CushionTheBlow (구 BluemoonSoft)

An application-specific integrated circuit (ASIC) is an integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC.

In contrast, the 7400 series and 4000 series integrated circuits are logic building blocks that can be wired together for use in many different applications. Intermediate between ASICs and standard products are application specific standard products (ASSPs).

As feature sizes have shrunk and design tools improved over the years, the maximum complexity (and hence functionality) possible in an ASIC has grown from 5,000 gates to over 100 million. Modern ASICs often include entire 32-bit processors, memory blocks including ROM, RAM, EEPROM, Flash and other large building blocks. Such an ASIC is often termed a SoC (System-on-a-chip). Designers of digital ASICs use a hardware description language (HDL), such as Verilog or VHDL, to describe the functionality of ASICs.

Field-programmable gate arrays (FPGA) are the modern day equivalent of 7400 series logic and a breadboard, containing programmable logic blocks and programmable interconnects that allow the same FPGA to be used in many different applications. For smaller designs and/or lower production volumes, FPGAs may be more cost effective than an ASIC design. The Non-recurring engineering cost (the cost to set up the factory to produce a particular ASIC) can run into the millions of dollars.

The general term application specific integrated circuit includes FPGAs, but most designers use ASIC only for non field programmable devices (e.g. standard cell or sea of gates) and make a distinction between ASIC and FPGAs.

Reference;
http://en.wikipedia.org/wiki/Asic

Category 3 cable, commonly known as Cat 3, is an unshielded twisted pair (UTP) cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz. It is part of a family of copper cabling standards defined jointly by the Electronic Industries Alliance and the Telecommunications Industry Association. Category 3 was a popular cabling format among computer network administrators in the early 1990s, but fell out of popularity in favor of the very similar, but higher performing, Cat 5 standard. Presently, most new structured cable installations are built with Cat 5e or Cat 6 cable. Cat 3 is currently still in use in two-line telephone systems, and can easily be adapted to run VoIP (as long as you create a dedicated LAN for your VoIP telephone sets). While Cat 5 or higher is often recommended for VoIP, the reality is that the 10 Mbit/s bandwidth a cat 3 network can provide is far more than the 0.08 Mbit/s a VoIP phone needs at full load, and Cat 3 is even compatible with 802.3af PoE.

Note that unlike Cat 1, 2, 4, and 5 cables, Cat 3 is still recognized by TIA/EIA-568-B, its defining standard.

The newer 100BASE-T4 standard, which achieves speeds of 100 Mbit/s by using all 4 pairs of wires, allowed older Cat 3 based infrastructures to achieve a much higher bandwidth.

Reference:
http://en.wikipedia.org/wiki/Category_3_cable

The 8 Position 8 Contact (8P8C) modular plugs and jacks are communications connectors. Under the same naming scheme, an 8P6C connector has eight positions, with six positions containing conductors, and a 6P6C connector has six positions, all containing conductors. 8P8C connectors are typically used to terminate twisted pair cable.

These connectors are often referred to as RJ45 plugs and jacks. This is technically incorrect because the RJ45 standard specifies both the mechanical interface and a different wiring scheme than T568A/B, which is often used for Ethernet and telephones.

8P8C consists of two paired components: the male plug and the female jack or socket. Each has eight equally-spaced conductors. On the plug, these conductors are flat contacts positioned parallel with the connector body. Inside the jack or socket, the conductors are suspended diagonally toward the insertion interface. When an 8P8C plug is mated with an 8P8C jack, the conductors meet and create an electrical connection. Spring tension in the jack's conductors ensure a good interface with the plug and allow for slight travel during insertion and removal. The 8P8C connector is probably best known for its use in Ethernet. Since about 2000, it is nearly universal as the type of connector used on a cable that carries a single Ethernet network, and has replaced many older connector types. Older connectors have also been phased out as modern cables no longer have the high current and voltage requirements for which the bulkier connectors were designed.

Reference:
http://en.wikipedia.org/wiki/8P8C

IEEE 802.1w is a Rapid Spanning Tree Protocol (RSTP) that can be seen as an evolution of the 802.1 standard. In most cases, RSTP performs better than Cisco Systems' proprietary extensions without any additional configuration. 802.1w is also capable of reverting back to IEEE 802.1D in order to interoperate with legacy bridges (thus dropping the benefits it introduces) on a per-port basis.

The motivations behind the development of this supplement include:

The desirability of developing an improved mode of Bridge operation that, while retaining the plug-and-play benefits of Spanning Tree, discard some of the less desirable aspects of the existing Spanning Tree protocol, in particular the significant time taken for it to re-configure and restore service on link failure/restoration;

The realisation that, while small improvements in Spanning Tree performance are possible through manipulation of the existing default parameter values, it is necessary to introduce significant changes to the way the Spanning Tree algorithm operates in order to achieve major improvements; The realisation that is possible to develop improvements to the operation of Spanning Tree that take advantage of the increasing prevalence of structured wiring approaches, while still retaining compatibility with equipment based on the original Spanning Tree algorithm.

Reference:
http://en.wikipedia.org/wiki/802.1w

IEEE 802.1p is a standard that provides traffic class expediting and dynamic multicast filtering. Essentially, it provides a mechanism for implementing Quality of Service (QoS) at the MAC (Media Access Control) level.

Eight different classes of service are available, expressed through the 3-bit user_priority field in an IEEE 802.1Q header added to the frame. The way traffic is treated when assigned to any particular class is undefined and left to the implementation. The IEEE however has made some broad recommendations.

802.1p is used within the IEEE 802.1D and IEEE 802.1Q standards.

Reference:
http://en.wikipedia.org/wiki/IEEE_802.1p

IEEE 802.1Q (also known as VLAN Tagging) was a project in the IEEE 802 standards process to develop a mechanism to allow multiple bridged networks to transparently share the same physical network link without leakage of information between networks (i.e. trunking). IEEE 802.1Q is also the name of the standard issued by this process, and in common usage the name of the encapsulation protocol used to implement this mechanism over Ethernet networks.

IEEE 802.1Q also defines the meaning of a virtual LAN or VLAN with respect to the specific conceptual model underpinning bridging at the MAC layer and to the IEEE 802.1D spanning tree protocol. This protocol allows for individual VLANs to communicate with one another with the use of a layer-3 router. See also Cisco's proprietary DTP, VTP and ISL for information on inter-switch and inter-VLAN communication.

As an illustration of the utility of VLANs, consider a company whose IT department wishes to provide separate logical networks for each department in the company while using only one physical corporate network. The IT department assigns a unique VLAN per department. Edge switches on the corporate network are configured to insert an appropriate VLAN tag into all data frames arriving from equipment in a given department. After the frames are switched through the corporate network, the VLAN tag is stripped before the frame is sent back to the department's equipment, possibly at a different geographical location. In this way, traffic from one department cannot be leaked to or snooped from another department.

Reference:
http://en.wikipedia.org/wiki/IEEE_802.1Q

IEEE 802.11c is an amendment to the IEEE 802.1D MAC bridging standard to incorporate bridging in wireless bridges or access points. This work is now part of IEEE 802.1D-2004.

802.11c was ratified in October of 1998 and is a supplement to IEEE 802.1D that adds requirements associated with bridging 802.11 wireless client devices. In particular it adds a sub clause under 2.5 Support of the Internal Sublayer Service, to cover bridge operations with 802.11 MACs.

Reference:
http://en.wikipedia.org/wiki/IEEE_802.11c

The Spanning Tree Protocol is an OSI layer-2 protocol which ensures a loop free topology for any bridged LAN. It is based on an algorithm invented by Radia Perlman while working for Digital Equipment Corporation. Spanning tree allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links. Bridge loops must be avoided because they result in flooding the network.

The Spanning Tree Protocol (STP), is defined in the IEEE Standard 802.1D. As the name suggests, it creates a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches), and disables the links which are not part of that tree, leaving a single active path between any two network nodes.

Reference:
http://en.wikipedia.org/wiki/Spanning_tree_protocol