WIFITECHBLOG

I ran into an interesting problem last Monday (02/01/10) at work - someone had deployed APs at a remote location and configured them as autonomous APs. I performed a quick lightweight upgrade on them, and made the mistake of leaving static IPs on them.

The upgrade tool asks for your WLC address so I thought that would prime the APs with that address for the controller... Wrong. As soon as the APs booted to their lightweight IOS (the standard recovery image) I lost connectivity with them (no DHCP so option 43/60 is not available. APs are on a different domain than the switch - why it kept this but not snmp and passwords is irritating - so controller DNS didn't work). Passwords were of course reset, so telnet/ssh responded with "password required but none set." SNMP was also reset... I thought I had lost connectivity to them and would be required to ship out new APs!

In reviewing some of the Cisco literature, though, I found a cool little workaround. You can set the IP helper-address to the IP address of the controller, and then use the "forward protocol" command to forward all CAPWAP/LWAPP traffic to the IP helper-address, i.e. the controller (protocols 12222, 12223 for LWAPP and 5246, 5247 for CAPWAP)! Once connectivity was re-established to the APs, I set them to DHCP and removed the forward protocol commands and set the IP helper-address back to the DHCP server. Problem solved without sending new APs!

I've been reading the 802.11 Wireless LAN Fundamentals recently, just while traveling. It's not sinking in too well, really, but I'm slowly making some connections with real-world applications. They're few and far between, though. Studying the wireless physical layer isn't high on my priority of learning, but I guess it makes a good cornerstone...

A more pressing wireless question I've come up with is AP fallback mode. I would like all the APs on our network to be setup in Local mode so that they aren't overutilising their resources and creating a lot of heat in the process. However, because of our network configuration, we don't have backup WLCs in each location we have wireless deployed. So in order to get the APs to work properly in fallback mode, I think we're going to have to deploy them all in H-REAP.

Basically, I would like to keep the APs in Local mode unless they need to failover, in which case I'd like them in H-REAP. Since that's not possible, I have 2 options:

1. Keep the APs in Local mode 100% of the time. The drawback here is that when the APs failover, they tunnel all the traffic across our WAN to the closest WLC, but take up a lot of the bandwidth doing so. Also, the clients are forced to get IPs from a site across the WAN, which ultimately disrupts some of the applications they are able to access since they are hitting the firewalls with different IPs.

2. Keep the APs in H-REAP. This forces the APs to do the client authentication, association, etc., and forces them to use more resources thus giving less throughput to the clients. Plus, everything I'm reading says it isn't recommended except for remote sites where it's not cost effective to place a controller.

We had set everything to H-REAP. I think now, though, that we should have all APs deployed in Local mode and just recognize that if a controller fails, the clients won't have connectivity, or might not be able to access all their applications.

So, here's the deal.

The Location Appliance is finally working with WCS. What did I do to get it working? I followed a suggestion at this site:

http://supportwiki.cisco.com/ViewWiki/index.php/Unable_to_add_a_Wireless_Location_Appliance(WLA)_to_a_Wireless_Control_system(WCS)

Namely, step 4. I guess I had been assuming this whole time that I had changed the HTTPS username/pass... Nope. It was default. D'oh! I still had to check the HTTPS box though, since the 2710 still isn't responding to HTTP. Now, to get it synchronized with the WLCs!

For the past couple of days, I've been working on configuring a 2710 Location Appliance. Our division got it used from another division, so I had to start by resetting the root password. I've attempted reconfiguration manually, and when that failed, I've run the automatic setup script. I've also updated the code to 6.0 (I know; it's not the version that is going to be on the CCIE lab, but it's the version of code that we're running on our network here).

It's been a good refresher of using Linux and VI to edit the setup and find files. I'm still not 100% complete, but feel I'm making good progress. The 2710 is back online from its most recent reboot, so back to work!

I posted this on my personal blog by mistake, so now it's in 2 places...

This past week (June 28 - July 3) I was able to attend the Cisco Live! 2009 Conference in San Francisco; what a treat! While taking in as many classes as I could (I only missed a single session!) and enjoying the afterhours social activities, I also managed to take the final test in my CCNP certification! Yeah! I passed the ONT test (642-845) with an 89% to complete my CCNP. The first 5 questions threw me for such a loop that I didn't think I would pass... Things got better from there, however, much to my pleasure :)

I spent the next few days trying to decide where I see myself progressing (or digressing, gasp!) from here. After much seeking, I've decided that the CCIE Wireless will be the way to go. While I feel the CCIE Routing and Switching is probably more applicable to the networking world as a whole, I also think that the Routing and Switching exam could cover a lot more material, where the Wireless seems a bit more focused. And, there's absolutely nothing stopping me from going for the Routing and Switching once I have Wireless under my belt!

I made a few key contacts while at Cisco Live! that I'm hoping to follow up on - people who are also interested in obtaining their CCIE Wireless certs. Hopefully I'll be blogging in the days to come about my progress on that front.