Transport Layer Flashcards
ports
network sockets, TCP & UDP, what application plug into to listen and receive communication over the network, allow multiple applications to run on a single machine
port range
1 - 65535 (16-bit)
well-known ports
0-1023
DNS
53
SSH
22
FTP
20, 21
registered ports
1024-49151
MySQL
2206
Skype
23399
registering ports
0-49151 can be registered through IANA
dynamic ports
49152-65535, used as temporary source port from PC, eventually times out
segmenting
sending - chop it up; receiving - reassemble, segment size determined by data link layer protocol, that size is shared as part of the TCP handshake
sessions
connection: think phone conversation; connectionless: think sending a letter
sequence numbers
part of TCP, but not part of UDP
reasons for not using sequence numbers
when old info is no longer needed, when the delay to retransmit isn’t worth the effort (video calling), when you don’t need every single bit
UDP
User Datagram Protocol, connectionless, no flow control
TCP
Transmission Control Protocol, connection-oriented, 3-way handshake, sequence numbers
UDP header
64 bits in size, source and destination ports, length of the datagram, checks for errors
TCP header
160 bits in size, source port, destination port, sequence number, acknowledgment number, other data
sliding window
TCP’s way of doing flow control
QUIC
used by Google; provides some features of TCP over a UDP connection
TCP users
HTTP, email, file transfers
DNS users
video conferencing, DNS
