[RSSAC Caucus] Metrics vantage point connectivity

[Wessels, Duane]

> On Dec 19, 2019, at 1:04 PM, Paul Hoffman <paul.hoffman at icann.org> wrote:
> 
> Greetings again. The current text on vantage point connectivity says:
> 
>> 3.3    Connectivity and Other Requirements
>> 
>> Vantage points shall be hosted inside data centers with reliable power and diverse connectivity providers.
>> 
>> Vantage points within the same geographic region should use different connectivity providers if at all possible. E.g., VP#1 uses ISP#1, VP#2 uses ISP#2, etc. Diversity of connectivity providers helps to increase RSS coverage and avoid situations where multiple vantage points all reach the same root server instance.
>> 
>> Vantage points may be deployed on “bare metal” or virtual machines (VMs). When VMs are utilized, they should provide dedicated IP addresses and a dedicated operating system environment.

Hi Paul, thanks for the comments.

> 
> In essence, the text in the second paragraph requires that every vantage point allow provisioning of the connectivity provider.

I don't see it as a strict requirement.  It says "should" and "if at all possible."  If the "if at all possible" part makes the statement too strong then its okay with me to remove it.

> It basically restricts the kind of VMs that could be used, since none of the widely-used VM providers I have found allow for such provisioning. In fact, it kinda pushes the vantage points to be on bare metal, since those rentals are more likely to allow such provisioning. 

If bare metal gives us better connectivity diversity then I think thats the right way to go.

> Given that the regions are quite large and so the cities could be quite far from each other, it is not clear how much advantage (if any) this restriction would have. It is also not clear why the diversity is given just for within a region.

Diversity within a region seems like a reasonable compromise to me, rather than specifying global diversity, which would be harder.

> 
> Separately, the text "E.g., VP#1 uses ISP#1, VP#2 uses ISP#2, etc." is not terribly grammatical. It also uses "ISP" instead of "connectivity provider". It doesn't add anything to the paragraph, and can safely be removed.

Agreed its not good grammar.  I'm okay with removing it or improving its grammar.

> 
> If this is really what RSSAC wants, that's fine, but it will place limits on which cities can have vantage points because not all cities have data centers that allow this kind of provisioning. If RSSAC instead wants to give itself more freedom for vantage point placement, maybe just change the second paragraph to:
> 
> Having diverse connectivity providers for the vantage points helps to increase RSS coverage and avoid situations where multiple vantage points all reach the same root server instance. The network routing used by vantage points is detectable using the measurements described in Section 4.8. If configuring particular vantage points allows selecting a connectivity provider, this can be used to increase the diversity of the measurement system.

IMO, at this point, RSSAC should say how it would like the system to work.  i.e., that connectivity diversity is a design goal.  I like the first part of your paragraph but I don't like that the latter part prioritizes VM selection over connectivity diversity.

DW


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