[WXC/VFX] Need wireless bridge?

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gchiu

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Topic # 13641 21-May-2007 18:01

I've got a user interested in getting a wrtp54g-au so that they can voip at their front reception. However their wireless AP ( Dlink) is at the back of their shop, and reception at the front is weak at best.

Would it work well for voip if they used some type of wireless bridge to connect the two wireless APs ?

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Reply # 71546 21-May-2007 19:20

It would be much cheaper to buy a phone extension cable and run that through the ceiling.

Low Tech but simple and foolproof

gchiu

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Reply # 71552 21-May-2007 20:09

My first suggestion to them was to run cat5e from the back to the front of their shop, but they also want to improve the wireless access so that they can stocktake with a wireless laptop.

grant_k

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Reply # 71578 21-May-2007 22:12

OK, in that case I would suggest running Cat5E cable as you say from the existing Wireless AP at the back to the front of the shop. Hopefully they have a spare Ethernet port, if not then buy a cheap 5-port switch.

Don't buy a WRTP54G-au but instead put a cheap Access Point with 4-port switch in at the front of the shop and set it to an IP address on the same subnet as the existing Dlink -- not the same IP address obviously

Then buy a Linksys PAP2T for VoIP and connect it to a spare port on the front Access Point.

Reasons I have suggested doing it this way are:

1) If you buy a WRTP54G-au, you will have 2 NAT devices in the one network which is sure to stuff up VFX.

2) The cost of a PAP2T ($100 approx) and Access Point ($50 approx) is much the same as a WRTP54G-au.

3) The second Access Point should immensely improve wireless coverage at the front of the shop and hopefully all points in between there and the back of the shop, depending on how large it is, internal metalwork/walls etc, etc.

P.S. If your ADSL connection can be relocated to the front of the shop, you could instead use a WRTP54G-au and forget the PAP2T, but then you would need to ditch the existing D-Link router, or possibly disable its routing functions and just use its Access Point and network switch (assuming it has one).

A few options to consider Graham...

Which do you think is best?

gchiu

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Reply # 71580 21-May-2007 22:21

I was hoping to put the Linksys WRTP54G-AU in the DMZ of the DLink WAP. Would that fix the double NAT difficulties?

Snikch

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Reply # 71844 23-May-2007 10:42

Tried a better aerial? if you get a larger aerial for the current AP (they are around $30) you may be able to boost you wireless range. Also try different positions of the current aerial, it makes a huge difference sometimes.

grant_k

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Reply # 71846 23-May-2007 10:52

gchiu: I was hoping to put the Linksys WRTP54G-AU in the DMZ of the DLink WAP. Would that fix the double NAT difficulties?

No, I don't believe it would...

Even though the DMZ forwards all incoming ports, you are still working through 2 lots of NAT which I believe will mess up the VFX service. It would be best to confirm this with Maverick, but that is my understanding. Hence the reason I recommended a separate ATA unless you can physically move the ADSL connection to another jackpoint at the front of the shop.

Snikch has also made a good suggestion re use of a better aerial, it's certainly worth a try but doesn't always help if there is interference, or metallic obstructions.

I hope that helps.

Cheers,
Grant.

richms

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Reply # 71970 23-May-2007 19:56

Wireless repeating is hit and miss, and some repeaters do arp proxying so anything on them is behind a single mac address. With no spanning tree this essentially means that you cant move that mac address between the repeater and the main ap and still have things work, plus there is the issues with the arp tables having to time out before connectivity will resume.

If you do decide to try it, and it doesn't work as you expect, its most likely nothing that you are doing, just the way things are. WDS which is the ideal way to bridge access points isn't clearly defined in the specs so each brand has their own way of doing it, And thats brand of chip inside, not access points. Then there is the massive hit in performance that you will take from the double handling of packets and the increased collision rate that will occur as a result.

Long cat-5, second AP, separate channels but same SSID and WPA keys is the way to do it but you will still not get totally seamless hand off between the 2 access points

Richard rich.ms

grant_k

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Reply # 71974 23-May-2007 20:04

richms: Long cat-5, second AP, separate channels

I had that bit figured out, but this part is interesting:

richms: but same SSID and WPA keys is the way to do it but you will still not get totally seamless hand off between the 2 access points

I take it that this allows the hand-off process to take place without manual intervention like clicking CONNECT or something like that?

How long would the hand-off process take (typically) in this case?

Cheers,
Grant.

richms

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Reply # 71976 23-May-2007 20:09

If I am playing music on the laptop and I take it into the garage, there is about 10 seconds of silence between it losing the house ap and associating with the garage one and starting to play again, theres nothing visable on the tray icon other then the signal dropping to nothing momentarily when going around the corner from the house. Some of that delay may be windows file sharing recovering from the packet loss, so something udp based may fare better. The IP is never released or renewed (to my knowledge) so it would have to be on the same segment.

As opposed to when I was trying to repeat it and it would get signal and then have no thruput for about 5 mins because of all the mac address carryon.

Richard rich.ms

Snikch

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Reply # 71978 23-May-2007 20:10

Oh yea I forgot! I tried using wireless repeating once, and I only managed to get around 200kbps throughput, nowhere near what I wanted. I could connect to the network from the same place with a laptop, and would get 10mbps! Something cause it to go unbelievably slow, was not a good experience.

richms

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Reply # 71985 23-May-2007 20:24

The repeater has to get the frame from the client in its entirety, then transmit it to the accesspoint, chances are that the accesspoint has something to send at the same time so there is a collision meaning that the client ends up retransmitting it to the repeater, etc etc etc

If you lower the RTS values you can increase the repeated performance, at the expense of the non-repeated performance. Also, if the repeater is only getting poor signal from the access point, that will further slow it.

Richard rich.ms

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Reply # 71990 23-May-2007 20:33

I have no experience with this, but the theory with duplicate SSIDs would be that the first connection drops out, Windows retries for a short timeout (which I suppose you would be able to set to a shorter duration in a registry key), then when Windows decides to reconnect rather than recover the failed connection it immediately finds the nearby one and connects. Most of the 10s delay would be trying to recover the failed connection rather than establishing the new connection. If your data is not time critical, then the handover would simply be a short delay in data transfer (it will be buffered) similar to a brief delay on opening a web page. Again, this is more theory than experience but might be useful for someone to give you practical advice.

You can never have enough Volvos!

gchiu

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Reply # 71991 23-May-2007 20:34

Ok, I'll see if I can persuade them to drop a wire to the second AP. If they go for this, I'll set up non-overlapping channels such as 1 and 7.

Maverick hasn't chimed in whether they should just get an AP and PAPT, or whether it's feasible to use the WRTP54G-AU ...

grant_k

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Reply # 71994 23-May-2007 20:41

gchiu: Maverick hasn't chimed in whether they should just get an AP and PAPT, or whether it's feasible to use the WRTP54G-AU ...

Send him a PM Graham and you'll have an answer in the wee small hours of tomorrow morning for sure. He is a seriously early riser and will probably be catching Zeds by now...

gchiu

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Reply # 72023 24-May-2007 08:11

Maverick replied that it should work if it is setup correctly. A minor caveat

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