Switching

Data Link Layer recap
- Provides node-to-note connectivity and data transfer (zb pc to switch, switch to router,…)
- Deefines how data is formatted for transmission over a physical medium (zb copper utp calbes)
- Detects and (possibly) corrects Physical Layer errors
- Uses Layer 2 addressing, seperate from Layer 3 addressing (nix ips) ethernet-frame-aufbau
MAC Address
- 6 byte (48bit)
- physical address asigned to the device when it is made
- AKA “Burned in Address” (Bia)
- unique
- OUI
  - first 3 bytes of the address
  - Organizationally Unique identifier
  - assinged to the company making the device
- last 3 bytes are unique to the deivce itself (Bia)
- written in 12 hexadecimal characters
Example for Frames going through a Switch
More Detailed Example
Arp
- → Address Resolution Protocol
- used to discover Layer 2 adress of a known Layer 3 address
- ARP Request → brodcast = send to all hosts on the network
- ARP Replay → unicast only to one host → the one that requestet it

Quartz 4