Point to Point Links

I need to link two small LANs with a point to point wireless link.

The two small LANS are just groups of PCs connected to a 10/100mbs switch with patch cables. One of these small LANs has a broadband connection that the other LAN wants access to.

If I use two Wireless access points in point to point mode does the combined LAN now become one TCP\IP network, i.e. will all devices be within a single 192.168.0.xxx network ?

Can the wireless access points, when in point to point mode act as a normal access point as well ? i.e. if at either end I want to connect a wireless equipped laptop do I need an additional wireless access point at that end ?

If I want to use DHCP do I set this up on one of the wireless bridges, or both - each with a seperate TCP\IP address range ?


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Thanks for the reply

The distance between the LANs, where the access points could be located is about 20M, in a simple test with a normal access point and a notebook it worked fine.

I see, so its possible for one of the pairs in the 'bridge' to act as a normal access point but not the other.

A fair point, if the bridge is setup to be one TCP\IP network then the PCs on the LAN without the broadband router ought to be able to access the DHCP server on the other side of the bridge.

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It is my understanding (which is not a whole lot) that AP Client mode wont handle multiple macs by itself.....Correct me on this if its BS. A workgroup bridge is also an option for the remote end and an AP at the host side.

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Ed Williams

snipped-for-privacy@yahoo.co.uk wrote in news: snipped-for-privacy@g14g2000cwa.googlegroups.com:

What is the distance between the two LANs?

  1. If they are some distance apart (say > 30m) you will likely need a mating pair of multi-mode access point devices, configured in wireless bridge mode. [The advantage of this configuration is that with line of sight, some height, and directional antennae you will be able to bridge several miles]
  2. If the distance is < 30m, you may be able to use two multi-mode access point devices, one configured in access point mode, the other in wireless client mode.

Think of the wireless bridge as a long length of Ethernet cable. So assuming you have a single DHCP server, you will create a single network and each DHCP client will be handed an address in the same subnet.

You can of course be more complex and bridge between two routers. You can then have different network address on each LAN. It depends on your requirements.

If you are using a mating pair of bridges (Option 1. above) then the devices will not also act as access points [but see below]

If you go for Option 2. above, then you will already have an access point and the laptop will be able to connect. Again, it depends on the distance, and also on the environment. It is possible that you may need additional access point(s) to fill in 'dead spots'.

A number of devices implement WDS (Wireless Distribution System). Although WDS is described in IEEE 802.11 it is not fully defined, and implementations betwen different manufacturers (and even between different products from the same manufacturer!) are likely to be incompatible. Some WDS devices can act as both wireless client and access point. I do not have personal experience of a device in bridge mode also acting as an access point, but some may do so.

[See also above] If you have dfferent network addresses on each side of the bridge, you will need to route between them. In that case, it is likely the router(s) will be the DHCP server. The simplest configuration is however a single network with a single DHCP server.

In my experience, this class of device will only act as a DHCP server when configured in access point mode, so if you go for the 'mating pair of bridge' approach (Option 1 above) you will need a separate DHCP server. If you go for Option 2. you will already have a device which can act as the DHCP server.

You say "One of these small LANs has a broadband connection". Assuming this is a broadband router, then this should act as the DHCP server rather than the access point.

The configuration you talk about is exactly how my network is configured. It is structured as small workgroup clusters of 2-3 PCs + print server, connected to a switch. Also connected to each switch is a wireless client device. A wireless router provides infrastructure mode wireless comms, together with Internet access to all users. Laptops can roam freely, although I do have futher access points (same SSID) in addition to the wireless router ['Workgroup' in this context means 'group of workers' rather than Windows network workgroup, of which there is only one]. Works just fine.

Hope this helps

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Richard Perkin

snipped-for-privacy@yahoo.co.uk wrote in news: snipped-for-privacy@c13g2000cwb.googlegroups.com:

A couple of points:

- If you don't have one already and you're looking to save money, you could buy a wireless router and offset the cost by selling the device you have already (presumaby without wireless). The new wireless router would of course be an access point. However, this type of single-box device does offer less flexibility in terms of positioning.

- the device I have called a multi-mode access point is, as far as I'm concerned, a 'normal' access point. Most (all?) models from most manufacturers support several modes, usually: access point wireless bridge multi-point bridge wireless client repeater

Provided it's configured as an access point :) [avoiding for the moment any discussion of WDS] You can have as many access points as you like (avoid overlapping channels).

Precisely. Don't make things too complicated :)

Hope this helps

Reply to
Richard Perkin

As others have pointed out, two AP's that are cable of "Bridge Mode" will bring these two LANs together. Each AP in "Bridge Mode" is half a bridge. You can either keep two IP networks or merge them together as one. Whichever you prefer. When I think of a bridge, I think of something that is connecting two seperate IP networks though.

The (WDS capable) DWL-7100APs (802.11a, 802.11g) that I just picked up are 'supposibily' capable of doing such -- operate simultaneously as both a half bridge and an AP for each band. As I don't need bridge functionality, I haven't tried it though. Due to firmware problems with these APs, it became a major headache just to get it operating in "Repeater Mode" for both bands. (Latest firmware couldn't do it, but after rolling back to a previous version, I got it working.) During the course of trying to get it working, I did a lot of google/deja searches -- which led to many others having similiar problems across many manufacturers (Linksys, D-Link, Netgear, etc). Seems like many manufacturers still have a ways to go with "WDS". Also came across many postings stating that specific APs were handling "WDS" beautifully. *shrug*. I'd probably do a lot of homework if looking for such APs. Read the reviews, see what others are saying about them, ect. As for the DWL-7100AP, unfortunetly right now I couldn't recommend this AP for anything other than use as an AP. Hoping D-Link releases a new firmware that takes care of it's issues soon.

Cheers 'n beers!

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"Airhead" wrote in news:420caf37$0$22516$ snipped-for-privacy@news.cablerocket.com:

The ability to handle multiple MAC addresses is one of the things which is never well documented. Most (but not all) devices sold as 'gaming bridges' will do it.

Most multi-mode access points which implement repeater mode will do it. This is because repeating is an implementation of WDS, so it's likely that WDS is also used to implement wireless client mode.

MAC frames as defined in IEEE 802.11 uses 4 MAC addresses. These are: DA: Destination Address - the final destination SA: Source Address - the originator RA: Receiver Address - the immediate recipient TA: Transmitter Address - the immediate transmitter

Using all four addresses together with the To DS and From DS fields within the Frame Control field is what allows a WDS implementation to handle data to/from multiple MAC addresses. If the wireless client device is programmed to structure its MAC frames correctly using all four addresses, it will work. If not, it won't.

This can be observed if the traffic is sniffed using Ethereal or other similar tool. Both the addresses of the wireless client bridge device and the actual device behind the switch will be seen.

I belive that such consumer-class devices can usually handle a total of 32 MAC addresses.

Reply to
Richard Perkin

Correct me if im wrong but this is what you have now correct?

InternetBridged AP1 (@20M) Bridged AP2

Reply to
Robert Jacobs

Thanks for the comment about homework, from what you are saying it seems that soem of the features that are advertised dont work to well.

Can anyone suggest a decent referance site for background info on the various wireless modes and how they are supposed to work ?

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Yes that is the way I want it to work.

As it happens they are all static configured for IP at the moment.

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Netgear, etc).

Have you seen any pattern as to which access point seems to be recommended by most people. I am looking for an access point that can operate in 802.11a/b/g modes; but I will probably need to use more than one access point. And in that case, bridging is likely going to be the configuration that I need.

These requirements seem to somewhat limit the number of choices that I have.


Your last statement seems to contradict what you were saying earlier. You made it sound as if rolling back the firmware to v1.00 fixed all your problems. Is there something that I am missing?



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