________________________________
From: Gautam Akiwate <[email protected]>
Sent: Monday, June 2, 2025 6:56 PM

...

> Currently, as defined in the draft the server can publish multiple SVCB RRs 
> (each with a different “sla” value) with the OS filtering down to the correct 
> SVCB RR based on the request service level. With the 0-255 range, we are 
> implicitly asking the OS to go through ~250 SVCB RRs if we expect a server to 
> use the entire range for different OSes etc.

I don't think this is true.  Each RR can have multiple "sla" values.  
Presumably, server deployments would configure a number of RRs that reflects 
the tiered structure of their service, and tag each RR with all the applicable 
"sla" values.

> Instead of expanding the range that drastically, we can get rid of the labels 
> (“background” etc) and just have a numeric range with the lower numbers 
> indicating lower cost and maybe lower performance. We then leave the 
> specifics of how a client can request a specific service level for its 
> network request to the OS. As an example, we can state how traffic classes 
> can be used by the OS to map the request appropriately with the default going 
> to the highest defined value.

>> Also, the draft's use of "realtime" does not match any CDN architecture I've 
>> encountered.

> Yeah. It was us adding a third class to accommodate for future. But the 
> background vs not background would be the primary use case. If anything, this 
> fact seems to be an argument for just two classes for now?

That seems reasonable to me.  Perhaps you would like a SvcParam named 
"background-priority" that overrides SvcPriority for "background" requests, and 
is otherwise ignored?

...

>> Yes, but suppose the "less expensive" option also has lower latency for a 
>> particular user (e.g. a user who happens to be near the data center).  
>> Should that user choose the higher-cost option?  If not, it might be better 
>> to signal the cost hierarchy and let the client use latency to find the 
>> Pareto-optimal server.

> Do you think going to be a numeric range combined with leaving the specifics 
> to the OS of how a client can request a specific service level achieve get to 
> this? If a client/OS wanted to support this they could allow an application 
> to mark their requests accordingly?

I think "background-priority" would make the expectations pretty clear.  The 
OS/client just has to determine if the request is "background", and adjust the 
effective SvcPriority if so.

It wouldn't provide any fancy latency-driven optimal selection behavior, but it 
also would never be worse than the status quo.

--Ben
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