🚀 go-pugleaf

Spark wrote:
> 
> Is there any advantage or disavantage to using the proxy server settings? I
> am not using them now but I am curious.  Below is the AT&T RR quote on the
> subject:
> 
> Thanks,
> spark
> 
> "Our proxy servers enhance the performance of your high-speed connection.
> The proxy server caches - or stores - the most frequently visited sites and
> delivers them upon request. By caching such sites, your request doesn't go
> through the sometimes congested Internet, so you experience a faster
> download. The proxy servers automatically know when content changes, so you
> are always get the most up-to-date pages. This cache is built as AT&T
> Broadband subscribers visit popular sites on the web.
> Although you are not required to use the proxy servers, enabling them will
> result in the best experience. "


Whether using a cache server will improve your performance vs. NOT using
it is dependent on a *lot* of variables.  Realize that there is still a
*cost* of using a cache server:

* If it is handling a lot of users, the cache server can return pages
slower than the target server itself. 

* Cache server is likely caching a lot of the content on *disk*...the
actual web server is likely caching most of the popular pages in
RAM...and thus can deliver pages faster

* Using a cache server still requires *some* communication to the actual
web server.  After you request a page from the cache server, it issues
an HTTP GET to the real server but includes the "if-modified-since
mm/dd/yyy" directive.  It still has to wait for a response, and then may
even have to get the page if it has changed since being cached.

I have actually taken some time to capture some packet traces using and
NOT using a cache server when accessing some popular sites (e.g.
yahoo.com, cnn.com, etc...).

These generalization certainly do NOT apply to all situations, but this
is what I noticed:

* When using a cache server it always took longer for me to START
receving my pages (sometimes 300-1000ms longer).  (presumably this is
the delay to check for page modifications and retrieve the cached data
from disk).  However, once the data started flowing, I would get the
rest of the page at a much faster RATE than talking to the remote
server.

This makes since, because in my case, the cache server was just 1 router
hop away with nearly 45Mbps relatively uncongested bandwidth between me
and it.


Though getting pages directly from the server was actually FASTER is
many cases...it would start sending data almost immediately, though at a
slighly slower pace.  Sometimes the overhead of the cache server is
actually MORE than the delay and congestion incurred to talk to the
remote server---sometimes its less.

Here are cases where cache servers will likely improve your experience:

* You frequently access popular content
* Cache server "close" to you and high-powered
* Providers backbone connections are congested
* Real servers are slow

Here are cases where cache servers will likely degrade your experience:

* Accessing obscure or highly dynamic content
* Cache server is "far" away and/or underpowered
* Providers backbone is NOT congested
* Real servers are very fast (e.g. large web farm with local
load-balancing/caching)

lb.



-- 
-------------------------
Lawrence Baldwin
Protocol Scientist
678-624-0924
http://www.mynetwatchman.com/about.htm - I'm under attack, now what?