Explicit Peering Agreement implementation

[thedevbirb]

Context

Teku implements the concept of a “trusted”/”static” peer, which guarantees the ability to always remain connected to a peer ignoring defensive measures such as peer scoring, however it provides no guarantees of being part of their mesh or to send/receive full messages from them unconditionally.

Why explicit peering agreement

Gossipsub v1.1 introduces the concept of "Explicit Peering Agreement", which is an agreement that must be reached from a pair of nodes in order to “remain connected to and unconditionally forward messages to each other outside of the vagaries of the peer scoring system and other defensive measures”.

This feature if enabled in Teku could allow nodes to explicitly connect to some relays networks such as Fiber or Bloxroute to boost the propagation of their blocks.

Possible implementation

Most of the work for supporting explicit peers (called "direct peers" in Teku and in jvm-libp2p) has been done in #3576. However, direct peers seem to be never assigned (I'd be happy to know I'm wrong). As such, there are only few things that needs to be done:

• set them from the command line
• allow them to be added and removed dynamically
• exclude them from peer scoring or other defensive measures

Lastly this list of nodes needs to be passed to the libp2p implementation.

If there is interest, we can open a PR that implements this functionality.

[tbenr]

Thanks for raising. We are evaluating it.

[mempirate]

Hello @tbenr, any questions we can answer to help with evaluation?

[mempirate]

We have implemented explicit peering agreements in Lighthouse as trusted peers:

• Explicit peers sigp/lighthouse#5333

If you agree with this approach, we'll open a PR that implements this. They can also be defined as an additional flag instead.

[tbenr]

Hey, sorry for the delay. The only concern I have is this:
If direct peers are always part of node meshes, it is not necessarily true that we want to have static peers being direct peers too. Image you have a node with several static peers in several regions of the globe, you may want to have direct peers to be only co-located ones. So if my reasoning is true we may want to specify only a subset of static peers to be direct peers.

WDYT?

[mempirate]

I think that makes sense. In the context of Lighthouse they didn't want to introduce another CLI flag, which is why we went with this approach. If you agree, we can start drafting a PR that adds an --explicit-peers flag and related functionality in the networking stack.

[thedevbirb]

Hey @tbenr, if you want you can check out a draft of what an implementation of this could look like in #8098. Let me know what you think! Thanks a lot.