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Re: Is round-trip time no longer a concern?

2006-02-20 04:32:25
Dave Cridland wrote:
On Sun Feb 19 23:23:59 2006, Dave Crocker wrote:

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.

as long as you are living in the same rack with them. If you are connected
via UMTS it is a different thing.

> 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 sensitive page.

Indeed there are some webservers around that take so long until my
browser times out.


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.)


Well, for those of us looking at Lemonade, etc, I think we're still very concerned about every round-trip. Server capacity, too, is a very real problem, and, while I admit to not having looked at this specification yet, given what I've read thus far, I'm assuming this has some applicability to email protocols as well as HTTP, which would affect Lemonade.


For all of the massive improvements in the Internet's infrastructure, my impression is that round-trip delays can still be problematic.


Yes, I believe it has something to do with the difficulty of changing the speed of light. Probably requires standards action on a bunch of normative references, or there's a global upgrade problem.


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?


A typical traceroute for me and many, many, many customers of major
german ISPs

 1  echnaton.peter-dambier.de (192.168.48.228)  4.594 ms   5.464 ms   6.267 ms
 2  DARX41-erx (217.0.116.49)  96.478 ms   101.004 ms   111.541 ms
 3  sepia (217.0.67.102)  115.774 ms   123.485 ms   131.139 ms
 4  62.154.15.2  147.919 ms   155.120 ms   162.845 ms
 5  gb-10-0-0.saams.nl.easynet.net (195.69.144.137)  171.365 ms   178.635 ms   
187.107 ms
 6  213.201.252.10  267.804 ms   270.174 ms   272.507 ms
 7  Scylla (213.201.229.65)  269.246 ms   272.058 ms   274.653 ms
 8  Charybdis (84.22.96.250)  98.668 ms   107.666 ms   111.906 ms
 9  Bifroest (84.22.96.246)  124.170 ms   128.057 ms   138.825 ms
10  tourelle (84.22.100.150)  148.487 ms   158.490 ms   163.288 ms

Except for (192.168.48.228) 4.594 ms (my old 486-SLC/2 router, 66 MHz) all are
fast modern machines. That DARX41-erx (217.0.116.49) 96.478 ms is a top model.

So 300 msec forward + 300 msec backward will become 1.2 seconds.
Vaja con dios VoIP.


No.

As far as I'm aware, there is no protocol in existence which somebody, somewhere, does not actively use over a mobile phone link, or a slow analogue modem, and this is especially true of TLS enabled protocols such as HTTP, email protocols, etc.

Dave.


Peter

--
Peter and Karin Dambier
The Public-Root Consortium
Graeffstrasse 14
D-64646 Heppenheim
+49(6252)671-788 (Telekom)
+49(179)108-3978 (O2 Genion)
+49(6252)750-308 (VoIP: sipgate.de)
mail: peter(_at_)peter-dambier(_dot_)de
mail: peter(_at_)echnaton(_dot_)serveftp(_dot_)com
http://iason.site.voila.fr/
https://sourceforge.net/projects/iason/


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