Forum

Greetings All,

In this world of continued learning, once again I am trying to get caught up.

This may be on the wrong forum, if so let me know and I will repost correctly.

My question is as follows:

I am running a wireless network, and I have several clients that show that they are associated and authenticated with the AP. Their client utility shows 100% link quality and 100% signal strength. However, they are unable to ping or pass traffic.

Could someone explain the various layers involved and how they could be associated and authenticated but not be able to pass traffic? If you could start with the transmit of the beacon from the AP up the various layers of the connection, so that I can work with a packet analyzer to try and find out what is going on. This is an intermittent problem that is driving me crazy.

Thanks for your assistance in this discussion.

The clients may be Open authenticated and associated but not EAP authenticated and Associated which would also be required to contend for the media, if you are using EAP. What security is being used on the AP?

There could be a MAC filter in place that is blocking their packets from exiting the AP. The MAC filter would allow the clients to associate (and thus auth) but not allow packets to pass.

Joel

Keith.

While I don't have any enterprise level administration experience with WLAN's yet, I can share experience from a personal level...

Here at my humble abode, I have many different pc-card nics with my laptop. Depending on what kind of security I'm using on the AP (WPA-PSK, WEP or nothing at all), I too can get the same results some of your clients get. That is, fully connected (authenticated and associated) but no throughput. Sometimes this also happens and an IP is given successfully from a DHCP server. Other times it ends up with a 169.254.x.x address.

Ultimately, I've found different vendor equipment is my problem. Some nics work with WPA just fine, others only with WEP but not WPA, and others with no security at all. Maybe your particular clients are using a nic or different chipset that is not compatable with your AP network? Ultimately using a protocol analyzer on these problem clients will be a lot of fun! Please keep us all informed with your progress.

-Tim

Yes that is a strange anomoly:

What type of AP and client cards are in the setup? More than one AP?


Don't know if this applies... but check and make sure the AP is not in the network by itself in repeater mode. You need it to be the root AP . In repeater mode it is looking for the root ap to talk to to pass traffic on the ingress and egress.


http://www.cisco.com/warp/public/102/wlan-extend-radio-coverage.pdf


Otherwise it is one of the three Fs. Firewalls, Filters or Firmware.

Greetings,

In this particular case, I have been working with SMC products. Currently in place is an SMC 2555 in AP mode, with no WPA,WEP etc., and open system. I am also using the SMC2532 PCMCIA card in a notebook computer.

The notebook shows connected with 100% link quality and 90% signal strength. The SMC2555 shows client associated and authenticated.

But can't pass traffic.

If I reprogram the notebook for a different antenna site 3 miles further away, it will connect and pass traffic.

I have proven this in front of the SMC engineers that have been on site to try and help with this problem.

My question still remains:

Could someone step me through the process layer by layer so that when I bring up a packet analyzer, I will have some basis for my analysis.

Further, in the scenerio above the major difference is as follows:

The SMC2555 is putting out between 32-50mW into a 1W amp. The other antenna site the radio has 200mW out into a 500mW amp.

I have heard in some discussions that there is a relationship between xmit power and receive sensitivity, even though the specs on the equipment indicate that they are both around -83 to -87 dB at 11Mbps.

brownmil,

I understand your plight and fully understand your request.

My ability to explain this is not going to do you any good. I will leave that to the experts here that have more experience with this type of toolset.

In efforts to further troubleshoot this anomaly. Is this device using DHCP or are the address statically assigned? I had a similiar issue with a DHCP hang-up where the signal and strength parameters looked good but the DHCP was stuck and I couldn't pass traffic. The fix: ipconfig/release/ ---- iponfig/renew. Again this may not be the case.

You might not use this but here goes...

1. The link fade margin can be tested on that link by placing an attenuator (best to use a variable /step) on the link to verify the quality of this link is optimum and whether it is fading . Outside I would place it (attenuator) near the antenna between the antenna and the coax, see if the quality degrades.

2. On the good network utilize this toolset to verify the link throughput and return of traffic to the user.

http://www.ixiacom.com/products/performance_applications/pa_display.php?skey=pa_q_check

3. Run the packet analyzer on the good link and look at the outputs and save it to give you a comparison to the closer link.

4. Almost forgot :use Netstumbler to check the RSSI levels and SNR as well.

Look forward to the packet analyzers input as well. Hope this helps.