week 10 Flashcards
(34 cards)
what is the role of the transport layer
–> it is the link between the application layers and the lower layers that are responsible for network transmission
–> The transport layer is responsible for establishing a temporary communication session between 2 applications and delivering data between them.
what are the 2 protocols the transport layer uses to deliver data between applications
- -> transmission control protocol (TCP)
- -> User datagram protocol (UDP)
what are the primary responsibilities of the transport layer protocols
–> tracking the individual communications between applications on the source and destination hosts
–> segmenting data for manageability and reassembling segmented data into streams of application data at the destination
–> identifying the proper application for each communication stream
the transport layer is the link between the application layer and the which is responsible for _____________
network transmission
what is conversation multiplexing
- -> the transport layer divides the data into segments that are easier to manage and transport
- -> multiple applications can use the network at the same time
why is the data in the transport layer broken into segments
- -> easier to manage and transport
- -> allows for conversation multiplexing
- -> facilitates data transport by the lower network layers
- -> error checking can be performed on the data in the segment to check if the segment is changed during transmission
- -> the transport layer also ensures that with multiple applications running on a device, all applications receive the correct device
characteristics of transmission control protocol (TCP)
- -> provides reliable delivery by retransmitting lost of corrupt data
- -> makes larger demands on the network (more overhead)
- -> connection oriented protocol - creates a session between source and destination
- -> it is a stateful protocol as it tracks the session
- -> provides for flow control as it regulates the amount of data transmitted
- -> ordered data reconstruction which reconstructs ordering and sequencing of segments
- -> uses acknowledged delivery and other processes to ensure delivery
characteristics of UDP
- -> provides teh basic functions for delivery
- -> connectionless
- -> unreliable data
- -> no ordered data reconstruction
- -> no flow control
- -> stateless protocol
- -> less overhead
how do application developers choose between TCP and UDP?
–> since there is a trade-off between reliability and the burden it places on the network, developers choose based on the requirements of their application
what are the required properties for streaming video / ip telephony
- -> fast
- -> low overhead
- -> does not require acknowledgements
- -> does not resend lost data
- -> delivers data as it arrives
what are the required protocol properties for smtp/pop or http
- -> reliable
- -> acknowledge data
- -> resends lost data
- -> delivers data in order sent
what do tcp and udp use to differentiate between applications
port numbers
what is a socket
–> a combination of source and destination ip addresses and source and destination port numbers is called socket
–> used to identify the server and service which is requested by the client
what is a socket pair
- -> consists of source and destination ip addresses and port numbers
- -> it is unique and identifies the specific conversation between 2 hosts
_________ assigns the port numbers
internet assigned numbers authority
what are the 3 types of ports
- -> well known ports
- -> registered ports
- -> dynamic / private ports
what is a well known port
- -> ports with numbers (0 to 1023)
- -> reserved for commonly used services and applications
- -> eg are HTTP, SMTP, TELNET
what are registered port numbers
- -> numbers are from 1024 to 49151
- -> assigned to user processes or applications
- -> primarily individual applications user has chosen to install
what are dynamic / private ports
- -> numbers from 49152 to 65535
- -> assigned dynamically to client applications when a client initiates connection to a service
what is the TCP 3 way handshake
- -> the initiating client requests a client to server communication session with the server (SYN)
- -> the server acknowledges the client server communication session and requests a server to client communication session (SYN ACK)
- -> the initiating client acknowledges the server to client communication session (ACK)
what are the fields that contain control information within TCP segment header
ACK => acknowledgement field significant
RST => reset the connection
SYN => synchronize sequence numbers
FIN => No more data from the sender
what are the steps in TCP session termination
–> when the client has no more data to send in the stream, it sends a segment with the FIN flag set
–> the server sends an ACK to acknowledge the receipt of the FIN to terminate the session from client to server
–> the server sends a FIN to the client, to terminate the server to client session
–> the client responds with ACK to acknowledge the FIN from the server
why are segments resequenced in tcp
- -> segments may arrive at their destination out of order
- -> the data in these segments are reassembled into the original order using sequence numbers
___________ and ____________ are used to confirm the receipt
acknowledgment(ACK) and sequence number(SEQ)
