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I need to set up wireless access for my company headquarters. We live in a 4 story building and all 4 floors need to be covered. Currently I have 4 WIFI routers (Checkpoint SBOX, combined FW+router), each located at the middle of the respective floor, providing somewhat adequate coverage.

Problem is, every floor has it's own wireless network (wnet1-wnet4 respectively), and even though the password is the same for all of them, the user still needs to disconnect and connect again to the required network if he moves between floors.

Is there any way I can set up some sort of roaming, so that the entire building is covered by a single network? Preferably, without buying additional equipment too.

Thanks!

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5 Answers 5

up vote 8 down vote accepted

Just set each router to use the same SSID but a different channel. Users will see it as a single wireless network when they move between floors. The different channels will ensure that the routers do not conflict with each other.

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5  
All the APs need to be in the same broadcast domain and they must not all be acting as routers. –  chris Jun 30 '09 at 14:56

Some access points provide Wireless Domain Service, it makes then possible for the access points to cache and share the credentials of associated clients thus reducing the required time for the clients to re-associate when changing from one access point to one other.

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The wireless access points must be in bridge mode and dumping the wireless traffic into the same vlan (layer 2 broadcast domain).

They must have the same ssid. They should be on different channels. With 802.11b/g, even though there are a bunch of channels, you should stick to channels 1, 6, and 11 and not have adjacent APs have the same channels. http://en.wikipedia.org/wiki/IEEE_802.11#Channels_and_international_compatibility

If you leave the APs in router mode, each AP will be creating an isolated wireless network with it's own address space and when a client roams from one to another their arp tables and IP addresses may not be reasonable for the new network.

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Thanks, i didn't think about the bridging, it would probably be better overall. We actually ended up setting each AP as a router with non-intersecting ranges of DHCP addresses they provide. It's enough for what we need. I suppose i'll set them up to be bridged and broadcast the same network just for the fun of it if i ever have a spare hour or two to tinker with it. –  V. Romanov Mar 4 '10 at 12:37

What you're talking about is a wireless routing mesh, which provides wireless coverage wherever you go for the same "wireless network". Depending on the capability of the device, this may or may not be possible - some of the cheaper routers will not accomodate the necessary changes needed to support a mesh.

I do know that there is purpose-built hardware for this. For instance, my work has a set of Motorola WS5100 units that provide coverage with 12 access points scattered throughout the building, but it requires specialized hardware.

If you are planning on doing this with commodity hardware, you will want something that supports:

  • both ad-hoc and infrastructure mode (ad-hoc supports point-to-point mesh routing);
  • you'll want to set all stations to the same SSID;
  • use the same shared key;
  • force the APs to function as strict routers, and not provide any other network services (can you imagine the chaos of having 10+ points providing their own DHCP grants?);
  • you'll probably want something that has adjustable power output, to help reduce overlap;
  • and probably, you'll want a 2nd authentication factor, such as RADIUS or certificates or something else, "just in case".

Of course, it wouldn't hurt to have some or all of those access points tied back to a switch somehow, but if you're doing a wireless mesh, this won't always be necessary - the mesh will "forward" the packets from stand-alone units as needed. And there lies the rub - getting the mesh to forward to the correct location.

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It sounds like you are covering alot of ground, but DDWRT may be able to do this. I know it can act as a repeater, but I dont know to what extent.

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