Re: [Ice] Proposal for ICE "network cost"

[Peter Thatcher <[e-mail]>]

On Thu, Apr 7, 2016 at 10:50 AM, Emil Ivov <[e-mail]> wrote:

> On 21.03.16 г. 19:07, Peter Thatcher wrote:
>
>> As an author (not a chair), I just submitted a draft for an idea I'd
>> like to propose for ICE: network cost.
>>
>> Here's the draft:
>>
>> https://datatracker.ietf.org/doc/draft-thatcher-ice-network-cost/
>>
>>
>> The idea is basically to allow the controlled side to tell the
>> controlling side which candidates "cost" more than others (such as
>> cellular costing more than Wi-Fi).  This is different than candidate
>> priority for reasons explained in the draft.
>>
>
> I see the value here but I have a few problems with the current state.
>
> To begin with, I find the "cost" name overly confusing. I realize the
> draft already says this is not necessarily real cost but it still leaves
> people with the wrong impression (and I've confirmed this in conversations
> these days). So let's just go for bias or something (I also like fondness).
>

​There are two question here:  the name and the direction.  The choice of
direction is more important than the name.  I prefer the direction where 0
means "free/use-freely" and a big number means
"expensive/restrained/last-resort".  This is because if we ever expand the
range, I think it would be better in the direction of "I really don't want
to use this" rather than "this is even more free to use".  You'll note that
this direction is the opposite of fondness/preference/priority.

In other words, I think modeling this as "badness' is better than as
"goodness".

So if we're going to debate names, let's debate synonyms of "badness".  The
best I could come up with is cost.  But I'd love to hear good synonyms.​
​


>
> The draft is not currently very explicit about exactly how this works in
> the selection of candidates but I assume it basically means: "if it's all
> the same to you, I'd much rather you get in touch with me here than there."
>
>
Close.  0 means "use this freely".  A small number means "I'd rather not
use this".  A large number means "Only use this if nothing else works".​
​



> The trickiest part here is how to assign importance to this new bias as
> opposed to existing metrics such as RTT for example. We could say it's up
> to implementations or try to come up with some recommendation for a formula.
>

​That's exactly what I think we should do: standardized how information is
conveyed from controlled to controlling, but then let the controlling side
decided how to select and nominate.​
​



> The other thing is that I cannot at all see the value of the network ID.
> Why is this necessary?


​Technically, I could make it a separate draft, but the kind of go well
together (they both fit in one nice STUN attribute, for example).

The value of network ID is the following:  if the remote side's network
interface changes, it's wise to notify your bandwidth estimator, because
the change may have been drastic (wifi to 2g).  ​ It could change either by
TURN mobility, or by continual gathering, or by the use of backup candidate
pairs (I realized the last two are not yet standardized).



>
>
> Emil
>
> --
> https://jitsi.org
>