Adding Wireless to Cable Connection

[Aharon Schkolnik]

On Monday 12 October 2009, shimi wrote:
> On Sun, Oct 11, 2009 at 8:43 AM, Aharon Schkolnik 
<aschkolnik at gmail.com>wrote:
> > On Thursday 08 October 2009, shimi wrote:
> > > The right way to do it is not with an Access Point. Someone needs to
> > > "multiplex" your connection to multiple devices. Since you have just
> > > one external IP address, someone needs to "share" it between your
> > > multiple machines and do "magic" that makes it (multiple unicast
> > > machines between one unicast address) work. We call that magic-maker
> > > a "NAT router" (which basically every home router does).
> >
> > Yeah, I realize that I need NAT (or PAT in Cisco terms), but I thought
> > (I admit I didn't check) that the AP might do the NAT.
> 
> A pure AP is a "wireless switch" - it talks Layer 2 only.

Yeah, but a lot of consumer oriented products are not pure anything. Guess 
that's why I thought the manufacturers might have decided to toss NAT in 
where it really doesn't belong. On the other hand, I didn't give it much 
thought, and if I had, I would have realized that that was an unlikey 
scenario given the leap in complexity needed to add NAT to a simple AP.

> 
> > > So what you
> > > need is an Ethernet router (with an Ethernet port on his WAN port).
> >
> > Thing is, I was wondering why I need a router. I don't need it to do
> > any routing decisions (unless I want to share files between connected
> > PCs, which I don't). I do need NAT, but I kind of thought an AP would
> > do that.
> 
> NAT is performed at Layer 3 (some would even say Layer 4?). A layer 2
>  device does not understand (nor cares about) these layers at all. It
>  can just forward frames...

I'm pretty sure it's considered a layer three function. Anyway, certainly 
not layer two.


> 
>  -- Shimi
> 


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