Folks,
Eric said:
> 1. It is slower because it requires two handshakes.
> 2. The client may have to authenticate twice (this is a special
> case of (1)).
>
> The second case can be easily ameliorated by having the client send an
> extension (empty UME?) in the first handshake as a signal that it wants
> to do UMDL and that the server should hold off on demanding client
> authentication until the rehandshake happens.
>
> The performance issue is quite modest with modern servers. Indeed, it's
> quite common for web servers to do a first handshake without cert-based
> client auth and then rehandshake with client auth if the client asks for
> a sensitive page.
This raised a flag with me. Within the Internet protocol context I have always
seen significant concern for reducing the number of exchanges, because
additional exchanges (hand-shakes) can -- and often do -- have painful
round-trip latencies. (Server capacity can be a concern, of course, but not for
this issue.)
For all of the massive improvements in the Internet's infrastructure, my
impression is that round-trip delays can still be problematic.
To this end, the high chatter rate of http seems less a basis for encouraging
other protocols to chatter more, than a case of remarkable good luck... unless
you happen to be on a path that has high latencies frequently, or experience too
many of these extra handshakes.
Is it true that we no longer need to worry about regularly adding extra
round-trips to popular protocols that operate over the open Internet?
d/
--
Dave Crocker
Brandenburg InternetWorking
<http://bbiw.net>
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