Zusammenfassung der Ressource
TCP/IP Layer 4 Protocols
- Features
- Multiplexing using ports
- Function that allows receiving hosts to choose
the correct application for which the data is
destined, based on the port number.
- IP address,Transport
protocol, Port number
(10.1.1.2, TCP, port
80)
- Hosts typically
allocate dynamic
port numbers
starting at 1024
because the ports
below 1024 are
reserved for
well-known
applications.
- 20
- TCP, FTP data
- 21
- TCP,FTP control
- 22
- TCP, SSH
- 23
- TCP, Telnet
- 53
- UDP, TCP, DNS
- TCP for Zone Transfer
UDP for DNS Queries
- 25
- TCP, SMTP
- 67,68
- UDP, DHCP
- UDP port 67 for sending data to the server,
and UDP port 68 for data to the client
- 69
- UDP, TFTP
- 80
- TCP, HTTP (WWW)
- 110
- TCP, POP3
- 161
- UDP, SNMP
- 443
- TCP, SSL
- Error recovery (reliability)
- Process of numbering and
acknowledging data with Sequence
and Acknowledgment header fields.
- Flow control using windowing
- Process that uses window sizes to protect
buffer space and routing devices from being
overloaded with traffic.
- Connection
establishment and
termination
- Process used to initialize port
numbers and Sequence and
Acknowledgment fields.
- Ordered data
transfer and data
segmentation
- Continuous stream of bytes from an
upper-layer process that is “segmented”
for transmission and delivered to
upper-layer processes at the receiving
device, with the bytes in the same order.
- Transmission Control Protocol
- Provides error recovery
- Relies on IP for
end-to-end delivery of
the data, including
routing issues
- using 2 bits inside the
flag fields of the TCP
header. Called the SYN
and ACK flags
- SYN means
“synchronize the
sequence numbers”
- a three-way handshake
must complete before data
transfer can begin.
- SYN, DPORT=80, SPORT=1027
SYN, ACK, DPORT=1027, SPORT=80
ACK, DPORT=80, SPORT=1027
- TCP Connection Termination
- Four-way termination sequence
- Connection-oriented protocol
- Requires an exchange of messages before data transfer
begins, or that has a required preestablished correlation
between two endpoints
- User Datagram Protocol
- Does not
perform error
recovery
- Connectionless protocol
- Does not require an exchange of
messages and that does not
require a preestablished
correlation between two endpoints
- QoS
- Bandwidth
- The volume of bits per second needed for the application to work well
- Delay
- The amount of time it takes one IP packet to flow from sender to receiver
- Jitter
- The variation in delay
- Loss
- The percentage of packets discarded by
the network before they reach the
destination, which when using TCP, requires
a retransmission.