Modem and router communication

[marobrk]

Hello everyone,

So I'm doing a project about the technical specifications of the networking gear and I want to ask you guys.

How does a router split the signal coming from the modem into multiple devices without having the signals coming to/from the devices mix themselves up.

[Lurick]

To keep it simple, it keeps a table of MAC addresses and MAC to IP mappings for all devices it sees.

Each port is a point-to-point link, more or less, and the router knows what IP address(es) lives off each port.

[marobrk]

So does each device have a different frequency or amplitude or is it purely based on the addresses?

[Lurick]

5 minutes ago, marobrk said:

So does each device have a different frequency or amplitude or is it purely based on the addresses?

Based completely on IP address.

The packet comes in with a destination IP address, the router does it's thing with decapsulating, stripping off the source and destination MAC, doing address lookup, and re-encapsulating the packet with it's MAC as the source and the looked up addresses MAC as the destination, and then sends it out the port that it knows the device lives off, if it doesn't know then it broadcasts a packet out all ports saying "Who has this address" and when a device responds with "Me" then he adds that to his tables. Depending on what's down the line the device will either get it directly and process the packet, or the switch or next device in the line will do another decap of the packet, lookup for the IP address, re-encap the packet with a new source/destination address, and keeps going.

[marobrk]

This should be a good enough explanation.

Thank you very much, your information was very helpful