Why is the network down?

Question

network hardware

Hello, this is the problem.
There is a local area network from 0 to 255 purely L2 with one domain.

Everything worked fine until today, the Internet works, the local network also, but it constantly breaks. Switches are ordinary, not programmable. How can you test the network? Well, it makes no sense to just mess around with ping & route and etc.
In addition to ordinary switches, ordinary routers are also connected from them (like "connecting a new user", generally op.). With the network, the trouble is generally big, but at the same time everything worked, and now the Internet with the local network is constantly falling ... It works for 2 minutes, then after a few seconds it returns to normal.

Is there any software for checking the network or something like that from your personal experience? I don't even know what to do right now... Turn off the switches one by one and try to see the problem or... It just doesn't fit in my head.

Answer 1

With a peer-to-peer network, only extinguish (turn off, break) segments in turn and thus look for what has flown where.
the most common, in practice, options:
- two ends of the patchcord in a switch (loop)
- a hung Chinese router (ddos all broadcasts)
- a burnt network card / port (also lays down the network)