Network Hub -- duplicates ALL traffic to ALL devices ?

finance_teacher used Ask the Experts™
Everyone has always said HUBs are bad and send information to ALL devices

I have an employee that needs another PC setup next to them ASAP and I do not have time to run another 100' CAT6 cable from the switch to this PC, therefore I just setup a small $10 cheap hub as follows

 1. patch cord from SWITCH to HUB
 2. patch cord from HUB to PC #1
 3. patch cord from HUB to PC #2

Which one of the below options will happens since a HUB is now in the mix when PC #2 updates a file on the Windows 2012 R2 file server since I did not wire back to the Cisco switch ?

    ** Option #1 = PC #2 sends info to ALL 100+ devices on my network, with only the file server accepting the data

    ** Option #2 = PC #2 sends info to ALL devices that are plugged into the hub (i.e. only PC #1 and the switch), with only the file server accepting the data

   ** Option #3 = something else ?
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Scott CSenior Engineer

Replace that cheap hub with a cheap switch.  I didn't know they even still made hubs.


Ok, but just for my knowledge, which of the above options will happen currently until I get a cheap switch ?
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

If the Hub is old enough it may need crossover cables or it may not even work in a modern environment. I would replace it with a small switch as stated (Best Buy, some hardware outlets). You can pick one up in an hour or so.
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Scott CSenior Engineer

I believe Option #1 would be the case, but again, it's been forever since I've used a hub.  I've pretty much forgotten all the nuances of them.

I think this would happen because the hub has no routing capabilities.
Option 2 and the speed will top out at 100 mb half duplex between the hub and the switch.

There are very few hubs out there anymore,so any more modern piece of networking equipment from maybe the past 10 or 15 years is probably a switch.

It will not send out packets to any other devices on the network except those on the hub (its collision domain).

The switch port the hub is attached to will segment the hub from broadcasting to any other device (segments collision domains).

A hub is half duplex and will be slower than a switch,but will probably not need any crossover cables because most smart switches will only use one(10 mb ) or 2(100 mb) of the two active pairs of a half duplex hub.

You may see some collisions on the main segmenting port,but I doubt it.

3Com had a term called switched backbone Ethernet and because switches were so expensive back in the day ,using a switch to segment hubs was a preferred architecture for the folks that couldn't afford switches all around.

So in a word,don't worry about it.
Don JohnstonInstructor
Top Expert 2015
Which one of the below options will happens since a HUB is now in the mix
Option #2 is the closest. PC 1 and PC 2 will see all traffic either sends.  The switch will effectively filter any traffic from those devices if the traffic is not destined to the rest of the network.

Traffic sent to the server will be "accepted" by the server as it always was.
Distinguished Expert 2018
Option 2 is what would occur. But given the availability and low cost of unmanaged switches these days, there's really no need to have a hub around. And you wouldn't have to run another cable as you were worried about.

Will having an actual hub around cause all sorts of nightmares for what you're talking about? Honestly, no.
>there's really no need to have a hub around.

Hubs are nice if you have switches that don't do port mirroring when doing packet captures.

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