question about WAAS

[ronshuster]

We are looking to introduce Cisco WAAS to our WAN environment but I have heard from a colleague that he had experienced performance degradation (over time) through similar technologies…here's why:

Given that encrypted files (.pgp extensions, etc) will not optimize through the cache (though they will improve via TFO), the more files we send that are encrypted (and they will be sent, over time), the more the cache could bloat with 'unique' data packets (data which, by its very nature will not likely be repeated).

So the question is, how is data purged from the cache over time through infrequent use, so that we don't hit a wall after a few months, and are left only with the benefits of TFO and application protocol optimization. (ie... every data transfer acting as though it was a first time transfer - improved, but not optimized).

[Joseph W. Doherty]

I haven't worked with Cisco WAAS, but on other products this issue might be addressed both by cache management replacement policy and/or traffic processing configuration. E.g., for the former, some kind of least-frequently-used policy often purges the "dead wood", for the latter, informing the device not to even cache certain traffic types works even better.