Posted by: §intå×

Wi-Fi - 12/19/02 10:28 PM

Dose any one know of the various protocols involved in Wi-Fi(wireless networking) and (pushing my luck here) a link to sites with info on these protocols. I already know about IEEE 802.11

But I am looking for something like a suit of protocols and a break down of the actual datagrams, or packets. In other words

|Header info 5 bytes|CRC check sequece 1 byte|payload 53 bytes|

Above is something like what I am looking for here. I wana study the actual bits and learn the actual packet layout per protocol. Any ideas?
Posted by: Infinite

Re: Wi-Fi - 12/19/02 11:38 PM

Wi-Fi IS 802.11a and 802.11b. Those two subgroups describe the physical and data link protocols used in Wi-Fi. So by definition if you look at those standards you are looking at those 2 layers and how Wi-Fi uses them. As soon as you hit the network layer you are out of the scope of Wi-Fi.

So having said that, the standards are available in pdf form from the IEEE themselves, and I beleive those contain the info you are looking for. Go here:





There's the 802.11a, 802.11b, 802.11b supplement, and 802.11d specs. Everything you ever wanted to know about Wi-Fi, and a whole lot you really don't care about. Happy reading.

Posted by: §intå×

Re: Wi-Fi - 12/20/02 12:30 AM

Nah, See 1's and 0's are set in Layer 1 or on the physical layer, They start being grouped and diveded into packets in Layer 2 or the Logical Layer. I am looking for info on the packet headers and footers.

What it is that gets it from this peice of equipment to the next. In other words from one signal station to the next. I am looking to info on the actula bits not bytes. what each bit in the header dose. Layer 3 would be Layer 2's payload.

See I wana learn about the over head. This is where you will be able to snag packets and send them back out so no one notices.
Posted by: Infinite

Re: Wi-Fi - 12/20/02 12:51 AM

/me nods as Learner says a whole bunch of things he knows.

I think we're having what's called a communication breakdown here. Or I really am just not understanding what you are asking.

Nah, See 1's and 0's are set in Layer 1 or on the physical layer, They start being grouped and diveded into packets in Layer 2 or the Logical Layer. I am looking for info on the packet headers and footers.
Right. Layer 2 is actually divided into frames, but why be anal about it =, and layer 2 is the data-link layer, not the logical layer (in OSI at any rate). Now layer 2 is divided into the MAC (media access control) and LLC (logical link control) sublayers, each handling part of the data-link layer's scope.

So, when talking about "Wi-Fi" what we are talking about is the pysical means of transferring data, and the way to access these physical media.

AS far as the protocols, Wi-Fi uses TCP/IP in most applications, meaning that all the layer 3 protocol used is IP. So what I'm saying is once you get to the IP portion of the packet it has the exact same structure as a wire packet does (as far as TCP/IP is concerned).

That leaves us Layer 2 for protocols and packet structure. Which is fully explained in the documents I referred you to. What bits correspond to what portion of the headers and footers, and what the field's names and purposes are.

And remember with Wi-Fi, info is not transmittied the same way as on a wire. The encoding scheme to RF signals is a lot more complex than say manchester encoding used on wire.

I dunno, everything you're asking for is in the links I gave you man. Those are literally everything there is to know about wifi. I know the 802.11a doc has a complete, bit for bit, example of a typical packet sent using 802.11a. It is 6 pages of each individual bit explained. If that's not what you mean then I'm totally lost.

Posted by: §intå×

Re: Wi-Fi - 12/20/02 12:57 AM

/me hang head in shame.

I miss understood you completly and didn't read to far into the links. That will do, As far a the OSI modle gose it is still the logical layer. It dose what the rules in the OSI modle stat it should when it climds that high. Call it what you want, but that is what is happening.

I knew once you got to 3 or 4 it would use the protocol suit you are using. ie TCP/IP, SMDS, Frame Relay, ATM, Appletalk, Vo/IP, etc etc I just wanted all info up to that point and it looks like I am an ass for not seeing what you gave me. Thanks.
Posted by: Infinite

Re: Wi-Fi - 12/20/02 01:04 AM


Cool, I was getting really confused there for a min.

And not to argue, but the logical layer? I have never heard that term used for Layer 2 of the OSI. Most of my experience with OSI related material comes out of the Cisco Academy traing for the CCNA, and in there it is referred to as the "Data-link" layer of the OSI 7 layer model. I'm not surprised to learn another name for it, there have been a few things in that package that are named or explained the way Cisco thinks it should be, and not how it really is. *Shrugs*

Posted by: §intå×

Re: Wi-Fi - 12/20/02 01:23 AM

Data link Layer....


Looks like many a site agree with them. I was taught it on the job at verizon and deal with nothing but networking. It could very well be they were wrong. However that SUCKS! I have thought it was Logical layer all this time and now I am wrong 2 times in a post!!!

BTW a cool OSI tut