Cheat_sheet.md

Protocols' cheat sheet

Abbr.	Name	Layer	Dependecy	Description
HTTP	Hyper Text Transfer Protocol	Application Layer	TCP	Pull Protocol, Web's application-layer protocol is a the heart of the Web. It is implemented in two programs: a client program and a server program.
SMTP	Simple Mail Transfer Protocol	Application Layer	TCP	Push Protocol, Mail: major components: user agents, mail servers, and the Simple Mail Transfer Protocol (SMTP).
FTP	File Transfer Protocol	Application Layer	TCP	-
Telnet	File Transfer Protocol	Application Layer	TCP	-
SIP	Session Initiation Protocol	Application Layer	UDP / TCP	-
RTP	Real-time Transport Protocol	Application Layer	UDP / TCP	-
POP3	Post Office Protocol—Version 3	Application Layer	TCP	Pull Protocol, used in mails (Persistent only)
IMAP	Internet Mail Access Protocol	Application Layer	TCP	Pull Protocol, The IMAP protocol provides commands to allow users to create folders and move messages from one folder to another.({No/Persistent})
DNS	Domain Name System	Application Layer	UDP	translates domains into IP addresses.
TCP	Transmission Control Protocol	Transport Layer	-	reliable, connection-oriented service four-tuple: (source IP address, source port number, destination IP address, destination port number) 20 bytes
UDP	User Datagram Protocol	Transport Layer	-	unreliable, connectionless service two-tuple: (destination IP address , destination port number) 8 bytes
IP	Internet Protocol	Network Layer	TCP	large IP datagram divided (“fragmented”) within net, one datagram becomes several datagrams, “reassembled” only at final destination.
ICMP	Internet Control Message Protocol	Network Layer	-	Error reporting
DHCP	Dynamic Host Configuration Protocol	Application Layer	UDP	host broadcasts “DHCP discover” msg [optional], DHCP server responds with “DHCP offer” msg [optional], host requests IP address: “DHCP request” msg, DHCP server sends address: “DHCP ack” msg
OSPF	Open Shortest Path First	Link Layer	UDP / TCP	uses link-state algorithm, link state packet dissemination, topology map at each node, route computation using Dijkstra’s algorithm
BGP	Border Gateway Protocol	Application Layer	-	-
SNMP	Simple Network Management Protocol	Application Layer	-	request/response mode, trap mode.
MAC	Medium Access Control	Link Layer	-	medium access control (MAC) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium.
Slotted ALOHA	Slotted ALOHA	Link Layer	-	when node obtains fresh frame, transmits in next slot, if no collision: node can send new frame in next slot, if collision: node retransmits frame in each subsequent slot with prob. p until success
Pure (unslotted) ALOHA	Pure (unslotted) ALOHA	Link Layer	-	simpler, no synchronization, when frame first arrives -> transmit immediately, collision probability increases: frame sent at t0 collides with other frames sent in [t0-1,t0+1].
CSMA	Carrier Sense Multiple Access	Link Layer	-	CSMA: listen before transmit:if channel sensed idle: transmit entire frame, if channel sensed busy, defer transmission
Taking turns	Taking turns	Link Layer	-	channel partitioning MAC protocols: share channel efficiently and fairly at high load, inefficient at low load: delay in channel access, 1/N bandwidth allocated even if only 1 active node!
ARP	Address Resolution Protocol	Link Layer	-	ARP table: each IP node (host, router) on LAN has table: IP/MAC address mappings for some LAN nodes: < IP address; MAC address; TTL>, TTL (Time To Live):

Abbreviation's cheat sheet

Abbr.	Name	Description
RFC	Request for comments	-
IETF	Internet Engineering Task Force	-
DSL	Digital Subscriber Line	use existing telephone line to central office DSLAM, < 2.5 Mbps upstream, < 24 Mbps
SSL	Secure Sockets Layer	provides critical process-to-process security services including encryption, data integrity and end-point authentication.
API	Application programming interface	Interface (API) between the application and the network.
ISP	Internet Service Provider	End systems connect to Internet via access ISPs (Internet Service Providers)
TLD	Top - Level Domain	responsible for com, org, net, edu, aero, jobs, museums, and all top-level country domains, e.g.: uk, fr, ca, jp
DASH	Dynamic, Adaptive Streaming over HTTP	divides video file into multiple chunks,each chunk stored, encoded at different rates
CDN	Content Distribution Networks	store/serve multiple copies of videos at multiple geographically distributed sites (CDN)
GBN	Go Back-N	sender can have up to N unacked packets in pipeline,receiver only sends cumulative ack
FSM	Finite State Machine	-
CAs	Control Agents	-
SDN	Software Defined Network	implemented in (remote) servers
HOL	Head of the Line blocking	Overloading in buffers in output buffers
RTT	Round Trip Time	is the length of time it takes for a signal to be sent plus the length of time it takes for an acknowledgement of that signal to be received.
CIDR	Classless InterDomain Routing	is a method for allocating IP addresses and IP routing.
ICANN	Internet Corporation for Assigned Names and Numbers	allocates addresses,manages DNS,assigns domain names, resolves disputes
NAT	Network Address Translation	range of addresses not needed from ISP: just one IP address for all devices can change addresses of devices in local network without notifying outside world
FDM	Frequency Divison Multiplexing	different channels transmitted in different frequency bands
TDM	Time Divison Multiplexing	different channels transmitted in different time slots
MIB	Management Information Base	between server and agent.
CRC	Cyclic redundancy check	more powerful error-detection coding
DOCSIS	data over cable service interface spec	FDM over upstream, downstream frequency channels,TDM upstream: some slots assigned, some have contention