Wireless Access

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Frequent Contributor I
Posts: 64
Registered: ‎07-16-2014

Expected behavior when client roams across controllers?

I'm in the very early stages of troubleshooting some wireless connectivity complaints, and before I dig in much deeper and open up a support case I wanted to see if I could quickly verify what kind of behavior I should be expected.

 

I have a pair of local controllers set up as an HA pair.  It appears to me that when a user roams from an AP on controller A over to a controller B, no broadcast traffic is explicitly generated by the controllers.  This means that the rest of the upstream network still believes that the client is hanging off of controller A, and sends it there, where it goes off into the void.  This is in contrast to our old Trapeze network, where a broadcast packet of IP protocol 99 was generated whenever a client jumped controllers, keeping the rest of the network in sync.

 

Should I be expecting any kind of similar traffic, like a gratuitous ARP, from my Aruba controllers?

thanks!

MVP
Posts: 1,111
Registered: ‎10-11-2011

Re: Expected behavior when client roams across controllers?

Are the controllers in a mobility domain (L3) or is VLAN mobility (L2) enabled?

You mentioned the controllers are HA.  Do you mean the controllers are configured in an HA group (fast failover) in active/active (dual) mode?

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Frequent Contributor I
Posts: 64
Registered: ‎07-16-2014

Re: Expected behavior when client roams across controllers?

They both share a common VLAN for client connectivity, and if I understand correctly yes, they are in an an active/active HA fast failover group.

MVP
Posts: 1,111
Registered: ‎10-11-2011

Re: Expected behavior when client roams across controllers?

If both locals share the same client VLANs then check the VAP in the ap group, and confirm that VLAN Mobility is checked an IP Mobility is unchecked.

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Frequent Contributor I
Posts: 64
Registered: ‎07-16-2014

Re: Expected behavior when client roams across controllers?

Aha!  That sounds like it's the problem, as both of those settings are flipped the wrong way for me.  I'll get this flipped on the next available maintenence window and report back.  Thanks!

MVP
Posts: 1,111
Registered: ‎10-11-2011

Re: Expected behavior when client roams across controllers?

You're welcome. Hope that solves your issue.
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Frequent Contributor I
Posts: 64
Registered: ‎07-16-2014

Re: Expected behavior when client roams across controllers?

So I haven't had a window to make the change in yet, but as I read more into those settings it doesn't sounds to me like they're my issue.  All VLANs are shared across both local controllers, and all of my clients are always getting dropped into the same VLANs, so my reading of VLAN mobility doesn't sound like it should be necessary.  As for IP mobility, while I do have it enabled on some of my VAPs, all of the IP mobility commands say that it's globally disabled.

 

Does this still sound like something I should focus on?

 

thanks!

MVP
Posts: 4,301
Registered: ‎07-20-2011

Re: Expected behavior when client roams across controllers?

Are you using a VLAN pool on the VAP ?

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Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Guru Elite
Posts: 21,269
Registered: ‎03-29-2007

Re: Expected behavior when client roams across controllers?


fsweetser wrote:

I'm in the very early stages of troubleshooting some wireless connectivity complaints, and before I dig in much deeper and open up a support case I wanted to see if I could quickly verify what kind of behavior I should be expected.

 

I have a pair of local controllers set up as an HA pair.  It appears to me that when a user roams from an AP on controller A over to a controller B, no broadcast traffic is explicitly generated by the controllers.  This means that the rest of the upstream network still believes that the client is hanging off of controller A, and sends it there, where it goes off into the void.  This is in contrast to our old Trapeze network, where a broadcast packet of IP protocol 99 was generated whenever a client jumped controllers, keeping the rest of the network in sync.

 

Should I be expecting any kind of similar traffic, like a gratuitous ARP, from my Aruba controllers?

thanks!


Did you do a test like your client pinging the default gateway while it is roaming, or another wired device pinging your client while it is roaming from controller to controller to observe application performance?

 

IP Mobility (layer 3 mobilty) is not in effect, unless you turn it on globally and it is only used when a controller does not have a layer 2 VLAN that the client's initial controller had.  If it is not configured, it is not active, even when enabled at the Virtual AP level.

 

 Enabling VLAN mobility allows to target controller to look into its bridge table to assign the VLAN of a client that is roaming to it.  If your target controller had a VLAN pool in the VAP and you have Vlan mobility enabled, the controller will assign the VLAN based on the VLAN observed in the target controller's bridge table, instead of a VLAN pool.

 

Again, you should do an actual test where your client is pinging a wired device when it is roaming to determine if you have an issue or not.  Just the client roaming and sending traffic should update the bridge table, due to traffic leaving the controller.



Colin Joseph
Aruba Customer Engineering

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Frequent Contributor I
Posts: 64
Registered: ‎07-16-2014

Re: Expected behavior when client roams across controllers?

Nope - I have my RADIUS servers returning a VLAN name that maps back to a single VLAN.  Here are what I believe are the relevant config fragments:

 

vlan-name Wireless
vlan Wireless 1168

wlan virtual-ap "WPI-Wireless-vap_prof"
   aaa-profile "WPI-Wireless-aaa_prof"
   ssid-profile "WPI-Wireless-ssid_prof"
   vlan wireless
   band-steering
   broadcast-filter all
   auth-failure-blacklist-time 60
   blacklist-time 60
!
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