MEX - windowing system - was created in 1985.
The windowing is a feature of manage bandwidth of transferring data.
A period of time when you can do something can be a definition of a window.
Do you mean Tisco (UK) or CISCO
I think you may mean CUCM, which is the "Cisco Unified Communications Manager, "the "brains" of a Cisco Unified Communications system. The product used to be called "Cisco Unified Call Manager" and before that just "Call Manager."
Buffering and windowing
Cisco Technical Documentation
You have passed the cisco minimum requirement to complete a course. So you can get both the certificate of completion, and a letter from cisco. A letter is an addition to the certificate, as it tells that you have done a good job in the course.
flow control
To remove the noise
You mean Ethernet switch? There are many of them: 3COM, ASUS, CISCO, D-Link, Edimax, Linksys (now part of CISCO) and many others.
Some recommended books about Cisco routers are: Cisco Router Configuration, Cisco Routers For The Desperate, Cisco Routers for IP Router, Cisco CCNA Routing and Switching.