Adjusting Target Topology for Caffeine Scaling: 60 application subnets and a US subnet

[wpb]

@Lorimer

rather than something wishy-washy that will be tweaked based on concerns other than security and/or compliance.

@Lorimer

It’s also a slippery slope. I would prefer to see a 10 node subnet if there’s going to be an attempt to shoehorn something in

There is nothing wishy-washy, slippery, or shoehorn about the proposal. It is very consistent with the thoughtful analysis that helped us arrive at our current subnet topology.

@bjoernek

From the previous blog post, we know that decentralization, considered on a standalone basis, is well-achieved for data centers and data center providers and near optimal for node providers. For the country characteristic the current node set shows a lower degree of decentralization.

@bjoernek

Decentralization target:

• The node provider, data center, and data center provider characteristics, which already showcase a higher degree of decentralization, could adhere to stricter targets, demanding maximum decentralization (subnet limit = 1).
• Currently exhibiting the least decentralization, it seems logical to, at least initially, set a comparatively weaker decentralization target for the country characteristic. This would permit the same country to appear up to twice in any given subnet (country subnet limit = 2).

DFINITY conducted a very thorough analysis of the existing decentralization characteristics of the node distribution for the purpose of assessing how strict the decentralization targets should be set. At the time, when all subnets were global in nature, it made sense to set the data center provider (owner) target at a subnet limit of 1. Now that we have a need for regional subnets, the same thoughtful analysis is being applied. In the US we only have 10 unique data center owners. Hence, the subnet limit of 1 doesn’t make sense and is not practical. Given that these data center owners are large corporations that enter into significant and legally binding contracts with node providers that establish clear expectations for privacy and security of the node machines that they host, there is no logical reason not to relax the decentralization target for data center owners to 2. This is no different than the analysis and conclusion that was reached on the decentralization target for the country subnet limit, which is currently set at 2 for smaller subnets and 3 for larger subnets.

We need to be making sensible decisions about subnet topology, which is what this proposal achieves.

[Lorimer]

My point is that if the NNS is prepared to weaken the IC Target Topology here and there (rather than maintain, or strengthen it over time), then it’s anyone’s guess what decentralisation safeguards we’ll have in several years time (with more demand). I don’t think that’s good at all, and it’s why I’d like to see a more rigorously specified topology which we can depend on. Demand, and relative availability of nodes, is not static with respect to any subnet.

@Lorimer

Another problem that exists is rigidity of the IC Target Topology. I believe it would be much more useful to have a target topology expressed as a set of tolerances (optimal configuration on one end of the tolerance, and the worst allowed on the other).

I’d support a proposal that redefines the IC Target Topology as a set of tolerances that apply to all subnets, with special cases only when they make sense for the right reasons (as is currently the case as you mention), i.e.

• Larger subnets can manage slightly more forgiving tolerances on less critical dimensions
• Subnets with specific roles where the role directly relates to a dimension (e.g. country and regulatory compliance)

If some dimensions really are less important in general, the standard tolerances can express that.

This would be a good opportunity to represent Continent, and possibly ISP, as additional dimensions.

It would also be an opportunity to address the out-of-date records.

[Afre]

Fully agree.

Analysis is required for emerging scenarios. Regional subnets require decisions based on the context of that specific region.