Real-time sensor grids (IoT): Efficiently update thousands of sensors with control signals.
- Order book and price feed synchronization: In decentralized exchanges or oracle networks.
What's Next?
We are collaborating with development teams throughout the Solana ecosystem to integrate multicast sending/receiving operations into various parts of their software stack. As beta versions become available, we’ll coordinate experiments with the DoubleZero testnet user community to validate performance and stability.
View the multicast connect docs here: https://docs.malbeclabs.com/connect-multicast/
Or to join the DoubleZero testnet as a Solana validator operator, you may apply here: https://doublezero.xyz/connect
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