Day 1 Studying for CCNA

I have made up my mind to stay focused on obtaining my CCNA or Cisco Certified Network Associate, I have downloaded many study guides and plan to read one chapter daily, out of my CCNA book. When I pass the exam I will focus on security. I would like to become a expert with firewall technologies, configurations and setup.

The main subject for today is the OSI layer or open systems interconnect. This is a standard that allows vendors software/hardware to communicate. There are seven layers for the OSI model. They include: Application, Presentation, Session, Transport, Network, Data and Physical layers.

The Application layer provides network access to programs, it also does error recovery and flow control. It makes sure that communications can be established by checking resources. The following protocols can be found here. NCP, SMB, Telnet, SMTP, Appletalk and SMB.

The Presentation layer does protocol conversion and my favorite encryption and data compression. This layer uses protocols such as NCP, TDI and AFP.

The Session layer does just that it opens a session it does connection establishment, data transfer and cloese the connection. The protocol NetBios can be found on this layer.

The Transport layer put messages into smaller packages adn does error detection and correction. Some of the protocols here NetBeui, NWLink, IP, IPX, and TCP.

The Network Layer does routing, handles addressing, translates logical addresses to physical ones as well as traffic management. The protocols here are IP, IPX, NWLink and NetBeui.

The Data Link Layer packages bits into frames so they can be transported over the network layer. There is also the MAC sublayer that puts the MAC address into the frame header.

The Physical Layer would bethe actual cabling, connectors and electrical signals transmitted on the wire.

That is my quick synopsis of the OSI layer.