Connectivity Issue

Unanswered Question
Sep 24th, 2010
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Hi,

Im new to troublshooting Wireless issues etc and this is a strange issue, Im not overly sure where to start looking for the cause but here's good as any.


Ive a JetDirect box (HP ew2500) I can Telnet to only from a wireless PC, wired nope (95% of the time).


However sometimes it will work for both. Same AP same PCs.

It appears that the JetDirect box negotiates something when it joins that will stop/allow telnet (and browsing to embedded web server) from a wired PC.

Funny thing is, Ping works all the time for both Wired and Wireless PCs.

DHCP is fine

Wireless security has been ruled out


Wireless PC - AP - Switch....Switch - AP - JD Box = OK

Wired PC - Switch....Switch - AP - JD Box = Not Ok (it fails, pretty much 95% of the time.)


And I havent changed any settings.


If Disconnect/reconnect... its pot luck, like I said, most of the time a wired connection will fail, but sometimes Itll work.

I cant see why the Box should treat a wired/wireless PC differently... unless Wireless and Wired traffic is handled differently?..

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Federico Ziliotto Tue, 10/12/2010 - 15:01
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  • Cisco Employee,

Hi Eamonn,


As a very first step, I'd collect a Wireshark trace directly on the PC when connected via wired, so to isolate at which stage of the telnet/http the communication fails.

This would not solve the issue, but it would tell you where it starts failing: for example on the TCP setup process, rather than on the data exchange.


Also, what if you use the following topology?


Wired PC --- swith ... switch --- HP


So without any wireless at all. Does telnet/http still fail?


Hope this helps,


Fede

Cuchullain Wed, 10/13/2010 - 01:26
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Hi Federico,

Ignoring the wireless part of the JetDirect box and using just the Ethernet port all is fine.


Over the last few days I think we have the culprit(s). Either the WCS and/or the WLC's. We installed a new AP (no config) and it allowed devices onto the network at 11mbps. After restarting the JetDirect box numerous times, the connection was fine - wired could telnet etc every single time.

However, when I used... or tried to use... the WCS to config the AP, to give it a name and nominate a primary and secondary Controller, something goes wrong. Only some of the config sticks, its rename. The primary and secondary controller entries fail to save. The AP is down and will accept no devices. Of course when it tried to config, it dropped all devices, including the JetDirect, which switched to another configured AP and voila! No Telnet HTTP from a wired PC.


So... We have a problem. But at least we are narrowing it down. Im not sure how the WCS or WLC could stop a wired PC Telneting to a JetDirect box, but so far thats what it looks like.


Ohhh and Thanks for replying, tis appreciated!!!


Federico Ziliotto Wed, 10/13/2010 - 02:01
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  • Cisco Employee,

Thanks Eamonn,


As far as I could verify in some WLC versions, when we attempt to change the AP name, the AP radios may reset and the WLC is also popping up a message such as "Changing AP name may momentarily disrupt clients connected to this AP".

So this might explain why the print server wireless connection drops while changing the AP name.


Regarding the primary and secondary WLC settings on the AP, we may suspect that the AP is attempting to re-register to the new primary WLC and so it temporarily interrupts the services.


The main recommendation would anyway be to open a TAC case if this requires some more advanced investigations:


http://tools.cisco.com/ServiceRequestTool/create/


Regards,


Fede

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