Can AP operate in layer 3 OSI model?

jakkijakki Registered Users Posts: 4 ■□□□□□□□□□
I just wonder if AP nowadays can be operated like a router in some sort, does it count to work in the network layer then? I ask this because the books I am reading say it only work on layer 2 in the OSI model. Thx in advance! icon_study.gif


  • Snow.brosSnow.bros Member Posts: 832 ■■■■□□□□□□
    I am no expert but i have been studying Net+ for quiet some time and based on what i have been studying an access point is a layer 2 (data link) device of the OSI reference model. In the layer 3 hardware of the reference model we have a routers and i think VPN concentrate-rs and firewalls as well.

    Anyone who is does not agree with my comment feel free to criticize my comment.
  • ptilsenptilsen Member Posts: 2,835 ■■■■■■■■■■
    The AP portion of the device would be layer 2, but if it is a router then it is generally referred to as a layer 3 device. A layer 3 device will still have layer 1 and 2 functionality/reliance, but we don't refer to these as layer 1 or 2 devices. Similarly, we wouldn't call them APs or switches, even if those are built in. A router with a wireless access point built in is called a wireless router.

    Snow.bros, a firewall is minimally layer 4, traditionally, as even a basic firewall performs specific transport-layer functions and is transport-layer aware. However, this is where both colloquial usage and the OSI layer get a bit murky. I could make an argument that anything that performs any type of NAT is a layer 4 firewall, but you will rarely hear a NAT-capable router referred to as a firewall, or at least it seems that way. Firewalls can go up to layer 7, in any event, and VPN concentrators would generally be considered layer 5.

    As a final note, I wouldn't get too hung up on these definitions. The OSI layer is an abstraction. It's a useful abstraction for troubleshooting, but still an abstraction, and a flawed one at that. Actual network protocols are not designed to fit into the definitions of the OSI layer, and some protocols and devices can defy OSI layering. There's even an entire RFC devoted to the problems with using abstract layering models. Again, for troubleshooting networks and passing certification exams, you'll want to know the OSI. Just don't get too hung up on the nitty gritty.
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  • jakkijakki Registered Users Posts: 4 ■□□□□□□□□□
    thanks for the reply! i think i got it now! icon_cheers.gif
  • DarrilDarril Member Posts: 1,588
    Great points ptilsen. The OSI model is just a model and in practice many of the labels become murky.

    From the Network+ perspective, it's valuable to know that 802.11 (wireless technologies) operate on both layer 1 and 2 and a basic access point (AP) operates similar to a basic switch (layer 2 switch).

    A "wireless router" is an "access point with a router" or a "router with an access point" depending on your perspective. As ptilsen points out, the AP is still an AP and the AP still operates on layer 2. The routing component of the wireless router operates on layer 3.

    One way that many people get confused is by clumping both wireless access points (WAPs or sometimes just APs) together with wireless routers. They aren't the same thing. All APs do not have routing capabilities. However, all wireless routers do have AP capabilities.
  • MrXpertMrXpert Member Posts: 586 ■■■□□□□□□□
    Wireless APs work at the data link layer. Radio waves operate at physical layer. If however you have a Wireless Residential gateway which is basically a Wireless access point with routing functionality then it covers layers 3,2 and 1. A lot of people generalize the terms quite a bit. For example the word "AP" is bandied about quite a lot and some people believe it is the same as a wireless router. Not really the case. it is a bit like words which have become synonymous with the product. For example Walk-Man,Kleenex (i;ve heard Americans call tissues this)
    I'm an Xpert at nothing apart from remembering useless information that nobody else cares about.
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