CCNA Fastpassp

• Application (Layer 7)
• Presentation (Layer 6)
• Session (Layer 5)
• Transport (Layer 4)
• Network (Layer 3)
• Data Link (Layer 2)
• Physical (Layer 1)

• Process/Application
• Host - to - Host
• Internet
• Network Access

• Application
• Presentation
• Session

Host-to-Host

Network

• It divides the network communication process into smaller and simpler components,
• thus aiding in component development, design, and troubleshooting.

It allows multiple-vendor development through the standardization of network components.

It encourages industry standardization by defining what functions occur at each layer of the model.

It allows various types of network hardware and software to communicate.

It prevents changes in one layer from affecting other layers, so it does not hamper development.

• 7 layers
• 2 groups
• Upper Layer & Lower Layer

physical layer handles physical topology i.e. moving bits between devices, specifying voltage, wire speed and cable pin-outs

data link layer handles framing i.e. it combined packets into bytes and bytes into frames; it provideds access to media via MAC addresses; performs error detection but not correction

network layer handles routing i.e. provides logical addressing and routing path determination

transport layer handles end to end connection i.e. it provides reliable and unreliable delivery and performs error correction before retransmission

the session layer handles dialog control i.e. it keeps different applications data separate

presentatin layer handles data encryption, compression and translation services i.e. it presents data and handles processes such as encryption

the application layer handles file, print, messaging, database and application services i.e. provides user interaface

• TCP - transmission control protocol
• UDP - user datagram protocol

• takes large blocks of information from an application & breaks them into segments.
• numbers & sequences each segment a
• after these segments are sent waits for an acknowledgment of the receiving end's
• TCP virtual circuit session, retransmitting those that aren't acknowledged.

• a sender's TCP stack contacts the destination's TCP stack to establish a connection called a virtual circuit.
• during initial handshake, 2 TCP layers agree on window size before the recipient's TCP sends ack