[Type text]

7. Application

6. Presentation

5. Session

4. Transport

3. Network

2. Data Link

1. PhysicalPDU: bits

Notes: different media (copper, fiber, wireless) advantages/disadvantages of each kind. When to use ST/Cross? And how to tell the difference between them.

Protocols:

TCP UDP

OSI Reference Model

• This layer serves as the source and destination of communications across data networks.

• Directly accessing the underlying processes that manage and deliver communication to the human network.

• Enabling users to interact with the data network in a way that is meaningful and effective.

Dividing data received from an application into segments Adding a header to identify and manage each segment Using the header information to reassemble the segments

back into application data Passing the assembled data to the correct application Enabling data to be directed to the correct application

running on end devices using port numbers.

Carrying data from one host to another regardless of the type of data.

Layer 3 IP routing does not guarantee reliable delivery or establish a connection before data is transmitted. This connectionless and unreliable communication is fast and flexible, but upper layers must provide mechanisms to guarantee delivery of data if it is needed.

Preparing Network layer packets for placement onto the physical media that transports data.

Encoding the bits for transmission and decoding them at the destination.

Describing the physical, electrical, and mechanical characteristics of the physical media and connectors that interconnect network devices.

PDU: Data Stream

Protocols:

DNS: used to resolve Internet names to IP addresses.

HTTP: used to transfer files that make up the Web pages of the World Wide Web.

SMTP: used for the transfer of mail messages and attachments (MUA MTA, MTA MTA)

POP: mail delivery protocols. They deliver e-mail from the e-mail server (MDA) to the client (MUA)

Telnet: terminal emulation protocol used to provide remote access to servers and networking devices.

PDU: Segment

PDU: PacketProtocols: IPv4, IPv6

Notes:

L3 uses logical addresses to identify and route traffic from one network to another.

Network/subnet address. Broadcast address. Host address. Subnet mask.

Public vs. private addresses Default Gateway Purpose of the routing table

PDU: Frame

Notes:

L2 uses physical addresses to identify nodes and deliver frames in the local network/segment.

Ethernet is the most widely used LAN technology. CSMA/CD, CSMA/CA, Token passing