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

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@peter-dambier.de
mail: peter@echnaton.serveftp.com
http://iason.site.voila.fr/
https://sourceforge.net/projects/iason/

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