OSI???????

OSI

(Open Systems Interconnection)

---ito daw ang nagbibigay guide sa product ng implementors kaya ang products will consistently nagtatarbaho sa ibang produkto. The reference model defines seven layers of functions that take place at each end of a communication.

Layer 7: The application layer

--The application layer is the seventh level of the seven-layer OSI model. It interfaces directly to and performs common application services for the application processes; it also issues requests to the presentation layer.(This layer is not the application itself, although some applications may perform application layer functions.) ito daw ay nag papahayag ng

Layer 6: The presentation layer

---This is a layer, usually part of an operating system, that converts incoming and outgoing data from one presentation format to another (for example, from a text stream into a popup window with the newly arrived text). Sometimes called the syntax layer.

Layer 5: The session layer

---This layer sets up, coordinates, and terminates conversations, exchanges, and dialogs between the applications at each end. It deals with session and connection coordination.

Layer 4: The transport layer

---This layer manages the end-to-end control (for example, determining whether all packets have arrived) and error-checking. It ensures complete data transfer.

Layer 3: The network layer

---This layer handles the routing of the data (sending it in the right direction to the right destination on outgoing transmissions and receiving incoming transmissions at the packet level). The network layer does routing and forwarding.

Layer 2: The data-link laye

---This layer provides synchronization for the physical level and does bit-stuffing for strings of 1's in excess of 5. It furnishes transmission protocol knowledge and management.

Layer 1: The physical layer

---This layer conveys the bit stream through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier.

NETWORK TOPOLOGY

Network topology

is the study of the arrangement or mapping of the elements especially the physical (real) and logical (virtual) interconnections between nodes.

1.Ring Topology

- A ring topology is a network topoloLayer or circuit arrangement in which each network device is attached along the same signal path to two other devices, forming a path in the shape of a ring.

2.Mesh Topology-

-A mesh network is a local area network (LAN) that employs one of two connection arrangements, full mesh topology or partial mesh topology. In the full mesh topology, each node (workstation or other device) is connected directly to each of the others. In the partial mesh topology, some nodes are connected to all the others, but some of the nodes are connected only to those other nodes with which they exchange the most data

3. Star topology

The star topology looks like a great way to interconnect a collection of remote devices, but a big problem exists.-a star topology connects N devices in a completely symmetrical, peer-to-peer fashion. Each device in the star connects to a central node where all the wires directly join together

4. Tree topology

- This iscombination of the bus and the Star Topology. The tree like structure allows you to have many servers on the network and you can branch out the network in many ways.

5.BUS TOPOLOGY

-The bus topology connects each computer on the network into something called the segment trunk. A bus is usually referred to a cable that connects end to end and this is used to transmit the signals from one end to the other end.