CCNA 1 Module 9

Responsible for establishing a temporary communication session between two applications and delivering data between them.

Maintain and track multiple conversations (e.g., multiple browser tabs).

Transport layer protocols segment the application data into appropriately sized blocks.

At the destination, the transport layer reconstructs the pieces of data.

Used by the transport layer to identify the target application for data delivery.

Transport layer manages reliability requirements of a conversation.

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Reliable, full-featured transport layer protocol ensuring all data arrives at the destination.

Simple transport layer protocol that does not provide reliability.

Numbering and tracking data segments, acknowledging received data, retransmitting unacknowledged data.

Basic delivery of data segments with minimal overhead and data checking.

Best-effort delivery protocol.

Unreliable delivery since no acknowledgment guarantees reception at destination.

Streaming live audio, live video, and Voice over IP (VoIP).

Connection-oriented protocol.

Negotiates and establishes a permanent connection/session before forwarding traffic.

Numbering and sequencing ensures segments are reassembled in proper order.

Protocol that keeps track of the state of the communication session.

Records which information has been sent and which has been acknowledged.

20 bytes of overhead encapsulating application layer data.

Source Port (16 bits), Destination Port (16 bits), Sequence Number (32 bits), Acknowledgment Number (32 bits), Header Length (4 bits), Reserved (6 bits), Control Bits (6 bits), Window Size (16 bits), Checksum (16 bits), Urgent (16 bits).

Stateless protocol; neither client nor server tracks session state.

Pieces of communication in UDP.

TCP and UDP use headers to uniquely identify applications.

Dynamically generated by sending device to identify a conversation.

Combination of source IP + source port or destination IP + destination port.

0–1023, reserved for common services (web, email, etc.).

1024–49151, assigned by IANA for specific applications.

49152–65535, usually assigned dynamically by client OS.

Three-way handshake: client request, server acknowledgment, client acknowledgment.

FIN control flag set in segment header.

Uses a FIN segment and an ACK segment.

Client sends FIN, server ACKs, server sends FIN, client ACKs.

Presence verification, service availability verification, informs destination of session intent.

Initial sequence number (ISN) is set.

TCP mechanism controlling how much data the destination can reliably receive and process.

Number of bytes the destination device can accept and process at one time.

Overloaded routers discard packets.

Lost segments are retransmitted by source during congestion.

Simple, low-overhead protocol; not connection-oriented; lacks retransmission, sequencing, and flow control.

Reassembles data in order received and forwards to the application.

Live video/multimedia, simple requesteply, applications handling reliability themselves.

Divide application data into segments, add headers, reassemble segments, deliver to correct application.

UDP and TCP.