6.8 KiB
| title | name | editor | contributors |
|---|---|---|---|
| WAKU-RENDEZVOUS | Waku Rendezvous discovery | Prem Chaitanya Prathi <premprathi@proton.me> | Simon-Pierre Vivier <simvivier@status.im> |
Abstract
This document describes the goal, strategy, usage, and changes to the libp2p rendezvous protocol by Waku.
Rendezvous is one of the discovery methods that can be used by Waku. It supplements Discovery v5 and Waku peer exchange.
Background and Rationale
Waku needs discovery mechanism(s) that are both rapid and robust against attacks. Fully centralised discovery (such as DNS lookup) may be fast but is not secure. Fully decentralised discovery (such as discv5) may be robust, but too slow for some bootstrapping use cases Rendezvous provides a limited, balanced solution that trades off some robustness for speed. It's meant to complement not replaced fully decentralised discovery mechanisms, like discv5
By combining rendezvous with Discv5 and 34/WAKU2-PEER-EXCHANGE, Waku nodes can more quickly reach a meaningful set of peers than by relying on a single discovery method.
Semantics
Waku rendezvous extends the libp2p rendezvous semantics by using WakuPeerRecord instead of the standard libp2p PeerRecord.
This allows nodes to advertise additional Waku-specific metadata beyond what is available in the standard libp2p peer record.
Specifications
Libp2p Protocol identifier: /vac/waku/rendezvous/1.0.0
Wire Protocol
Nodes advertise their information through WakuPeerRecord, a custom peer record structure designed for Waku rendezvous.
Since this is a customPeerRecord, we define a private multicodec value of 0x300000 as per multicodec table.
The WakuPeerRecord is defined as follows:
WakuPeerRecord fields:
peer_id: The libp2p PeerId of the node.seqNo: The time at which the record was created or last updated (Unix epoch, seconds).multiaddrs: A list of multiaddresses for connectivity.mix_public_key: The Mix protocol public key (only present for nodes supporting Mix).
Encoding: WakuPeerRecord is encoded as a protobuf message. The exact schema is:
message WakuPeerRecord {
string peer_id = 1;
uint64 seqNo = 2;
repeated string multiaddrs = 3;
optional bytes mix_public_key = 4;
}
When a node discovers peers through rendezvous, it receives the complete WakuPeerRecord for each peer, allowing it to make informed decisions about which peers to connect to based on their advertised information.
Namespace Format
The rendezvous namespaces used to register and request peer records
MUST be in the format rs/<cluster-id>/<capability>.
<capability> is a string representing the individual capability for which a discoverable Waku peer record is registered.
The Waku peer record is separately registered against each capability for which discovery is desired.
The only defined capability for now is mix, representing Waku Mix support.
For example, a Waku peer record for a node supporting mix protocol in cluster 1 will be registered against a namespace: rs/1/mix.
This allows for discovering peers with specific capabilities within a given cluster.
Currently, this is used for Mix protocol discovery where the capability field specifies mix.
Refer to RELAY-SHARDING for cluster information.
Registration and Discovery
Every Waku Relay node SHOULD be initialized as a rendezvous point.
Each relay node that participates in discovery MUST register with random rendezvous points at regular intervals. The RECOMMENDED registration interval is 10 seconds.
All relay nodes participating in rendezvous discovery SHOULD advertise their information using WakuPeerRecord. For nodes supporting the Mix protocol, the mix_public_key field MUST be included.
All advertised records MUST conform to the WakuPeerRecord definition.
It is RECOMMENDED that rendezvous points expire registrations after 1 minute (60 seconds TTL) to keep discovered peer records limited to those recently online.
At startup, every Waku node supporting Mix SHOULD discover peers by sending requests to random rendezvous points for the Mix capability namespace.
It is RECOMMENDED a maximum of 12 peers be requested each time. This number is sufficient for good GossipSub connectivity and minimizes the load on rendezvous points.
Operational Recommendations
It is RECOMMENDED that bootstrap nodes participate in rendezvous discovery and that other discovery methods are used in conjunction and continue discovering peers for the lifetime of the local node.
For resource-constrained devices or light clients, a client-only mode MAY be used where nodes only query for peers without acting as rendezvous points themselves and without advertising their own peer records.
Future Work
The protocol currently supports advertising Mix-specific capabilities (Mix public keys) through WakuPeerRecord.
Future enhancements could include:
- Extending
WakuPeerRecordto advertise other Waku protocol capabilities (Relay, Store, Filter, Lightpush, etc.) - Supporting shard-based namespaces (e.g.,
rs/<cluster-id>/<shard>) for general relay peer discovery without capability filtering - Batch registration support allowing nodes to register across multiple namespaces in a single request
Copyright
Copyright and related rights waived via CC0.