Re: [DNSOP] Spencer Dawkins' Discuss on draft-ietf-dnsop-session-signal-12: (with DISCUSS and COMMENT)

[Spencer Dawkins at IETF <[e-mail]>]

Hi, Benjamin,

On Fri, Jul 27, 2018 at 12:33 PM Benjamin Kaduk <[e-mail]> wrote:

> On Thu, Jul 26, 2018 at 09:33:20PM -0700, Spencer Dawkins wrote:
> > ----------------------------------------------------------------------
> > COMMENT:
> > ----------------------------------------------------------------------
> [snip]
> >
> > This next one is well within the "Spencer wouldn't have done it this
> way, but
> > Spencer's not the working group, or the IETF" range, but
> >
> >   However, in the typical case a server will not know in advance
> >    whether a client supports DSO, so in general, unless it is known in
> >    advance by other means that a client does support DSO, a server MUST
> >    NOT initiate DSO request messages or DSO unacknowledged messages
> >    until a DSO Session has been mutually established by at least one
> >    successful DSO request/response exchange initiated by the client, as
> >    described below.  Similarly, unless it is known in advance by other
> >    means that a server does support DSO, a client MUST NOT initiate DSO
> >    unacknowledged messages until after a DSO Session has been mutually
> >    established.
> >
> > seems fragile, especially in environments where clients can come and go,
> and
> > servers may be addressed using anycast (so I knew in advance that the
> four
> > servers at that anycast address supported DSO, but somebody installed a
> fifth
> > server that does not). Is that unlikely to be a problem?
>
> Note that the client is only prohibted from using "unacknowledged"
> (one-shot) messages -- it can send always normal requests and use the
> presence of a reply to determine server support, on this connection.
> So this seems like a pretty vanilla "client initiates" thing, if I
> understand correctly.
>

Ah - that helps me understand. Thank you for that.

Spencer


> -Benjamin
>
> [snip]
>