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Could someone please tell me if Wifi uses routing? If so, why and how?

My idea is the wireless router can simply broadcast, and wireless devices within its range can receive the signal. So, no routing protocols should be involved there.


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migrated from Sep 1 '10 at 0:02

This question came from our site for professional and enthusiast programmers.

Most Wifi devices that I know of contain a router. But what do I know? I'm just a programmer. The folks over at SuperUser might be better able to answer your question. – Robert Harvey Aug 31 '10 at 15:20

Wifi is just a 'blind' physical data transmission protocol it doesn't involve routing anyway (which is done in the Network layer), see OSI stack for more informations.

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Yes, I understood that. I guess the terms "Wifi" and "Wireless LAN" confuses me :) – Barun Aug 31 '10 at 15:43

"Wifi" is a whole class of protocols. The physical layer (i.e. 802.11) does not involve routing, no.

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Thanks, I almost forgot that. – Barun Aug 31 '10 at 15:46

Sure, you don't absolutely need a router. All devices on the same Wifi "service set" (ESSID or BSSID) form a network, conceptually equivalent to all of them being connected to a switch. But then all the devices on the access point can only communicate amongst themselves.

The router is needed if devices wish to communicate with something other than what is on the same access point.

Wifi itself fits in "layer 1" of the OSI model. It's job is to provide an infrastructure that can move Ethernet packets around and that's it.

Devices can communicate with just Ethernet packets but they would need to know everyone else's MAC address. 99% of them you will be using Ethernet packets to provide an infrastructure that can move IP packets around.

IP will still work without a router, you just have to manually assign IP addresses and make sure they are all in the same subnet, or tell your DHCP server to do that.

But if you want to talk to something in a different subnet, that's where a router is required.

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