What's the difference between Cisco WAAS en WAE

Question

To facilitate WAN optimization Cisco has several options available.

One option is to deploy 2 (or more) WAAS capable routers e.g. 1941 with WAAS software (and the maximum RAM) talking to each other.

But then there is also a WAE option. This is a storage box with a harddisk, cpu and RAM.
I'm not sure what the WAE provides on top of just the router with WAAS software.

My question is: what is the difference between the two.
Do I need both options if I want WAAS to work in my WAN, or is the WAE an optional extension?

If so what extra does it provide?

I've had a look at the Cisco documentation available, but it just confuses me. They don't clearly differentiate the difference between the options and whether something is optional or required.

Answer 1

Yes, generally you need at least one WAE device for the head-end or Core. For a very simple point to point scenario it is possible to use two routers running Express, but the optimization will be relatively low since DRE won't be used.

As far as I recall the software version in the 1941 is only WAAS Express, which does not save the data to disk. This has major limitations because a feature like DRE which is deduplication needs quite large disk space to work most efficiently. Due to memory limitations, DRE is disabled on the 1921, which further limits the efficiency of the optimization.

The WAE/WAVE appliances are the real deal that provide the full feature set. A while ago Cisco had a few small WAE modules for the first generation ISR's like the 2800. These modules had a CPU and laptop hard drive which provided the required resources for the advanced features.

If you want a minimal and simple Wan Optimization solution, then the WAAS Express could be an option. If the requirement is to reduce network traffic volumes, look for something that stores the deduplication data on disk.