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Question WLAN and APs

I am very new to the Cisco networking, got my CCNA about a year ago and 1/3 of CCNP.  And I also got bumped from helpdesk to the networking dept.

My question is on the topic of WLANs and their APs.  From what I know (and I can be wrong), a lwapp device will first do a layer3 broadcast to see if there are any WLAN controller that will answer the broadcast.  Or if you have a dhcp option set up, dhcp server answers back with an IP and the ip of the WLAN controller.  That's what I know. 

I've checked the dhcp server and we don't have that option setup.  So the IP address for the WLAN controller must be some how configured manually.  (The WLAN controller and the APs are in different subnets).  My question is I SSH'ed into the APs, looked at the running config and there was no mention of an IP matching the WLAN controller.  Where would I find that information?  Is it stored somewhere else? 

And if anyone's wondering, the wireless network was setup a few years ago by a consultant and unfortunately, no documentation was left behind. 

**Also there doesn't seem to be a start-config.  I had another spare AP (1231g) and when I wrote erased it, it still kept the running-config.  Are the APs set up differently?  My understanding of Cisco switches and routers was that the start-config gets loaded after a reload and the running-config runs on memory and gets erased/lost after a reload.

*** And lastly, there doesn't seem to be a copy command for me to download/upload an IOS image?  the IOS version is

Version 12.4(21a)JHA

Thank you.

3 REPLIES

Question WLAN and APs

For the lightweight AP, you don't have direct access to the configs.  to show the WLC that an AP is aware of you would issue the command - show capwap client rcb.  All config is pushed from the WLC as well as the OS that is running on the AP.

For the AP join, there is a layer 2 broadcast, DHCP option 43, DNS, OTAP, and the AP goes through all of them before it picks a WLC to join.

Steve

HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
New Member

Question WLAN and APs

When you say that the OS is also pushed to the AP, does that mean it overwrites the current IOS?  Or does it download it to a temp location and then load it?

As for the AP join, it's not layer 2 broadcast (WLAN is on a different subnet), not DHCP option (not set), not DNS (the name of the WLAN is not set to be that) and I don't think we're doing OTAP.

So in that case, can it be configured through via http?

Thanks.

Question WLAN and APs

So normally, the AP will pull it's code from the WLC, install it in flash, and reboot.  When it comes up it is on the new IOS image.

As for the AP join, take a look at the L3 device config, it could be that it is using a forward for ports 5246/5247 and an IP helper-address to point to the WLC.

it could also be that whomever installed the AP joined them to the WLC them changed what VLAN the AP is on.  At that point, the AP will try to join the last WLC that it was successfuly joined to.

Steve

HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
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