OSI Layers

OSI (Open System Interconnections Reference Model) layers including 7 layers:
from bottom layer
--------------> To Top layer
->Physical layer - Layer 1 (ISDN, ATM, ADSL, FDDI, Coax)
-> link layer (SLIP, PPP, 802.2, Ethernet)
-> network layer (Internet Protocol 4, IPV6)
->Transport layer (TCP, UDP)
->Session Layer (POP/25, 80, 20/21, 443
->Presentation Layer (POP, SMTP, HTTP, FTP, Telnet, DNS,SNMP, NFS, HTTS)
->Application Layer - Layer 7 (Email, Newsgroup, Web apps, File transfer, host sessions, directory service, network management, file service)