Quality of User Experience (was RE: image stream routers)

Valdis.Kletnieks at vt.edu Valdis.Kletnieks at vt.edu
Sat Sep 17 08:10:04 UTC 2005


On Fri, 16 Sep 2005 23:55:05 PDT, "Christopher J. Wolff" said:
> So, if all other elements (software, customer support, and management) are
> equal, what router hardware architecture will contribute to a positive or
> negative user experience?  In other words, if the routing device between my
> workstation and server is a Juniper M7 instead of Pentium IV running
> unix-flavor-of-the-day, how will that affect the quality of user experience?

It depends.  Which part of "gestalt" do you not understand? :)

Right now, the very first hop off my laptop is a dialup that connected at 44K.
The router architecture is the least of my concerns :)   Better/shorter copper
that let it connect at 56K, or getting DSL/cable connectivity would make more
difference.. (Of course, once I get to my office and connect at 100mbit, it
might start mattering ;)

In general, whatever router is in use, be it Juniper or Pentium or Gerbil, will
either keep up with the offered packets/sec, or it won't.  If it doesn't keep
up, packets get dropped and retransmit timers pop, irritating the user. If it
*does* keep up, then your end-to-end latency is basically switching delays and
speed-of-light delays - so the user cares more about the *number* and
*distance* than the actual architecture.  8 hops that include a trip through a
Juniper in Iceland is worse than 2 hops through PC-class hardware to the next
town over (unless the next town over is, in fact, Reykjavik ;)

And remember - the business goal isn't to maximize the user experience, it's
to to find the cheapest configuration that still lets you avoid having to
pay penalties for not meeting the SLA.

Of course, if your user base is $9.95/mo Joe Sixpacks, you really don't have
the revenue stream to support a user experience any better than "sorta works
most of the time"....
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