Does Access Point acts as a HUB or SWITCH

[Zaheer_Assariya]

I am using 1200 series AP for 30 nodes. I wanna know what will be the bandwidth for each node (dedicated).

And AP acts as a hub or switch

[scottmac]

On a per-SSID/VLAN basis, it acts as a hub .... a hub that does CSMA/CA (collision avoidence).

Some of the other features (like VLANs) and the BVI interface make it more switch-like.

If you have to put it in a single category, call it a hub - the bandwidth is shared amongst all clients associated with that AP, and only one can talk at a time (per band).

FWIW

Scott

[jesusespinoza]

An AP is a share medium, therefore it acts like a hub and every device compite for the bandwidth in it. Each AP has several contentions methods, such CSMA/CA, RTS/CTS (Request to Send / Clear to Send wth ACK) and Polling, but not all the AP's have this three features, at least the two first.

Now, refering to the quantity of nodes for each AP is so crucial ecause you have to now the kind of traffic is going to pass through that AP, in many case Internet and light web base aplications.

However, bandwidth it's not the same as throughput. Bandwidth is the width of the chanell the comunication goes, for example a bandwitdh of 11 Mbps in 802.11b standar equipment, but the througput for this equipment is 5.5 Mbps, equal to 1X of Data Rate.

If you have a 802.11g equipment or AP at 54 Mbps of Bandwidth the Througput for this equipment will be about 27 Mbps equal to 5X.

In that cases you have a maximun (theoricaly) of 10 to 15 Pc's per AP to guarranty a good performance.

In the oder hand, you have to monitoring the implantation of your AP for that quantity of nodes.

Good Luck and read more about design in wireless Lan... it's just a piece of advise.

[Zaheer_Assariya]

Dear jesusespinoza ,

If AP acts as a hub then will it be right to say that only one pc can communicate with other pc via AP at a time?

And for every message there is only broadcast and no such thing as unicast.( Thats what hubs do right.....repeats the signal out of all ports).

Appriciated & Thanks

[crhyde]

Hi Zaheer:

A hub is an Ethernet device that, as you say, repeats a signal arriving on one port out all other ports. The hub, or repeater, restores the signal strength, regenerates the Ethernet preamble, and retimes bit boundaries.

Whether a frame, Ethernet or WiFi, is considered broadcast or unicast, has to do with its destination address field and not with how a network concentrator forwards or filters the frame. This being said, an Ethernet repeater filters nothing. An Ethernet bridge, or switch, may filter based on destination address.

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.

I hope this helps.

Thanks. /criss

[Zaheer_Assariya]

Dear Criss,

Your answer was very helpull and complete.

Thanks