Heaps of Omnigraffle Stencils

I used Omnigraffle about a year ago then I remember I had difficulties to draw network diagram based on Cisco Stencil. I posted Cisco Stencils for Omnigraffle and that was pretty much the only available Cisco Stencil during that time.

I’m reopening my Omnigraffle ’cause I’m quite lazy to switch to other laptop and start googling for Omnigraffle stencils. I’m quite surprised to know that there is actually a site dedicated just only to provide free Omnigraffle stencils and it includes Cisco stencils. Graffletopia gives you heaps of Omnigraffle stencils for free. The quality is very good and although not all of Cisco stencil are available, it is actually enough to start the work.

Big thanks to Patrick Crowley for the initiative!

How Citrix Works

Taken from Getting Started With Citrix Presentation Server 4.5.

You publish any given application or content once on the server, but multiple users can simultaneously access the published resources. Application processing on the client is kept to a minimum because the application runs entirely on the server. The ICA protocol sends keystrokes, mouse clicks, and screen updates between the server and the client, so to the user of the client device it appears that the software is running locally.

Because applications run on the server and not on the client device, users can connect from any platform. For example, Microsoft Outlook running as a published application looks and feels the same whether the user is connecting from a Windows CE hand-held computer, a Macintosh desktop, or a Linux workstation. You can control user connections to the server to prevent over-consumption of licenses or server resources.

The amorality of Web 2.0 (by Nicholas Carr)

From the start, the World Wide Web has been a vessel of quasi-religious longing. And why not? For those seeking to transcend the physical world, the Web presents a readymade Promised Land. On the Internet, we’re all bodiless, symbols speaking to symbols in symbols. The early texts of Web metaphysics, many written by thinkers associated with or influenced by the post-60s New Age movement, are rich with a sense of impending spiritual release; they describe the passage into the cyber world as a process of personal and communal unshackling, a journey that frees us from traditional constraints on our intelligence, our communities, our meager physical selves. We become free-floating netizens in a more enlightened, almost angelic, realm.

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FDM, TDM, and STDM

Mul-ti-plex [m´ulte pl`eks] n (plural mul-ti-plex-es)
electronic engineering multiple transmission: the simultaneous transmission
of two or more signals along one communications channel

(Microsoft Encarta Reference Library, 2004) [3].

‘Multiplexers (MUXs) act as both concentrators and contention devices to allow multiple, relatively low-speed terminal devices to share a single, highcapacity circuit (physical path) between two points in a network. ‘ (Horak 1996) [2]. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end. (Whatis.com 2004) [4].

MUX exists in both end-point. At one point, it combines several circuits, usually a set of four or multiples of four into one high-capacity circuit and the other end-point is to split them back into several circuits. By putting the wire all together in a single high-capacity line, multiple communications can now be achieved. Multiplexing can be implemented in current transmission media such as twisted pair, coaxial, fiber optic cables, microwave, satellite and radio systems.

The main advantage to use multiplexing is for economic reason. (Horak 1996) [2]. Imagine that without using multiplexer shown in Figure 1, each computer will need its own dedicated physical connection which can cost more rather than combining several circuit into one.

Multiplexing works in a such way that the hosts will not experience what is happening in between. It is MUX job to craft the electric signal and put it into one high-capacity circuit. On another end, other MUX will examine the signal and forward it to a designated host.

As the technology of transmission medium is constanly advancing time to achieve faster delivery and bigger amount of data that can be carried, Multiplexing evolves as well to take advantages of newer technology.

Figure 1: Multiplexed Circuit
Figure 1: Multiplexed Circuit

Nowadays, there are several methods to carry data in a multiplexed environment. This article will describe the varieties of multiplexing technology based on a chronological order. These methods are Frequency Division Multiplexing, Time Division Multiplexing, and Statistical Division Multiplexing.

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