Network +

OSI Model

Physical Layer
- It is the connents like Cat 6 RJ45 and fiber.
- Its the on and off on the cables.

Data Link Layer.
- Packagers data int frames and transmits those frames on the network.
- Layer 2 devices view nteworks logically.
MAC Address
- Media Access Control
- Physical addressing system of a device which operates on the logial topology.
- Uses a 48-bit address assigned to a network interface card.
- EX: D2:51:F1:3A:34:65
- D2:51:F1 is the vedor code
Logical Link Control
- Provides connection services and allows acknowledgemnt of receipt of message.
- Is the basic form of flow control.
- Provides basic error control functios.
- Uses a check sum.
How communication synchronized.
- Isochronous
  - Netwok devices use a common reference a common refernce clock source and create time slots for transmission.
- Synchronous
  - Network devices agree on clocking method to indicate beginning and end of frames and can use control characters.
- Asynchonous
  - Network devices reference thier own internal clocks and use start and stop bits
What Devices are layer 2
- network cards
- Briges
- Switch
- MAC Address

Network Layer
- Forwards traffic (routing) with logical address.
- IP address IPv4 IPv6
- Logical addressing
  - Ip Addressing IPv4 and IPv6
- Switching (Routing)
- Route discovery and selction
- Connection Services
- Banwidth usage
- Multiplexing
How should data be forward or routed
- Packet Switching (Most common)
  - Data is divided into packets and then forwarded to is IP address.
- Circuit Switching
  - Dedicated communication link is establed between two devices.
  - It uses one path when the connect establed and the whole time the connect is there.
- Message Switching
  - Data is divided into messages which may be stored and then forwarded.
Route Discovery and Selection
- Manually configured as a static route or dynamically through.
Connection Services
- Augment Layer 2 connection services to improve reliability
- Flow Control
- Packet reordering
Internet Control Message Protocol
- Sends error messages and operational information to an IP destination.
  - Ping
  - Trace Route tracert
Devices
- Routers
- Multilayer switches
Protocol
- IPv4
- IPv6
- ICMP