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Understanding the difference between a WAP and Bridge.


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#1 Mike19865586

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Posted 02 March 2010 - 06:33 PM

I am having the hardest time understanding the difference between a wireless access point and a wireless bridge. This information is crucial to me because I am planning on taking my Network + examination soon. I know the technical definition, but I cannot grasp how I would actually implement the two in a actual scenario. Could you guys please explain this to me without using too much technical jargon and it would also help if someone could provide some situations (perhaps drawings) in which a WAP or bridge would need to be used.

Thanks,
Mike

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#2 CaveDweller2

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Posted 02 March 2010 - 07:31 PM

An AP just adds a wireless signal. Something else is handling routing and IP addresses. All an AP does is add a wireless point of connection. Think of it like a hub, instead of plugging in wires you "tune" in to a wireless signal.

A wireless bridge is no different than a wired bridge in its basic job. It connects two segments of a LAN together, really the only difference between a wired and wireless bridge is how those segments talk to one another.

Lets say there is a company an older wired network. They have never had any reason to have a wireless signal. Now they want to add that capability but they don't want to buy all new equipment. They could just use an AP.

Now lets say that same company has grown, so they decide to move their accounting office across a busy street. They don't want to pay to have a wire run under that road. They could use a wireless bridge to connect those LAN segments together.

Does that help?

Hope this helps thumbup.gif

Associate in Applied Science - Network Systems Management - Trident Technical College


#3 Orecomm

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Posted 02 March 2010 - 10:46 PM

A Wireless Access Point is the Origination point of a wireless network. It connects to the main wired part of the network and "launches" the wireless radio signals. Those signals can be received by clients of various types. Most clients are single devices, and have a single IP address, and most importantly, a single MAC address. A Wireless Bridge is a special class of client that performs MAC address masquerading at the link level to allow multiple devices to share a single wireless connection.

Think about it, If I am a router sending a packet to a device on an attached network what MAC address do I use ? Mine as the source, and the destination system as the destination. Now insert an AP and wireless client into the link. The AP knows who the router is, and each destination has a unique MAC in a normal 802.11 network, so the AP knows who to send the packet to. But what happens when one wireless destination (MAC address) has multiple devices behind it ? Their MAC addresses are pretty meaningless to the AP, since they are not in it's association table. What does the AP use to reach them ? It needs to know the MAC of the wireless device serving them. Wireless Distribution Service (WDS) solves this problem by extending the wireless frame to hold up to FOUR MAC addresses - two for the "real" end points and two for the entry and exit points of the wireless network. Bridges predate WDS but had the same effect by masking the real MAC addresses over the air and substituting their own. In short, a standard wireless client device will only support one MAC address. A bridge or WDS node can support multiples.

Most older bridges came in pairs, actually an AP and client Bridge, because many of the bridge protocols need to pass information over the air between the units using proprietary protocol extensions. They were primarily point to point connections.

Hope this helps. If it's clear as mud post back and I'll try again. This particular topic is about 3 hours of the advanced wireless class I teach, so don't feel too bad if it doesn't make sense at first. Think like Layer 2 and it will come to you.

#4 MichaelH2

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Posted 10 December 2016 - 04:55 PM

Yes, it is clear as mud for me.  So in this scenario where the access point is connected to a switch that has several IP cameras hook into it as an example, Then, access point wont work because there are several mac addresses associated with the switch?  So that means I will need a (WDS) device or setup to make this work.  Am I correct?



#5 baines77

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Posted 12 December 2016 - 01:05 PM

Think about it in almost a literal sense - what does a bridge do?  It spans two points and brings them together.  In a networking sense, that is all a bridge does - it connects two networks together.  An access point is expanding the network to provide greater range/signal to a larger area instead of bringing them together like a bridge does.  Now, that seems like semantics, but there is a difference.  Some bridges will also provide wifi, but for simplicity sakes, we'll leave that out for now.  Here's a simple, but practical example I use in my own home:

 

I work from home in a 3 level townhouse.  My office is on the top floor with a workstation and a server, we'll call it LAN 1.  My modem is in the office with me, so is my Wireless router.  On the second level is our living room that also has a desktop, xbox, cable box/smart tv.  We'll call it LAN 2.  

 

So...how do you get internet downstairs to the smart tv/xbox/desktop when a) the desktop and tv do not have wifi capabilities, b.) since we rent, didn't want to get into running cable through walls/ceilings and installing a switch to throw lines from and c) don't want to pay for a second circuit from my ISP to get internet down there...how do we connect LAN 1 and LAN 2 together?

 

Solution - I have a bridge that picks up my wifi signal (coming from upstairs) and provides internet downstairs.  I then I plug all my toys into the bridge via Ethernet and I get basically the same up/down you'd expect on a wifi (12/60 in my case).  The bridge in and of itself does not provide a wifi signal, the router upstairs is still doing that, but it IS connecting the upstairs and downstairs together utilizing the one and only circuit I have coming into the house.  

 

If, say I wanted to get wider/stronger wifi coverage, I could then run a WAP off the bridge and expand my wifi coverage, though it's not needed as the router kicks a pretty good signal range and covers the middle floor, but I could put one down there to push wifi to the basement if I so chose.  

 

That help at all?


Edited by baines77, 12 December 2016 - 01:08 PM.


#6 MichaelH2

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Posted 12 December 2016 - 03:57 PM

YES, I think I got it now.  It is time to put it to the test to see if I really did, your example  is one of the other situation that I am in, the basement where it is tough to run wires to computers printer etc...  Thank you for your time, it is very thorough explanation.


Edited by MichaelH2, 12 December 2016 - 04:01 PM.





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