A beginner question on Access Point - AP = broadcast ?

[SJ K]

Hi all,

Please pardon me, as this is a beginner question.

As the topic goes,  i am wondering if an AP is really a ( wireless switch) and I do not need a router if the devices connected to the AP only need to communicate to each other (in the same subnet).

I do not have an actual device and is actually doing this setup on packet tracer ->  what i realized is that an Unicast frame (ICMP) from PC1 to PC2 through the AP, is actually Broadcast out. (I am not sure if it is really a broadcast, but what i do see is the AP sending out the Unicast frame to all devices connected to the AP).

Is it normal ?

Does that means AP -> Wireless communication = broadcast  and i can sniff packets/frames destined to other machines ?

Regards,
Noob

[Leo Laohoo · Accepted solution]

A wireless access point is a dumb HUB:  One talks and everyone has to stop, listen, waits for their turn to talk.  This is why we always tell people even though it will say in Data Sheets that a wireless access point can support 1000 wireless clients it ain't a good idea.  

If the wireless clients are just in the same IP address subnet then a Layer 3 device ain't really necessary.  

[SJ K]

Hi Leo,

Thanks for your reply!.

So in fact , the frame is a unicast frame (not a broadcast), but as you mentioned, the AP is behaving like a "Hub"  and thus the unicast frame is send out to all devices - am i right ?

Regards,
Noob

[Scott Fella · Accepted solution]

Like what Leo mentioned, wireless is like a hub and is half duplex.  You have the ability to drop peer to peer or else you would be able to see all devices on the same subnet.  So yes... It sends it out to all devices.

-Scott 

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[mohanak]

Refer link : https://supportforums.cisco.com/discussion/9544896/does-access-point-acts-hub-or-switch

[SJ K]

Hi Mohanak and all,

Thanks for all your replies and sorry for getting back late.

On the link above, I saw this post from crhyde ->

A WiFi access point is neither a hub nor a switch. As you suspect, for any one access point and its associated client stations only one frame may be successfully transmitted at a time and collisions do happen; this is like an Ethernet hub. The access point must receive the entire frame before forwarding it, and forwards or filters based on destination address; this is like a bridge.

Does an access point forward base on destination address ?;  How does it forward base on destination since it is sending out to everyone ?

Regards,
Noob