The 3 Types of VPN(Virtual Private Layer)

1.) INTRANET VPN - If a company has one or more remote locations that they wish to join in a single private network, they can create an intranet VPN to connect LAN to LAN.

2.) EXTRANET VPN - When a company has a close relationship with another company (for example, a partner, supplier or customer), they can build an extranet VPN that connects LAN to LAN, and that allows all of the various companies to work in a shared environment.

3.) Remote-Access VPN - also called a virtual private dial-up network (VPDN), is a user-to-LAN connection used by a company that has employees who need to connect to the private network from various remote locations.

Data Center Technology - Technology infrastructures are a costly investment and require constant vigilance to protect and maintain. As networks increase in size, reach, and sophistication, so does their cost.



(WAN) Wide Area Networks












VIRTUAL PRIVATE NETWORKS















STORAGE - Area Networks

METROPOLITAN - Area Networks














BROADCAST DOMAIN















(LAN) Local - Area Networks

OPEN SYSTEM INTERCONNECTION LAYER AND FUNCTIONS

APPLICATION LAYER - is the seventh level of the seven-layer OSI model, and the top layer of the TCP/IP model. It interfaces directly to and performs common application services for the application processes; it also issues requests to the Presentation Layer (OSI).

PRESENTATION LAYER - is responsible for the delivery and formatting of information to the application layer for further processing or display. It relieves the application layer of concern regarding syntactical differences in data representation within the end-user systems.

SESSION LAYER - provides the mechanism for opening, closing and managing a session between end-user application processes, i.e. a semi-permanent dialogue. Communication sessions consist of requests and responses that occur between applications. Session Layers are commonly used in application environments that make use of remote procedure calls (RPCs).

TRASPORT LAYER - is a group of methods and protocols within a layered architecture of network components, within which it is responsible for encapsulating application data blocks into datagrams (packets) suitable for transfer to the network infrastructure for transmission to the destination host, or managing the reverse transaction by abstracting network datagrams and delivering them to an application.

NETWORK LAYER - is responsible for end-to-end (source to destination) packet delivery including any routing through intermediate hosts, whereas the link layer is responsible for node-to-node (hop-to-hop) frame delivery on the same link.

DATA - LINK LAYER - is the layer which transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment. The Data Link Layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the Physical layer.

PHYSICAL LAYER - is a fundamental layer upon which all higher level functions in a network are based. However, due to the plethora of available hardware technologies with widely varying characteristics, this is perhaps the most complex layer in the OSI architecture.

NETWORKING I

COLLISION - is an isolated event in which two or more bodies (colliding bodies) exert relatively strong forces on each other for a relatively short time.


TYPES OF COLLISIONS

1. LOCAL COLLISION - in CSMA/CD computer networks, is a collision that occurs at the NIC as opposed to on the wire. On UTP cable a local collision is detected on the local segment only when a station detects a signal on the RX pair at the same time it is sending on the TX pair.

2. REMOTE COLLISION - in CSMA/CD computer networks, is a collision that occurs when a frame having length less than minimum length and with an incorrect FCS (Frame Check Sequence), is transmitted. This frame causes a collision at the remote end which will not be detected by the transmitter.

3. LATE COLLISION - is a type of collision found in the CSMA/CD protocol standard. If a collision error occurs after the first 512 bit times of data are transmitted by the transmitting station, a late collision is said to have occurred. Importantly, late collisions are not re-sent by the NIC unlike collisions occurring before the first 64 octets; it is left for the upper layers of the protocol stack to determine that there was loss of data.

JABBER - is an initiative to produce an open source, XML-based instant messaging platform. Similar to the Linux and Apache projects, Jabber developers volunteer their time to work with the code over the Internet.

COLLISION DOMAIN - is a physical network segment where data packets can "collide" with one another for being sent on a shared medium, in particular in the Ethernet networking protocol. This is an Ethernet term used to describe a network scenario wherein one particular device sends a packet on a network segment, forcing every other device on that same segment to pay attention to it.

MULTIMODE FIBER (multimode fiber or MM fiber or fibre) - is a type of optical fiber mostly used for communication over shorter distances, such as within a building or on a campus. Typical multimode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters—more than sufficient for the majority of premises applications.

SINGLE-MODE FIBER (SMF) - is an optical fiber designed to carry only a single ray of light (mode). This ray of light often contains a variety of different wavelengths. Although the ray travels parallel to the length of the fiber, it is often called the transverse mode since its electromagnetic vibrations occur perpendicular (transverse) to the length of the fiber. Single-mode optical fibers are also called monomode optical fibers, single-mode optical waveguides, or unimode fibers.


PICTURE FOR LOOSE - TUBE FIBER














PICTURE FOR TIGHT - BUFERRED FIBER