Hi there.

I was hoping that you could help me with a couple of issues that I'm trying to
get resolved.


Background:
I'm helping out a friend who has a pretty complex home network set-up

Basic network overview:

Enterprise wireless modem/router (using a SIM card and mobile network, for network access) >
Swich 1 >
Switch 2
Switch 3
Swtich 4

Switch / network 2 = security cameras
Switch / network 3 = office / work PCs
Switch / network 4 = guest Wi-Fi

Issue:
They are experiencing very large and (unexplained) spikes in data usage
We are trying to establlish what is causing this.

We have done a veriety of testing and the issue is definately being caused from something
within this interal network infrastructure.

They have a spare PC which they are going to install Wireshark onto
(it currently only has x1 NIC card, and ethernet port)

This PC is going to be connected directly betwen the modem/router and the
1st Switch on the network (to capture as much traffic and throughput as possible).

Enterprise modem/router > Spare PC with wireshark > Switch 1 > Rest of
network


Questions:

1. Do we need a 2nd NIC card installed into the PC, to feed out from the
PC back into the 1st Switch, so that we can capture all of the traffic
on the network ?

2. Or could we instead, use an ethernet splitter with the original NIC card
to give us 2 ethernet ports, and use one of them to connect back into the
1st swtich. Again - to capture all of the network traffic ?

3. Is there anything else that I'm missing to be able to achive this ?

TIA for any help or advice !

Precisely what do you mean by "data usage" and what metric are you using the measure it?

Have you tried top or htop? If so, what applications did they show as top users of memory?

If you can live with a (temporary) downgrade of the Ethernet speed to 100 Mbps and you're willing to do a bit of DIY hacking, you could build yourself a passive Ethernet tap device. Just Google for "Passive Ethernet Tap DIY". With that, you don't have to mess with exotic network configurations, you just insert it at a spot where you expect the unknown traffic to be present. But it allows you to monitor only one direction at a time with Wireshark (half duplex).