Default to 2/3 instead of 1/3 for IBC client security parameters

[adizere]

Summary

Replace the 1/3 default with a 2/3 default.

Context: see the recommendation following the work by Tendermint team here: tendermint/tendermint#9420

Acceptance Criteria

• replace default trust threshold from 1/3 to 2/3 for IBC client security params
• test relaying in a multi-network testate setup and confirm no impact is observed when validator sets continuously overlap
  • we should see no changes in the frequency of client updates or in the cost of client update messages
  • note: we already did some interesting tests in production with 1/1 trust threshold, refer to Retrieve minimal set from light client and include supporting headers in client updates #1058

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[crodriguezvega]

@adizere Since the trust threshold is configurable, will there be some kind of validation to check that the threshold is >= 2/3? Otherwise an operator might choose to use a lower threshold anyway...

[adizere]

@adizere Since the trust threshold is configurable, will there be some kind of validation to check that the threshold is >= 2/3? Otherwise an operator might choose to use a lower threshold anyway...

The value is already validated to be > 0 and <1, that is, any value chose by an operator with Hermes must be a valid fraction larger than 0 and smaller than 1. But we don't plan to perform validation that it should always be >= 2/3. I think it's reasonable to allow operators to select different other values, eg 1/3 if they wish so. Do you see concerns with this?

[romac]

We currently only relay on clients with a trust threshold >= 1/3 and <= 2/3. Should we relax the upper bound to 1/1?

[adizere]

Should we relax the upper bound to 1/1?

Not sure why we'd need that in the context of this issues. But I don't see problems with this change either!

[romac]

@ancazamfir What do you think?

[ancazamfir]

@ancazamfir What do you think?

I think we should keep the >=1/3 for now and change default to 2/3. If someone wants <1/3 they can create the client through other means. So maybe at some point we can allow that with a big warning.

[romac]

Agreed. I was asking about the upper bound, should we relax it to 1/1?

[ancazamfir]

Agreed. I was asking about the upper bound, should we relax it to 1/1?

sorry i missed the question completely. I don't see a reason to change the upper bound.

[romac]

Alright :)