CH17 Flashcards
(22 cards)
give 2 benefits and 2 drawbacks of packet switching (4)
benefit 1: accuracy - ensures accurate delivery of message
benefit 2: completeness - missing packets can be easily detected and a re-send request sent so the message arrives complete.
drawback 1: requires complex protocols for delivery
drawback 2: network problems may introduce errors in packets
explain how packet switching is used to transfer messages across the internet (5)
- a large message is divided into a group of smaller chunks of the same size called packets.
2.the packet has a header + payload.
- the header contains a source IP address, destination IP address and sequence number.
4.each packet is dispatched independently
5.the packets may arrive out of order
outline the function of a router in packet switching (3)
- the touter examines the packet’s header
2.a router has access to a routing table
- which contains information about the gateway used
state what is circuit switching and state 1 advantage and 1 disadvantage
circuit switching is a dedicated circuit where all the data is transferred over the same route
advantage: data arrives in order so no need to reassemble
disadvantage: less secure since only 1 router is used
state what is packet switching and give 1 advantage and 1 disadvantage
packet switching is when data is split into packets and each packet is given it’s own route
advantage: more secure as harder to intercept messages
disadvantage: time taken to reassemble the packet at destination (since they arrive out of order)
state the function of the HTTPS protocol
for sending receiving web pages
state the function of the IMAP protocol
for downloading emails
state the function of the Transport layer
handles packets
state the function of the internet layer
provides optimal routes for data
state in depth the function of the transport layer (3)
- breaks down data into manageable packets
- adds a packet header
- controls the flow of packets
state in depth the function of the internet layer (3)
- it identifies the intended network and host
- transmits packets to the data link layer
- it routes the packets independently through the optimum route
explain why a protocol is used ion communication between computers (2)
protocols set a standard for communication.
they enable communications between devices from different manufactureres
state the names of the TCP/IP protocol stack in order
- Application layer
- Transport layer
- Network layer
- Link layer
Describe the purpose of the IMAP protocol (2)
its used by email clients to retrieve email messages from a mail server
give 2 benefits and 2 drawbacks of circuit switching (4)
benefit 1: whole bandwidth is available
benefit 2: Data arrives in the same order as it was sent
drawback 1: No alternative route in case of failure
drawback 2: the bandwidth can’t be shared
state 2 examples of where it would be appropriate to use packet switching (2)
packet switching is used when it isn’t necessary to use all the bandwidth. E.g: email
give 4 differences between circuit switching and packet switching
- in circuit, data is received in the same order to was sent, while in packet, the data may arrive out of order
- circuit is a simpler process than packet
3.in circuit the whole bandwidth of the channel is used, while in packet switching it can share bandwidth
- data in packet switching is split into packets, in circuit switching message remains intact
what does BitTorrent provide
peer-to-peer file sharing
what’s the purpose of SMTP
its used when sending email messages towards the intended destination
what’s the purpose of IMAP
its used when retrieving email messages from a mail server over a TCP/IP connection
outline the purpose of the Link Layer in TCP/IP protocol suite (2)
to ensure network protocols are followed, and enables connection with the internet
explain the purpose and function of the Application layer in the TCP/IP protocol suite (3)
it interacts directly with user and its used by web browsers
