Communicating over the network - part 1 Flashcards
(47 cards)
What are the 3 (7) elements of a communication
Message source/sender (Encoding) (Transmitter) Transmission medium "the channel" (Receiver) (Decoder) Message destination/receiver
Why aren’t single communications (video, email etc…) sent out as a continuous stream of bits? Give 3 reasons
- No other device on the network would be able to send/receive data while the transmission was in progress
- Large data streams would cause significant delays
- If a link in network structure failed during transmission, the whole communication would be lost and would have to be re transmitted in full
What is the alternative to send out a continuous stream of bits and what is it called?
Segmentation - dividing a message into small, manageable pieces to send over the network
What are 4 benefits of segmentation?
- Smaller pieces can be multiplexed; interleaved along the same media meaning multiple messages can be sent at once
- Smaller pieces need not take the same route from source to destination, making the network more reliable
- If one pathway is unavailable, another may be taken
- If parts of a message fail to deliver, only those missing parts need to be retransmitted
What is the downside to segmentation and multiplexing?
The added layer of complexity: each piece of the message needs to be labelled when split apart and then re-assembled at the other end based on those labels.
What are the two physical elements/hardware of a network?
Devices and media
What are the two communications programs/software that run on networked devices?
Processes and services
What does a network service do?
Provides information in response to a request
What are some examples included by network services?
Email hosting services
Web hosting services
What does a network process do?
Processes provide the functionality that directs and moves messages across a network
What are end devices?
The devices that provide an interface between the human network and the underlying communications network
What are some examples of end devices?
Computers (workstations, laptops, file servers, web servers) Network printers VoIP phones Security Cameras Mobile handheld devices
What are end devices referred to as in a network?
Hosts
How does a host device interact with a message in the communication process?
It is either the source or the recipient.
How are host distinguished from one another in a network?
They are identified by an address that the message source uses as a destination for the message.
What can hosts act as in modern networks?
A client, server, or both
What is a server?
A host that has software on that allows it to provide information and services, like email or web pages
What does a server provide services to?
Other hosts on the network
What are clients?
Clients are hosts that have software allowing them to obtain and display information from a server
What is the role of intermediary devices?
They connect individual hosts to a network and can link networks together to form an internetwork
What are some examples of intermediary devices?
Network access devices (hubs, switches, wireless access points) Internetworking devices (routers) Communication servers and modems Security devices (firewall)
What is another role of intermediary devices?
Management of data as it flows through a network
How do intermediary devices manage flow of data through a network?
The devices uses the host address along with information about other connected intermediary devices to calculate a path for the message.
What is the first function from processes running on intermediary devices in a network?
Regenerates and re-transmits data signals
