Conceptos basicos de redes

BASIC’SNETWORK CONCEPTS

Las Americas Institute of Technology

Network Infrastructure Essentials: Basic’s Network Concepts Presented by: Frank David De La Cruz

Learn about network topologies

Learn about the OSI model

Understand physical layer functions

Understand data link layer functions

Learn about other layer’s functions

Objectives





Network TopologiesNetwork topology is the layout pattern of interconnections of the various elements of a computer network.



Network TopologiesPhysical topology means the physical design of a network including the devices, location and cable installation.



Basic topology types This classification is based on the interconnection between computers be it physical or logical.



Basic topology types

Bus Topology In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the MAC address or IP address on the network that is the intended recipient.




Star Topology In local area networks with a star topology, each network host is connected to a central hub. In contrast to the bus topology, the star topology connects each node to the hub with a point-to-point connection. All traffic that traverses the network passes through the central hub.




Ring Topology A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring.




Mesh Topology

The value of fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed's Law.




Tree Topology Also known as a hierarchy network. The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy with a point-to-point link between each of the second level nodes and the top level central 'root' node, while each of the second level nodes.



http://en.wikipedia.org/wiki/File:NetworkTopology-Tree.png



OSI Model

The Open Systems Interconnection model (OSI model) was a product of the Open Systems Interconnection effort at the International Organization for Standardization.

It is a way of sub-dividing a communications system into smaller parts called layers. Similar communication functions are grouped into logical layers.



OSI Layers

Physical Layer The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium.

It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers.



OSI Layers

Data Link Layer

The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

• Link establishment and termination• Frame traffic control• Frame sequencing• Frame acknowledgment Frame delimiting• Frame error checking



OSI Layers

Network Layer The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:

• Routing• Subnet traffic control• Frame fragmentation• Logical-physical address mapping• Subnet usage accounting



OSI Layers

Transport Layer

The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.



OSI Layers

Session Layer

The session layer allows session establishment between processes running on different stations. It provides:

Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.

Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.



OSI Layers

Presentation Layer

The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.



OSI Layers

Application Layer

The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:

• Resource sharing and device redirection• Remote file access• Remote printer access• Inter-process communication• Network management• Directory services• Electronic messaging (such as mail), Network virtual terminals.



Education

Conceptos basicos de redes