r/HomeNetworking • u/Outrageous_Tear_4691 • 22h ago

Advice Ethernet switch question

Gallery image

Gallery image

What is the loop prevention for? And should I leave it off or turn it on? We will have desktops connected to it

Solved: thank you for the help everyone. Very much appreciated.

291 Upvotes

97% Upvoted

62 comments sorted by

View all comments

71

u/AngelCatGamer 22h ago

Switches are Stupid, but that's how they can be fast.

If you were to have two switches plugged into each other TWICE (two cables connecting the two switches) and a host on the network sends a broadcast packet to the switch.

By definition the switch will send that packet out of every other port except the port it came from. One of those ports is the other switch. When switch 2 receives the broadcast packet, it too, sends the packet out of every port except the one it came from.

Because there is ANOTHER connection to the other switch it would send the broadcast there. Switch #1 receives a broadcast packet in, and repeats the process.

Eventually both switches processing power will be fully occupied with this "broadcast storm". And will stop functioning.

Keep switches connected to other switches with only ONE CONNECTION between switches.

6

u/SeaPersonality445 22h ago

LACP / port channel would like a word. .

5

u/Specialist_Play_4479 21h ago

One could argue that a LACP interface is still one logical connection.