OSI model

physical, data link, network, transport, session, presentation, application
encapsulation
Five layers in Internet: physical, data link, network, transport, application (including presentation and session layers of OSI model),

TCP/IP sits in kernel of operating system. packet is passed from RAM to the network card, then through the ethernet cable.

There is a specific bus for tcp/ip between ram and NIC

^ Data link and physical layer.

NIC rejects ehternet packets which aren't adresse to them. you can modify them to add a promoscuous mode which accepts all packets.

you can configure the swtich to send the packets to only the correct address

Network Layer ≡ IP layer

Port number distinguishes addresses at the transport/application layer.

ARP - to find destination MAC address given IP address

send broadcast message to everyone - who had this IP address? What is your MAC address
the store the results of the MAC:IP pairing
sudo arp -a list arp pairings

Journey of IP packet.

routing table created - manual or dynamic. DNS, etc

TCP IP moves the data - there are more protocols within the TCP IP layer that help it to work better.

Questions

what is a gateway
- connected to the same LAN
- when ip is created it will check this table
- LAN can have more that one gateway