Re: [bfcpbis] Eric Rescorla's Discuss on draft-ietf-bfcpbis-rfc4583bis-26: (with DISCUSS and COMMENT)

[Eric Rescorla <[e-mail]>]

On Mon, Dec 3, 2018 at 6:33 AM Christer Holmberg <
[e-mail]> wrote:

> Hi,
>
> ---
>
> >>>>> S 5.5.
> >>>>>      'bfcpver' attribute in offers and answers.  The attribute
> value, if
> >>>>>      present, MUST be in accordance with the definition of the
> Version
> >>>>>      field in [I-D.ietf-bfcpbis-rfc4582bis].  If the attribute is not
> >>>>>      present, endpoints MUST assume a default value in accordance
> with
> >>>>>      [I-D.ietf-bfcpbis-rfc4582bis]: when used over a reliable
> transport
> >>>>>      the default attribute value is "1", and when used over an
> unreliable
> >>>>
> >>>> Just for clarity: UDP over TURN-TCP is an unreliable transport, right?
> >>>
> >>> I would assume so, but I guess that question is not BFCP specific?
> >>>
> >>> Sorry, what I mean is "does BFCP count it as an unreliable transport".
> I agree it is unreliable.
> >>
> >> Do you think we need to add some text about it?
> >>
> >> Related to that, if ICE is used, if both UDP and TCP candidates are
> offered, endpoints might not know what kind of transport will eventually
> >> be selected. Perhaps there should be a note about that?
> >>
> >> Something like:
> >>
> >> "Note: When ICE is used, where the candidates represent both reliable
> and unreliable transports, the ICE process will determine what type of
> transport will eventually be used."
> >
> > Well, ICE can flip-flop the transport, so I think if you have anything
> other than ICE-TCP (which is to say anyone who uses ICE) then you have to
> assume it's unreliable
>
> My point was that when you send the offer, and set the 'bfcpver' attribute
> value, if you use ICE you may not yet know whether the transport will
> eventually be reliable or unreliable (if you offer candidates for both
> reliable and unreliable transports).
>
> I guess we could say that the attribute value must match the transport
> indicated in the 'm' line. That way things will be correct if the remote
> peer does not support ICE.
>

i don't really know what this attribute is used for so it's hard for me to
say.

Can you explain what it does?

-Ekr

Regards,
>
> Christer
>
>
>
>