Ethernet / IP Flashcards
What is IEEE 802 (Ethernet)?
First all computers went through one ethernet cable to connect to internet, but today all computers are connected on the same Switch, that are then connected to the ethernet-cable (one household).
1) Computer A to B
2) Connects several computers to the main cable. All computers a connected to the same medium/wire, that sends the same signal to all computers.
What were the Cons (-) with Ethernet back in the 70s?
- The problem with ethernet is that other computers has to wait when someone else “is talking”.
- It doesn’t scale well, the more computer you have, the more probability it is that is colliding.
- Security problems.
What is a Hub?
A Hub is a networking device that allows you to connect multiple PCs to a single network.
Looks like a router, where you can plug all your wires. But a hub recieves a message, and send it to alle the computers at the same time. Not intellegent.
How do did we use the Ethernet-cable back then, vs now?
Then: Through a Hub (10 Mbits/s - 40 Gbits/s)
Now: Through a Switch (40 Gbits)
What is a MAC address?
A 48-bit address. A fingerprint (a unique identifier) for your device, everyone is unique.
What is an Address Learning?
1) When a packet arrives from M on port K, add to forward table M, K.
2) If an entry for M already exists, overwrite it.
Issues with address learning is that there are too many switch to few computers, so the switch dont know the final destination to the other computers.
What is STP?
Spanning Three Protocol.
A network protocol that builds a loop-free logical topology for Ethernet networks.
What is the difference between an IP and Ethernet?
Ethernet addresses are flat.
IP addresses are hierarchical.
What is an IP-address?
Internet Protocol.
An Internet Protocol address (IP address) is a numerical label such as 192.0.2.1 that is connected to a computer network that uses the Internet Protocol for communication.
An IP address serves two main functions:
Network interface identification and location addressing.
96.168.1.2/16 means?
All addresses of the from 196.168.X.X are in the same network.
62.94.16.80/29 means?
All addresses from 62.94.16.80 to 62.94.16.88 are in the same network.
What does the ICMP program do?
Defines code and tests for error.
- Type 0: Echo (send back message).
- Type 3: Destination unreachable (this IP does not exist in this network).
- Type 11: Time exceeded (path destination is too long, stopping here).
What does Ping do?
Uses ICMP type 0 to test if another host is connected.
What does Tracerout do?
Tells you if you are connected or not.
