Network layer 3 notes

a dev diary update

frames

mac address for each device

address specific piece of hardware

network interface controller

mac address should be globally unique

Purely layer 1 bad because there's no media access control

Corrupts both.

Controlled

Part 2 Data layer

Now we are layer 2, frame 1

[[architecture-1-data-link.excalidraw]]

there's now a stream of "frames" where we're constantly telling physical layer what to do

ENCAPSULATION

Putting data inside a frame.

Payloads EXTRACTED from the frame ![[architecture-1-data-link.excalidraw]]

OSI MODEL REVIEW

Data link layer only knows connection between the TWO MAC ADDRESSES

CD == Collision Detection

Same concept as detecting race conditions probably...??a

Mac address table

| MAC ADDRESS | PORT | | --------------- | ---- | | e93eu812u9e8u12 | 1234 | | 1981e2ue9812ue | 1235 | | 1902ei9102ie | 1236 | | e01982ue8192eu | 1237 | | | |

  • Identifiable devices
  • Media access control
  • Collision DETECTION
  • Unicast
  • Broadcast 1:n (1 to all)
  • Switches - like Hubs with "super powers"

Device to device communication

So ![[data-link-layer 2024-12-20 19.06.30.excalidraw]]

I'll start with what the situation was at the company and go from there. So there's a problem that happens when layer 2 is across the united states. We need to follow the same protocols or have a really long ethernet chord.

I need to connect the two layers together. I need to be able to know how to transmit across the country in lowest cost possible.

Engineers (over decades) shall create internet (inter -connected network) to create abstraction layers?

now can have access to the data layer 2

![[data-link-layer 2024-12-20 19.13.20.excalidraw]]