M6 DAY 2 Flashcards
The model uses a layered approach to describe networking as a series of tasks that form the communications process.
OSI model
is the interface between the user’s application and the network when the user’s network-aware application requires network resources to accomplish a task.
PDU = data
Application Layer (Layer 7)
are code written by programmers that allow an application to call upon other resources, such as those available on a network and those protected operating system services.
application programming interfaces (APIs).
is a unit of information passed as a self-contained data structure from one layer to another on its way up or down the network protocol stack.
Protocol Data Unit (PDU)
is responsible for presenting the data at the destination with the same meaning and appearance as it had at the source. For outgoing communications, this layer converts data received from the Application Layer into a generic format that survives network transmission. For incoming data, this layer converts the generic representation of data into a format that makes sense to the receiving application.
PDU = Data
Presentation Layer (Layer 6)
sets up, coordinates,and terminates conversations, exchanges,and dialogues between devices across a network. Applications at either end of the session exchange data for as long as the session lasts. Sessions are set up so that they are simplex, half-duplex, or full-duplex.
PDU = Data
Session Layer (Layer 5)
Communications occur in only one direction.
Simplex
Communication occur in two directions but not at the same time.
Half-duplex
Communications occur in two directions simultaneously.
Full-duplex
is responsible for breaking this data into segments, which are pieces small enough to transmit. Each piece is given a sequence number, so the original data is reassembled in proper order after being received by the destination.
PDU = Segment
Transport Layer (Layer 4)
is responsible for the logical addressing and routing of messages to their proper final destination. Logical addressing is applied to each packet, and packets are passed down to the Data Link Layer. Routed protocols and their associated addressing schemes operate in this layer as well as routing protocols.
PDU = Packet
Network Layer (Layer 3)
Routers
provides a reliable method of transmitting data across the communication link. Is broken up into two sub layers called the Logical Link Control (LLC) and the Media Access Control (MAC).
PDU = Frame
Data Link Layer (Layer 2)
switches
NIC
Upper sub layer and handles error checking and flow control between the sender and receiver across a network. This sub layer is also responsible for communicating with the Network Layer.
Logical Link Control (LLC)
Lower sub layer and is responsible for mapping between logical and physical addressing and access to the network media.
Media Access Control (MAC).
is where communications between devices actually take place.
PDU = bit
Physical Layer (Layer 1)
Cables NIC antenna hub repeater
802.3
Ethernet
802.11
Wireless
IEEE 802.2
expanded the OSI model and provided for the LLC and MAC sub layers of the Data Link Layer.
The protocols within the suite are categorized into four layers that correspond directly to the seven layers of the OSI networking model. These layers are Application, Transport, Internet, and Network Interface.
TCP/IP Protocol Suite
each device (computer, router, or other device)with a connection to the network
TCP/IP services primarily operate in the client/server model.
host
makes it easy to pass data between two or more LANs or across WAN links.
routed network protocol
provides the interface between a computer and the network medium. It prepares, sends, and controls data flow across the network. It establishes a physical link to the networking media, generates signals that traverse the network media, and receives incoming signals.
network interface card (NIC)
light emitting diodes (LEDs) of various colors, each meaning something different about the current connection.
link lights
The loss of signal intensity over distance
attenuation
was originally developed for strengthening a signal to extend transmission distance. The problem with this device is it also strengthens any noise it receives along with the intended transmission.
amplifier
is a device that receives and regenerates a signal. Unlike an amplifier, this device removes any noise by recreating the original transmission. This device also makes it possible to transmit signals over large distances such as those covered by transoceanic cable.
Repeaters
are multiport repeaters that receive a digital signal, regenerate it, and then broadcast that signal to all connected ports. Because of this process, when one device transmits, all other devices connected to the hub receive a copy of that transmission.
All devices connected to a hub are in the same collision and broadcast domain.
Hubs
The goal of a switch is to move frames as quickly as possible to their destinations. Unlike a hub, this device decide on which port to send a signal instead of broadcasting it out every port. This device have independent bandwidth on each port for this purpose. They also are capable of learning addresses, making forwarding/filtering decisions and avoiding loops. It break up (define) collision domains but not broadcast domains.
Switches
interconnects local or wide area networks and is located at the gateway where one network meets another. The primary function of this device is to determine the next network to which a packet is sent by scanning the destination IP address and searching for the best path to get a packet to its destination. This device also provides traffic control and filtering functions when multiple paths are available between two endpoints. It is capable of breaking up both broadcast and collision domains.
Router
To alleviate the need for different cable, vendors developed a method of electronically switching the transmit and receive wires inside the equipment.
uplink port
is used to send traffic to a single host or destination.
Unicast addressing
sends traffic to a group of hosts or recipients.
Multicast addressing
is used to send traffic to all hosts on a network.
Broadcast addressing
maps traffic to the nearest host providing a specific service.
Anycast addressing
a 48-bit (6-byte) hexadecimal address burned into the NIC and used in the delivery of information on an Ethernet network
Media Access Control (MAC) Address