"WAN optimization is a complex and expensive, yet sometimes
required investment. Even if you aren't running a branch office in
Africa over ISDN, the need for WAN optimization and acceleration
exists within nearly every business. The problem is that these
products are extremely expensive. Wouldn't it be great if the same
functionality could be accomplished with commodity PC hardware and
free open source tools?
"Mostly, it can be done.
"What Can't Be Done
"Riverbed and other vendors implement Wide Area File Services
(WAFS), which is a fancy way to say it caches CIFS and NFS data. If
multiple people are working on the same file, or if the same file
gets opened and closed more than once, that data does not really
need to be shipped to the remote file server. It's even fancier
than that; long-term caching of files also makes opening Word
documents, which require a lot of bi-directional communication just
to open, much faster. WAFS implements a (generally) safe mechanism
for caching data when sending it over the WAN would be redundant.
General caching proxies are not optimized for file sharing data,
and will often have to send the whole thing, whereas the WAFS-style
devices can be much more clever about it."