Week 3 Transport Layer Flashcards
Transport Layer
Allow traffic to be directed to specific network applications
Application Layer
Allows these applications to communicate in a way to understand
Port
16-bit number that’s used to direct traffic to specific services running on a network computer
TCP segment
Made up of a TCP header and a data section
Destination port
The port of the service the traffic is intended for
Source port
A high level port chosen from a special section of ports known as ephemeral ports
Sequence number
32 bit number that used to keep track of where in a sequence of TCP segments this one is expected to be
Acknowledge number
The number of the expected segment
Data offset field
4 bit number that communicates how long the TCP header for the segment is
TCP window
Specifies the range of sequence numbers that might be sent before an acknowledgement is required
Checksum
16 bit, once all segments has been ingested by recipient it is calculated across the entire segment and is compare with checksum header to make sure there is no data lost or corruption
Urgent pointer field
Used in conjunction with one of the TCP control flags to point out particular segments that might be more important than others
Options field
Sometimes used for more complicated flow control protocols
Padding
A sequence of zeros to make sure the data payload begins at the expected location
URG (urgent)
(Control Flag)
A value of one here indicates that the segment is considered urgent and that the urgent pointer field has more data about this
ACK (acknowledged)
(Control flag)
A value of one in this field means that the acknowledgment number field should be examined
PSH (push)
(control flag)
The transmitting device wants the receiving device to push currently buffered data to the application on the receiving end as soon as possible
RST (reset)
( control flag)
One of the sides in a tcp connection hasn’t been able to properly recover from a series of missing or malformed segments
SYN (synchronize)
(Control flag)
It’s used when first establishing a tcp connection and makes sure the receiving end knows to examine the sequence number field
FIN (finish)
(control flag)
When this flag is set to one, it means the transmitting computer doesn’t have any more data to send and the connection can be closed
Handshake
A way for two devices to ensure that they’re speaking the same protocol and will be able to understand each other
Socket
The installation of end point in a potential tcp connection
Instantiating
The actual implementation of something defined elsewhere
LISTEN
(Server side)
A tcp socket is ready and listening for incoming connections
