D-Link access points keep crashing

[HodgeHi]

Hello all,

 

I am currently setting up wireless access across the entire school so staff can use the connections from their rooms. I have however run into many problems. The APs all sem to be set up correctly.

 

But instead of going through what I've done again i will post the link to a previous forum i used earlier.

 

wifi planet

 

Any help would be great.

[Geoff]

But instead of going through what I've done again i will post the link to a previous forum i used earlier.

 

Some people wont be able to read it because of their schools web filtering. Also it helps when searching for stuff later if all the information is in the post.

 

Anyway:

 

Hello all,

 

I am currently installing a wireless network in a school using PoE and dlink access points. These are DWL-2100+ (APs) and DWL-P100 (PoEs). There are around 18 APs at the moment.

 

The layout is like this...

 

There are two buildings, East and West.

East is L-Shaped with the longest part having three floors.

West is three floors high for a majority of its coverage.

 

The problem i am having is with the coverage for these buildngs. East sems to be stable at the moment but i won't hold my breath...West on the other hand is a nightmare.

 

The APs seem fine but for unknown reasons just fail and cease to respond to anything even the web interface.Its not just the odd one however. There are around 6-7. A Dlink consultant came in to do a site survey and suggested around 11 to cover both buildings and also said that the PoEs would be fine for these APs. There are also no new firmwares for my APs from what i can gather from their website.

 

At the moment i am running basic WEP (will be upping security once it is up and running properly). All APs are set to same SSID and each floor has usually two to three APs as the corridors are long.

 

There can be up to around 11 members of Staff using the one AP at any one time maybe more..it depends on who connects to what AP. The channels are all set as far apart as possible to avoid confrontation. I have also tried to pull back the signal broadcast strength as to avoid further interference but they still overlap from floor to floor i.e. according to WZC top floor APs can still be seen.

 

All i need help on is to figure out why the APs keep failing as this creates large gaps in the wireless network because as i said before the corridors are long.

 

Do the AP's keep a log? If they do, you might want to have a look and see if there are any errors. You could also try disabling settings and see if that helps. I've had AP's have broken encryption support that took them out after awhile. Another thing that occurs is that they might be overheating? Are they sited somewhere with decent ventilation?

[Dos_Box]

I've had so many dissapointments with D-Link APs' I've vowed never to use them again.

Ever.

[HodgeHi]

Hello Geoff,

 

I have outlined the problems below.

 

The problem that we are having is the following. The access points have been implemented and are powering through POE and the locations are around two per corridor in the West Building and 2 on the first corridor providing coverage for the lower floors and to some extent the upper floors. They are situated above the suspended ceiling.

 

The issues we are seeing are the access points suddenly become unavailable to the clients. The WAPs are configured to different SSIDs to differentiate which WAPs can be seen on each floor. The WAPs are also set to different channels. They are not necessarily the three that are better used for the WAPs as we have a different collaborated school that have implemented their own WAPs and have used CH7. To avoid any interference I have used alternative channels. The Encryption at the moment is set to WEP but only until I can stop the WAPs crashing.

 

The logs have also been set up but once the WAP is power-cycled the logs are lost. Syslog is set up but doesn’t really tell me much about whats going on.

 

I have also tried to configure SNMP but have yet been of any use until configured properly (which I am unsure of how to do).

 

I have used NetStumbler to determine any noise that can be seen but it registers as having no noise. I have pulled back the signal strength to avoid any issues with interference from other WAPs in the surrounding area.

 

The WAPs do not respond to pinging or client connection attempts or even connection to the Web manager, and need to be power-cycled to get back online.

 

 

This more or less covers whats been going on.

 

 

I never thought about the overheating issue. I will check this out.

[Guest]

Not the best APs in D-links range. I have a few of those still knocking around and yes they too just fall off the network. Restart them and they come back online again... for a while.

 

On the other hand the DWL-3200APs with inbuilt PoE are in my experience rock solid, but then they do cost 3 times as much.

[Geoff]

A couple of things stick out.

 

1. You really should use the same SSID everywhere. I know setting ones based on location help when your sorting things out but it breaks roaming and confuses Windows XP ZWC.

 

2. You should set the AP's to different channels. Nearby channels interfere with each other. You should set AP's to either channel 1, 6 or 11 and keep AP's with the same channel numbers as far away from each other as possible. Some planning will be required to workout the best scheme.

 

3. Your basic problem does sound like either a firmware bug or overheating. I suspect its the first. I suggest you bother dlink about it. If that comes to nothing I suggest you get your money back. We can make some recommendations as to alternative systems to buy.

[HodgeHi]

It's great to hear someone else say that they are a bit flakey. I thought i was doing something wrong.

 

I also forgot to mention that i have also upgraded the firmware to the latest version. 2.12 and have set the IPs to Static and out of the DHCP scope range. So there are no ip conflicts.

 

 

The cards i use top connect to them are also D-link G650+ with which i disabled the Util as it kept starting and stopping, and sometimes not even finding its own card installed. Couldn't see any firmware updates for these.

 

I also use some Sweex cards (by the way both types are 11g) and these seem to be solid. Don't recall any problems with these aprt from two not working at all.

 

and finally PDAs and some Acer laptops both using 11b.

Thats more or less all the wireless stuff we use.

[alexknight]

Same here, DLINK AP's just dissapear until you reset them. Very Odd.

[HodgeHi]

Hello all,

 

Thanks for the replies.

 

Its good to know other people have had the same problems. No one has been able to pin point the problem though?

 

We have 18 in total implemented so it is going to be a problem replacing them all (cost-wise) and theres more of them in the cupboard but these arent opened yet.

[Geoff]

I think we have pinpointed the problem. DLink suck.

[HodgeHi]

Problem solved then.

 

I was just hoping for a resolution that wouldn't leave me with 18 bricks with poles sticking out of them.

 

I have a D-Link consultant coming back in (he came out to do the site survey) and he will be trying to find a solution, I hope.

 

I will post what he says. He's not in until June though...

[Geoff]

I hope he does. It's just a shame you hadn't posted before you purchased the equipment. You might of avoided all this hassle.

[HodgeHi]

Indeed!!

 

Although the survey was only done last October (i've been trying to get my head around it for this long until i decided it can't be anything i'm doing wrong surely?) the equipment recommended to us was the DWL-2000+, which to me is odd after browsing their site, its not even in the list under the educational section and is now discontinued...

 

We can only wait and see.

 

Thanks for your inputs anyway.

[ChrisH]

I hear plenty of bad stories about these 2100 APs but.... I have about 8 of them dotted around running of a POE adaptor and I have never had any problems. I must have just got lucky for once.

The only thing I will say about them though is to update the firmware immediately as the firmware that ships with them is very bad.

[Ric_]

I had one of the 7 D-Link 2100 APs at my last job which regularly locked up for no reason.

 

The D-Link gear sucks.

[eean]

We have 8 d-link DWL-2100 aps now with the POE. They run Ok but I've switched Off any fancy settings like xtreem G (but have turbo on). We would reguarly have 15+ computers conneting to one point.

 

Have you tried:

--them in WPA-PSK? Mine seem to run reliably in that mode since a firmware update last year. Or even no encryption (for testing)

--removing certain brands of client (esp those b devices - then you can have it on G only - any b devices connecting slows down the whole access point). We found Dlink wireless -> ethernet adaptor (G810) we bought for a printer crashed every AP nearby.

-- Auto channel scan - the AP selects the least busy channel and it actually seems to work. (Newer Netgear APs will autonegotiate and turn down other netgear APs, apparently).

 

OUr main problem were the d-link cards. They caused our RM (compal) laptops to run at 100% cpu. D-Link support were useless. (RM were surprisingly helpful - but still useless!). In the end I found a driver on tsd.dlink.com.tw fixed it but dlink europe denied it even existed.

 

We still have a problem where the notebooks freeze for about 1 minute after 20 minutes' use. They recover and are fine - but not after a few 6 year olds have poked them. Doesn't happen on our desktops. Odd.

 

So yes, D-Link are rubbish.

[Pear]

We have 13 of them. I find that some of them crash every few weeks, however the one in my room crashes all the time. I discovered that this is because of the centrino technology in the laptop, it doesn't crash when I use linux, it doesn't crash when the charger is plugged in. But if its running Windows and not charging it crashes after about 5 mins.

 

I tried putting another wireless card in my laptop and had no problems with it, but since I use the linux now it wasn't so much of a problem until we got some new laptops last week, centrino ones. The access point in the staff room keeps going off so I'm going to have to tell the owners not to use them without chargers

[OverWorked]

I've had D-Link APs for over a year now, and had all the same problems: The access points work fine for a while and then just disconnect. It's impossible to ping them from either the wired or wireless side. The only solution is to reset them.

 

In our case, and I suspect yours too, the problem doesn't lie with the access point (not entirely anyway). It's spanning tree protocol (STP) on the switches that they're connected to. After a while a stray packet will move wirelessly from one AP to another. The switch will see this as a loop in the network and stop all traffic to the offending APs.

 

After Elus1v pointed this out to me, I noticed that it only affected APs connected to the fancy 3com switches. APs conected to the cheap switches that didn't have STP were unaffected.

 

I've disabled STP on the switch's ports the APs are connected to, and now the problem is reduced. AP's now only ned resetting once every couple of weeks, not every couple of hours.

 

There are some more expensive AP's (£200) that are supposed to eliminate this problem. I don't know the details, but they're designed to be used as part of a network. The D-Link ones are only intended to be used alone (eg at home).

 

Does this help? You've described the same symptoms as I had, and STP was the answer for me. I'm now looking at phasing in the better APs.

[eean]

Oh and... all of mine are on POE which are plugged into a multibar at the server end. So I have a timer switch on that multibar to switch them off at night.

This was initially because we had some dodgy wiring which caused one of them to blow up, melting the whole POE adaptor!

However, it has the added advantage that it reduces the risk of hacking and it gives all the adaptors a good clean restart every night.

[secman]

This is what makes this site so useful. We are just starting to look at putting in Wireless networking across our site and are intending to look at DLink as it is a recommended LEA Supplier.

 

As so many have suggested that the kit is kess than stable, what other equipment are people using?

 

Might be a good idea to start an Edu-Geek approved list of hardware just like the essential software list.

 

Thanks

[Norphy]

We tried DWL-2100APs once. We ordered six. None of them worked out of the box, I turned them on, connected them to a PC to configure them and the AP kept on dropping its connection to the computer. It didn't even stay up long enough to attempt a firmware update. Contacted D-Link, got them swapped. Replacements did the same. Eventually got my money back on them after a lot of arguing.

 

Using Linksys for the most part, they work OK-ish but have similar random locking problems.

[Geoff]

I use Buffalo kit here.

[HodgeHi]

I've had D-Link APs for over a year now, and had all the same problems: The access points work fine for a while and then just disconnect. It's impossible to ping them from either the wired or wireless side. The only solution is to reset them.

 

In our case, and I suspect yours too, the problem doesn't lie with the access point (not entirely anyway). It's spanning tree protocol (STP) on the switches that they're connected to. After a while a stray packet will move wirelessly from one AP to another. The switch will see this as a loop in the network and stop all traffic to the offending APs.

 

After Elus1v pointed this out to me, I noticed that it only affected APs connected to the fancy 3com switches. APs conected to the cheap switches that didn't have STP were unaffected.

 

I've disabled STP on the switch's ports the APs are connected to, and now the problem is reduced. AP's now only ned resetting once every couple of weeks, not every couple of hours.

 

There are some more expensive AP's (£200) that are supposed to eliminate this problem. I don't know the details, but they're designed to be used as part of a network. The D-Link ones are only intended to be used alone (eg at home).

 

Does this help? You've described the same symptoms as I had, and STP was the answer for me. I'm now looking at phasing in the better APs.

 

The problem is that all the Aps that are on the same switch are not failing. I have one on one switch on it s own failing and one failing on a switch shared with around three others that do not.

 

I also have one that has been solid since implementation on a switch that is also shared by one that has never been working properly. (both of these aren't in the same vicinity.

 

 

I have also removed WEP encryption entirely and monitored the WAPs. The two that are the biggest issue didn't even last 24 hours.

[HodgeHi]

Hello all.

 

I said i would update the topic with the response i got from the D-Link consultant when he visited us so here goes.

 

He did not even look at any of the APs around the school (just as well as they are in the suspended ceiling) but checked the settings on one in the ICT office.

 

He said the wireless side of things seems fine and that he reckons its the ethernet side of things that are not working correctly. He is going to send some new WAPs (DWL-2100's) to see if these resolve the problem. We are now waiting for these to arrive.

[ChrisH]

Hello all.

 

I said i would update the topic with the response i got from the D-Link consultant when he visited us so here goes.

 

He did not even look at any of the APs around the school (just as well as they are in the suspended ceiling) but checked the settings on one in the ICT office.

 

He said the wireless side of things seems fine and that he reckons its the ethernet side of things that are not working correctly. He is going to send some new WAPs (DWL-2100's) to see if these resolve the problem. We are now waiting for these to arrive.

 

You will probably still ahve trouble. Make sure you update the firmware to the latest version straight away if they need it.