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Archive for April, 2012

FlexConnect APs – Some Thoughts

I’m working on a project that requires FlexConnect APs. As part of the project, I’ve run into a few pieces that took a bit to figure out, as they weren’t readily apparent to me.

FlexConnect ACLs

I understand your typical WLC ACLs.  Everything for non-CPU ACLs was from the perspective of the WLC to and from the client.  So, inbound was from the client to the WLC.  Outbound was from the WLC to the client.  And, just make sure that if you have a deny all at the end, you have a permit for both directions of the flows that you want to allow.  No problem.

FlexConnect ACLs appear to take a different approach. I made the (apparently erroneous) assumption that “ingress” (note the change in terminology) was from the client to the AP, while “egress” was from the AP to the client.  Au contraire!  “Ingress” means from the wired side/switch to the AP, while “egress” means from the AP to the wired side/switch.  In this case, I wanted to ensure that guests could only get to external IP addresses.  Applying an ACL that basically denied anything to the 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 subnets while permitting everything else INGRESS blocked my traffic.  Once I applied it EGRESS, everything worked as expected.  I could also apply the inverse ACL ingress, but that wasn’t necessary in this case.

FlexConnect and Local External RADIUS

Way back in my day, if you wanted to use RADIUS with H-REAP, you had to send it back through the WLC.  Then, Cisco added this new-fangled feature of a Backup RADIUS server as part of H-REAP groups, where the AP could go to authenticate users if the WLC was down.  But, what if I want to use a local RADIUS server (say an ACS or Windows NPS server at a site)?  That is where the checkbox “FlexConnect Local Auth” comes into play.  When checked, RADIUS requests will be sent from the AP to either the default RADIUS authentication server(s) of the WLAN OR the primary/secondary RADIUS server(s) of the FlexConnect group (if defined).  The FlexConnect group configuration takes precedence over the WLAN configuration.  Note that the RADIUS server needs to be configured to allow the AP as a NAS, using the shared key defined by the RADIUS server configuration on the WLC.  Also, if using an external RADIUS server, you can ignore the “Enable AP Local Authentication” checkbox under the FlexConnect group configuration.  That’s used if the AP itself will be the RADIUS server. (Thanks to Mr. @revolutionwifi for his article at http://revolutionwifi.blogspot.com/2011/09/cisco-h-reap-local-authentication.html for pointing me in the right direction there!)

FlexConnect and ISE

In looking at the literature, one would assume that FlexConnect APs won’t work with ISE at this point (WLC 7.2 and ISE 1.1).  That is not completely true.  You can configured ISE as a AAA server for RADIUS, similar to how ACS 5.X (not including 5.0) is configured.  The interface is a bit different from ACS, but many of the concepts apply.

I’m sure that there will be more things with FlexConnect in the future.

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