Re: [Roll] Border router failure detection

[Konrad Iwanicki <[e-mail]>]

Hi Michael,

On 14/10/2022 14:33, Michael Richardson wrote:
> Konrad Iwanicki <[e-mail]> wrote:
>      > On 13/10/2022 18:05, Michael Richardson wrote:
>      >> Konrad Iwanicki <[e-mail]> wrote:
>      >> > 3. Is rebuilding the DODAG in such a case desirable?
>      >> > If the majority of links to the root that have once formed a DODAG
>      >> are
>      >> > currently down, then the DODAG should probably look different than for
>      >> > the network with those links up. Rebuilding the DODAG, at least in my
>      >> > opinion, makes a lot of sense in such a case. Furthermore, the threshold
>      >> > describing how large the majority is is configurable. Depending on whether
>      >> > one wants to prioritize speeding up root failure detection or slowing down
>      >> > DODAG rebuilding, different values can be chosen.
>      >> Do the sentinels need to agree on this threshold?
> 
>      > Yes, they should. This is a configuration parameter of the protocol.
> 
> I don't remember if this goes into the DIO or not.
> Should it?

I does not. I made it a parameter that is configured independent of the 
operation of the protocol. However, if necessary, it can go into the 
option itself.

> what is the effect of the parameter being different on different sentinels?
> (It's a pathological case, but worth thinking about for 30s)

The Sentinels or Acceptors (because the parameter is relevant for them 
as well) that have the lowest setting of the parameter will detect the 
crash the fastest and enforce their decision upon others.

> For me, I clearly should read the document again top to bottom, since it's
> been many months.  I guess I could volunteer to document shepherd.
> I think we should WGLC the document already.
> Perhaps in mid-November, I'll have time to finish debugging my RFC8994
> implementation.  I think that this protocol would be useful in the ACP case,
> but I'd be many months away from implementing.

Good luck then.

Best,
-- 
- Konrad Iwanicki.