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132 lines
6.8 KiB
Markdown
132 lines
6.8 KiB
Markdown
---
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title: WAKU-RENDEZVOUS
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name: Waku Rendezvous discovery
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editor: Prem Chaitanya Prathi <premprathi@proton.me>
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contributors: Simon-Pierre Vivier <simvivier@status.im>
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---
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## Abstract
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This document describes the goal,
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strategy, usage, and changes to the libp2p rendezvous protocol by Waku.
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Rendezvous is one of the discovery methods that can be used by Waku.
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It supplements Discovery v5 and Waku peer exchange.
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## Background and Rationale
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Waku needs discovery mechanism(s) that are both rapid and robust against attacks.
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Fully centralised discovery (such as DNS lookup) may be fast but is not secure.
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Fully decentralised discovery (such as discv5) may be robust, but too slow for some bootstrapping use cases
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Rendezvous provides a limited, balanced solution that trades off some robustness for speed.
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It's meant to complement not replaced fully decentralised discovery mechanisms, like discv5
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By combining rendezvous with
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[Discv5](https://github.com/ethereum/devp2p/blob/bc76b9809a30e6dc5c8dcda996273f0f9bcf7108/discv5/discv5.md#node-discovery-protocol-v5) and
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[34/WAKU2-PEER-EXCHANGE](https://github.com/vacp2p/rfc-index/blob/dd397adc594c121ce3e10b7e81b5c2ed4818c0a6/waku/standards/core/34/peer-exchange.md#abstract),
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Waku nodes can more quickly reach a meaningful set of peers
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than by relying on a single discovery method.
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## Semantics
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Waku rendezvous extends the [libp2p rendezvous semantics](https://github.com/libp2p/specs/blob/69c4fdf5da3a07d2f392df6a892c07256c1885c0/rendezvous/README.md#rendezvous-protocol) by using `WakuPeerRecord` instead of the standard libp2p `PeerRecord`.
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This allows nodes to advertise additional Waku-specific metadata beyond what is available in the standard libp2p peer record.
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## Specifications
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**Libp2p Protocol identifier**: `/vac/waku/rendezvous/1.0.0`
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### Wire Protocol
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Nodes advertise their information through `WakuPeerRecord`, a custom peer record structure designed for Waku rendezvous.
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Since this is a customPeerRecord, we define a private multicodec value of `0x300000` as per [multicodec table](https://github.com/multiformats/multicodec/blob/0c6c7d75f1580af329847dbc9900859a445ed980/table.csv).
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The `WakuPeerRecord` is defined as follows:
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**WakuPeerRecord fields:**
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- `peer_id`: The libp2p PeerId of the node.
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- `seqNo`: The time at which the record was created or last updated (Unix epoch, seconds).
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- `multiaddrs`: A list of multiaddresses for connectivity.
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- `mix_public_key`: The Mix protocol public key (only present for nodes supporting Mix).
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**Encoding:**
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WakuPeerRecord is encoded as a protobuf message. The exact schema is:
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```protobuf
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message WakuPeerRecord {
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string peer_id = 1;
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uint64 seqNo = 2;
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repeated string multiaddrs = 3;
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optional bytes mix_public_key = 4;
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}
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```
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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.
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### Namespace Format
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The [rendezvous namespaces](https://github.com/libp2p/specs/blob/69c4fdf5da3a07d2f392df6a892c07256c1885c0/rendezvous/README.md#the-protocol) used to register and request peer records
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MUST be in the format `rs/<cluster-id>/<capability>`.
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`<capability>` is a string representing the individual capability for which a discoverable Waku peer record is registered.
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The Waku peer record is separately registered against each capability for which discovery is desired.
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The only defined capability for now is `mix`, representing [Waku Mix](https://github.com/waku-org/specs/blob/fe5cfdf823085b8c9560df81b38bc342d6b1cb38/standards/core/mix.md) support.
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For example, a Waku peer record for a node supporting mix protocol in cluster `1` will be registered against a namespace: `rs/1/mix`.
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This allows for discovering peers with specific capabilities within a given cluster.
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Currently, this is used for Mix protocol discovery where the capability field specifies `mix`.
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Refer to [RELAY-SHARDING](https://github.com/waku-org/specs/blob/fe5cfdf823085b8c9560df81b38bc342d6b1cb38/standards/core/relay-sharding.md) for cluster information.
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### Registration and Discovery
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Every [Waku Relay](https://github.com/vacp2p/rfc-index/blob/dd397adc594c121ce3e10b7e81b5c2ed4818c0a6/waku/standards/core/11/relay.md) node SHOULD be initialized as a rendezvous point.
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Each relay node that participates in discovery
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MUST register with random rendezvous points at regular intervals.
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The RECOMMENDED registration interval is 10 seconds.
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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.
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All advertised records MUST conform to the `WakuPeerRecord` definition.
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It is RECOMMENDED that rendezvous points expire registrations after 1 minute (60 seconds TTL)
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to keep discovered peer records limited to those recently online.
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At startup, every Waku node supporting Mix SHOULD discover peers by
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sending requests to random rendezvous points for the Mix capability namespace.
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It is RECOMMENDED a maximum of 12 peers be requested each time.
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This number is sufficient for good GossipSub connectivity and
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minimizes the load on rendezvous points.
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### Operational Recommendations
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It is RECOMMENDED that bootstrap nodes participate in rendezvous discovery and
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that other discovery methods are used in conjunction and
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continue discovering peers for the lifetime of the local node.
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For resource-constrained devices or light clients, a client-only mode MAY be used
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where nodes only query for peers without acting as rendezvous points themselves
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and without advertising their own peer records.
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## Future Work
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The protocol currently supports advertising Mix-specific capabilities (Mix public keys) through `WakuPeerRecord`.
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Future enhancements could include:
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- Extending `WakuPeerRecord` to advertise other Waku protocol capabilities (Relay, Store, Filter, Lightpush, etc.)
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- Supporting shard-based namespaces (e.g., `rs/<cluster-id>/<shard>`) for general relay peer discovery without capability filtering
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- Batch registration support allowing nodes to register across multiple namespaces in a single request
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# Copyright
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Copyright and related rights waived via
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[CC0](https://creativecommons.org/publicdomain/zero/1.0/).
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# References
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- [Discv5](https://github.com/ethereum/devp2p/blob/bc76b9809a30e6dc5c8dcda996273f0f9bcf7108/discv5/discv5.md#node-discovery-protocol-v5)
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- [ENR](https://github.com/ethereum/devp2p/blob/bc76b9809a30e6dc5c8dcda996273f0f9bcf7108/enr.md)
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- [34/WAKU2-PEER-EXCHANGE](https://github.com/vacp2p/rfc-index/blob/dd397adc594c121ce3e10b7e81b5c2ed4818c0a6/waku/standards/core/34/peer-exchange.md#abstract)
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- [Libp2p Rendezvous](https://github.com/libp2p/specs/blob/69c4fdf5da3a07d2f392df6a892c07256c1885c0/rendezvous/README.md#rendezvous-protocol)
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- [Relay](https://github.com/vacp2p/rfc-index/blob/dd397adc594c121ce3e10b7e81b5c2ed4818c0a6/waku/standards/core/11/relay.md)
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