The OSI Model

Layer 1

Physical Layer #

Layer 2

Data Link Layer #

Layer 3

Network Layer #

Layer 4

Transport Layer #

Layer 5

Session Layer #

Layer 6

Presentation Layer #

Layer 7

Application Layer #

Application Layer (Duties)

Provides Interface between software applications and network for interpreting application requests and requirements.

*Note: This layer is not the actual software application.

Presentation Layer (Duties)

Allows hosts and applications to use a common language; performs data formatting, encryption, and compression.

Session Layer (Duties)

Establishes, maintains, and terminates user connections.

Transport Layer (Duties)

Ensures accurate delivery of data through flow control, segmentation and reassembly, error correction, and acknowledgement.

Network Layer (Duties)

Establishes network connections; translates network addresses into their physical counterparts and determines routing.

Data Link Layer (Duties)

Packages data in frames appropriate to network transmission method.

Physical Layer (Duties)

Manages signaling to and from physical network connections.

Application (Protocols and Standards)

BOOTP, DHCP, DNS, FTP, HTTP, HTTPS, IMAP4,PING, POP3, NSLOOKUP, NTP, SFTP, SMTP, SNMP, Telnet, TFTP

Presentation (Protocols and Standards)

MIME, SSL, TLS

Session (Protocols and Standards)

NetBIOS, PPTP, RPC, SMB, SDP, SCP

Transport (Protocols and Standards)

TCP & UDP

Network (Protocols and Standards)

ARP, ICMP, IGMP, IP, IPSec, RARP

Data Link (Protocols and Standards)

L2TP, PPP, PPTP, SLIP

Physical Link (Standards)

Ethernet (physical), USB, Bluetooth, RS-232, DSL, Fiber, Wi-Fi, NFC