ICND 1 - Chapter 1

-Source sends a broadcast trying to find out who has the destination IP, using the MAC address-Destination answers and also sends broadcast trying to find out who has Source IP-Source now has IP, Mac, and hostname resolution and can send data

-Too many hosts-Broadcast storms-Multicasting-Low Bandwidth-Adding hubs-Chatty protocols like IPX

-Broadcast domain - Set of all devices on a network segment that hear all the broadcasts sent on that segment.
-Collision domain - Term to describe network scenario in which one machine sends a packet and everyone else is forced to listen to it - collisions occur when another device tries to transmit at the same time (as in hub environment with all devices on same collision domain).

-Routers move packets of data from one network segment to another.-Switches break up collision domains and segment the network

-Break up broadcast domains - do not pass broadcasts to all networks by default.-Can filter network based on layer 3 information like IP

-Packet switching - use logical addressing-Packet filtering - access lists and control-Internetwork communication - connect two or more networks together

-Add functionality to a LAN through optimizing performance-Switch frames from one port to another within the switched network

Implement at least one switch, connect the hubs to the switch as well as the servers - creates 4 collision domains instead of just 1.

-Help vendors create interoperable devices and software through agreed-upon standards and protocols.-Describes how data and network info are communicated from application on one computer to another application on another computer, through respective network media.

Lower Layers (responsible for data being transferred through physical wire or switches/routers, rebuilding of data stream from transmitting host to destination host)(1) Physical (2) Data (3) Network(4) Transport
Upper Layers (responsible for applications communicating with hosts)(5) Session (6) Presentation (7) Application

Moves bits between devices, specifies voltage, wire speed.
Specifies electrical, mechanical, procedural and functional requirements for activating/deactivating a physical link between end systems.

Ex. - Physical topology, Hubs, Bridges

Combines packets into bytes and bytes into frames, provides access to media through MAC address, provides error detection but not correction.
Formats message into pieces called a data frame, adds custom header containing hardware dst. and src. address - encapsulates data.
Responsible for identification of devices in network.
Transmits control information for route that is stripped off with each hop until it is delivered to the correct device.

Ex. - Framing, Switches

Provides logical addressing, which routers use for path determination. Tracks location of devices on the network, transports traffic between devices that aren't locally attached.
When routers receive a packet, destination IP is checked. If IP is not for that router, it will look up the destination network address in the routing table. If no entry, packet is dropped.
Two types - data packets (transporting user data) and route updates (update neighboring routers about networks)
Ex. - Routing, Routers

Provides reliable/unreliable delivery and error correction before re-transmitting, provides logical connection between hosts.
Flow control - prevent sending host from overflowing the butters in the receiving host - provide a means for the receiver to regulate the amount of data sent by sender. Has buffer (stoplight) to send not ready signal to sender if there is flood.
Transmitting device sets up three way handshake (hello, acknowledgement-hello/rules, acknowledgement-begin) - Synchronize to dst., negotiate connection, synchronize to src., acknowledge to dst., data transfer

Ex. - End-to-end connections, TCP, UDP

Keeps different applications separate. Setup, management, and tear down of sessions for Presentation layer entities. Has three modes: simplex, half duplex, and full duplex.
Ex. - Dialog control between devices or nodes.