User:Becha/InternetPlumbing/Layers

Comparing OSI & TCP / IP layers

Original borrowed from: https://en.wikipedia.org/wiki/OSI_model

TCP / IP Model	OSI Model
Layer	OSI Layer	Protocol data unit (PDU)	Function	Examples
Application	7. Application	Data	High-level APIs, including resource sharing, remote file access, directory services and virtual terminals	TLS, FTP, HTTP, HTTPS, SMTP, SSH, Telnet, BGP!
	6. Presentation		Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption	CSS, GIF, HTML, XML, JSON
Transport	5. Session		Managing communication sessions, i.e. continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes	RPC, SCP, NFS, PAP,
	4. Transport	Segment (TCP) / Datagram (UDP)	Reliable transmission of data segments between points on a network, including segmentation, acknowledgement and multiplexing	NBF, TCP, UDP
Network / Internet	3. Network	Packet	Structuring and managing a multi-node network, including addressing, routing and traffic control	AppleTalk, ICMP, IPsec, IPv4, IPv6
Link layer	2. Data link	Frame	Reliable transmission of data frames between two nodes connected by a physical layer	IEEE 802.2, L2TP, LLDP, MAC, PPP, ATM, MPLS
	1. Physical	Bit	Transmission and reception of raw bit streams over a physical medium	DOCSIS, DSL, Ethernet physical layer, ISDN, USB

Cross-layer functions:

• ARP is used to translate IPv4 addresses (OSI layer 3) into Ethernet MAC addresses (OSI layer 2).
• Domain Name Service is an Application Layer service which is used to look up the IP address of a given domain name. Once a reply is received from the DNS server, it is then possible to form a Layer 3 connection to the third-party host.
• etc

Owners, Developers, Dangers, Mitigations, Alternatives

#	Layer name	Example	Practically	Owner	Developed by	Vulnerabilities/Dangers	Securing	Alternatives
10
9
8
Application layer	7.3 -> skype
	7.2 -> SMTP / email
	7.1 HTTP
6	Presentation	HTML, CSS, JSON
5	Session	BGP (actually layer 7...)	routing: exchanging AS reachability info via gossip: based on trust & peering agreements! physical routers by routers: Cisco/Juniper (commercial monopolists ;-)	Large ISPs; Tier1 / Tier2 ; IXPs!! RIRs give out AS numbers	"routing-wg" @ RIPE; *NOGs! (nano, nlnog, grnog; peering forums; Euro-IX); IETF; Open-Source community ; hackers	"route hijacks", government regulation & takeover (killer switch), hierarchies;	technically: BGPsec, IRR, RPKI; politically: influencing governance	p2p protocols, Betman [xx]; MPLS, SDN; Tor?!
4	Transport	UDP -> DNS	www.belastingdiest.nl	User; Registrar, Registry, ccTLD, gTLD, ICANN, US government!	DNS OARC, IETF, root-nameserver operators, ICANN, IGF/UN/ITU	"balkanisation", US hegemony; internationalization; censorship;	technically: DNSSEC, DANE ; Tor; politically: participating in governance	Alternative trees; blockchain (namecoin); etc
3	Network	Internet	ifconfig; 10.10.10.10, IPv6	no-one: IP addresses are "leased"! (PI,PA,LIR,RIR,IANA,IETF)	RIR PDP, IANA, IETF	hierarchy, run-out, incompatibility, market forces; surveillance	IPSec	Blockchain?
2	Data-link	Physical connections	Ethernet cables, WiFi, fibers, satellites, under-sea cables	Individuals, communities, ISP, "carriers", corporations, governments,	Hackers, commercial companies, governments	"ownership" models; hierarchy of server-client model; pollution & distraction of Earth; surveillance	commoning; shared infrastructure; development of sustainable technologies (?!), recycling; awareness & activism	Community WiFi, Project Loon, Drones
1	Physical	HW - end user equipment	Computer, tablet, phone...	User	Commercial companies: Apple, Siemens, Samsung...	Un-ethical manufacturing, security backdoors, pollution caused by e-waste disposal,	Hard:	Open HW movement; fair-phone; DIY, Repair Cafes, fair-trade...