Chapter 2 Flashcards
(OSI)stands for what? p28
Open Systems Interconnection (OSI)
is the process of encoding data as it goes down the OSI stack. p28
Encapsulation
is a conceptual blueprint of how communications should take place. It addresses all the processes required for effective communication and divides these processes into logical groupings called layers. p28
reference model
If they’re developing a protocol for a certain layer, all they need to concern them- selves with is that specific layer’s functions, not those of any other layer.The technical term for this idea is called?p29
binding
Advantages of using the OSI layered model include, but are not limited to, the following: p29
It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.
It allows multiple-vendor development through standardization of network components.
It encourages industry standardization by defining what functions occur at each layer of the model.
It allows various types of network hardware and software to communicate
It prevents changes in one layer from affecting other layers, so it doesn’t hamper development and makes application programming easier.
The OSI model has seven layers: p30
Application (Layer 7) Presentation (Layer 6) Session (Layer 5) Transport (Layer 4) Network (Layer 3) Data Link (Layer 2) Physical (Layer 1)
Provides a user interface
Application
Presents data
Handles processing such as encryption
Presentation
Keeps different applications’
data separate
Session
Provides reliable or unreliable delivery
Performs error correction before retransmit
Transport
Provides logical addressing
which routers use for path determination
Network
Combines packets into bytes and bytes into frames
Provides access to media using MAC address
Performs error detection not correction
Data Link
Moves bits between devices
Specifies voltage, wire speed,and pin-out of cables.
Physical
After all of this required synchronization takes place, a connection is fully established and the data transfer begins. This virtual circuit setup is called?p34
overhead.
What is a flow control?p35
Flow control provides a means for the receiver to govern the amount of data sent by the sender.
What are some of the Flow Control protocols involved ensure that the following will be achieved: p35
The segments delivered are acknowledged back to the sender upon their reception
Any segments not acknowledged are retransmitted
Segments are sequenced back into their proper order upon arrival at their destination
A manageable data flow is maintained in order to avoid congestion, overloading, and data loss
what happens when a machine receives a flood of datagrams too quickly for it to process? It stores them in a memory section called a what?p35
Buffer
To summarize, a service is considered connection-oriented if it has the following characteristics: p36
A virtual circuit is set up (such as a three-way handshake).
It uses sequencing.
It uses acknowledgments.
It uses flow control
The quantity of data segments (measured in bytes) that the transmitting machine is allowed to send without receiving an acknowledgment for them is called.p37
window
a technique that requires a receiving machine to communicate with the transmitting source by sending an acknowledgment message back to the sender when it receives data. p38
positive acknowledgment with retransmission
The following network devices operate at all seven layers of the OSI model:p39
Network management stations (NMSs)
Web and application servers
Gateways (not default gateways)
Network hosts
These devices manipulate mainly the physical aspects of a network data stream (such as the voltages, signal direction, and signal strength). The most popular of these are the following:p39
Network Interface Cards (NICs)
Transceivers
Repeaters
Hubs
What is a Network Layer.p39
manages device addressing, tracks the location of devices on the network, and determines the best way to move data, which means that the Network layer must trans- port traffic between devices that aren’t locally attached.
Two types of packets are used at the Network layer: p40
Data packets
Route-update packets
What are some points about routers that you should definitely commit to memory: p41
Routers, by default, won’t forward any broadcast or multicast packets
Routers use the logical address in a Network-layer header to determine the next hop router to forward the packet to.
Routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface
Routers can provide Layer 2 bridging functions if needed and can simultaneously route through the same interface.
Layer 3 devices (routers, in this case) provide connections between virtual LANs (VLANs).
Routers can provide quality of service (QoS) for specific types of network traffic
provides the physical transmission of the data and handles error notification, network topology, and flow control.p42
Data Link layer
The Data Link layer formats the message into pieces, each called p42
data frame
The IEEE Ethernet Data Link layer has two sublayers:p43
Media Access Control (MAC)
Logical Link Control (LLC)
Physical layer, which does two important things: p44
It sends bits and receives bits
