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Roaming between 2 clusters in 8.10.x.x

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  • 1.  Roaming between 2 clusters in 8.10.x.x

    Posted Jun 07, 2024 08:21 AM

    Good morning all.

    I have an issue that I can't seem to get to the bottom of.  High level, clients cannot roam between APs on different controller clusters.  Below are the gritty details.

    Scenario - campus setup with 2 clusters (4 controllers on each cluster) geographically separate.  Each cluster has it's own management network, but the devices (WLANs) are on the same L2 network.  There are a few areas where the RF domain from APs in each cluster overlap.  This is where my issue is.  When a user is connected to an AP on Cluster A and walks to an area serviced by an AP on Cluster B, the device moves to the new AP but shows as "connected with no internet".  The IP address of the device does not change since the L2 for that WLAN is the same across both clusters so I don't think I need to (or should) enable IP Mobility (but I could be wrong there) and I don't think 802.11k would help.  The only fix for the end user is to disconnect and reconnect the wifi.

    I understand that seamless roaming is only between APs in the same cluster and I'm OK if the device needs to re-authenticate (voice over IP roaming isn't a high priority in this scenario).  I just need the device to connect again automatically.

    Any ideas?

    Thanks!

    Jeff



  • 2.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 07, 2024 12:49 PM

    You can try enabling this parameter in the Virtual AP profile:

    fdb-update-on-assoc

    That would send out a gratuitous ARP when a client enters the forwarding table to ensure that the switch infrastructure is updated:

    fdb-update-on-assoc



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    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 3.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted Jun 10, 2024 08:07 AM

    Thank you Colin!  that looks like exactly what I'm looking for.  I will be giving it a try this week.




  • 4.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted Jun 26, 2024 07:34 AM

    I was finally able to get a change window for this.  Unfortunately it did not correct the issue.  Any chance the APs need to be re-provisioned with the VAP after making this change?  I changed the VAP but did not re-provision any APs.




  • 5.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 26, 2024 07:38 AM

    They do not.  Try checking "show user-table verbose" on the target controller to make sure the vlans are the same 



    ------------------------------
    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 6.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted Jun 26, 2024 08:47 AM

    They are both using a VLAN pool of 4 subnets, but the pools, pool name, subnets, etc are all identical across both clusters.




  • 7.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 26, 2024 08:56 AM

    VLAN pools can be hashed differently if controllers are not in the same clusters.  That is why I mentioned checking the VLAN of the client when it ends up on the target controller. The definitive way to deal with this is to have a single user VLAN across controllers and use broadcast suppression like suppress-arp and BCMC optimization.



    ------------------------------
    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 8.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted Jun 26, 2024 08:53 AM

    And I verified that the device IP address is not changing when roaming from one cluster to another.  IP stays the same, device shows "connected no internet", and just need to disconnect/reconnect to bring it back.  I will be opening a TAC case for this at some point soon, but I'm dealing with a more pressing issue with them and this is a low priority.  It's currently only effecting one small area of our campus where wifi coverage overlaps from one cluster to the other.  But we are expanding our outdoor wireless so this will start happening in more locations.  I appreciate all of the help!!!




  • 9.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 26, 2024 09:01 AM

    I am answering your posts out of sequence so I apologize.  We probably need to do debugging on the target controller for the test user to find out the sequence of events. I'm not going to bore you with detailed steps that I would take to figure this out, but in general a debug should give us some clues.



    ------------------------------
    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 10.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted Jun 26, 2024 09:33 AM

    Thanks again Colin.  No worries about answering out of order - I posted multiple times out of order so replies that way are expected (my fault).  Quick question - currently the VLAN pools are 4 subnets, each a /20 due to possible number of clients at a time.  This was done a few years ago.  Not entirely sure why it was set up this way except maybe it started to grow and additional subnets were added (and they are not all contiguous) as the population grew.  Would it help to set up a single /18 vlan instead of a vlan pool?  Or would that be too large for a single VLAN and cause other issues?  I will be opening a TAC case in a week or so after I get the other issue under control.




  • 11.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 26, 2024 09:52 AM

    Growth is probably the answer as to why.

    Setting up a single/18 is  dependent on the size of the cam  table that can be handled by your layer 2/3 infrastructure.  That is the biggest hurdle there.

    We might be able to figure out why roaming is not working seamlessly before we have to do that, however.



    ------------------------------
    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 12.  RE: Roaming between 2 clusters in 8.10.x.x

     
    Posted Jun 26, 2024 05:23 PM

    I asked a few questions, and....

    The "preserve-vlan" option in the Virtual-ap is designed to do what you need.  Here is how it is described:

    "If the 'preserve-vlan' knob is enabled for a 'virtual-ap', the controller can try to retain the VLAN ID for the client by looking up the client MAC in the bridge table. If the entry is found, the controller will retain the VLAN for the client. If an entry is not found, the controller may allocate a new VLAN ID for the client."

    I would try "preserve-vlan" in the virtual-ap profile first before trying a large vlan.



    ------------------------------
    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card
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  • 13.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 4 days ago

    hi.. did you get a solution for your original problem? i'm also facing the same one, exactly the same, even with an open ssid.  It would be really helpful to know where you landed with this design of 2 clusters and roaming between them.




  • 14.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 4 days ago

    Hello sol_jee

    "hi.. did you get a solution for your original problem? i'm also facing the same one, exactly the same, even with an open ssid.  It would be really helpful to know where you landed with this design of 2 clusters and roaming between them."

    I did not, but I have not had a chance to try the preserve-vlan option that Colin mentioned above.  This is a very low priority for me since there is only one location where the APs connected to different clusters can overlap.  We are a college campus divided by a road right down the middle and we have a cluster on each side of the street serving half of the APs for redundancy (with capacity to fail over all APs to either cluster).  There is only one location for now that has an outdoor AP that is close enough to the street for a user to roam.  If I get a free weekend I will try the preserve-vlan option and get back to you.




  • 15.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 4 days ago

    Thank you !

    In my case, everything is exactly the same! except that i have a single vlan with a single pool across both the clusters. Still i do see the same behavior. So i'm not too sure if the preserve-vlan would help. Anyways i would wait for your test results. 




  • 16.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 4 days ago

    Don't hold your breath - Like I said this is a low priority for me at the moment LOL.  I honestly thought enabling the GARP (Gratuitous ARP) would correct it.  When looking at the controllers and airwave, I see the device roaming as it should.  But it just goes to neverneverland until it is disconnected and reconnected.  To me that's saying that the switch on the back side still has an incorrect path for the device and an ARP request should fix that.  Like you, I'm not that sure the the preserve-vlan will help because I don't see the users vlan changing, but I'm willing to try anything if it will help.




  • 17.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted yesterday

    Thanks ! .. will be watching this thread :-) 

    An interesting observation when i did a debug for a user; the controller is dropping packets as as its not assigned via dhcp

    authmgr[3964]: <522026> <3964> <INFO> |authmgr|  MAC=30:d7:a1:xx.xx.xx IP=192.168.21.1 User miss: ingress=0x1091b

    authmgr[3964]: <522141> <3964> <DBUG> |authmgr|  30:d7:a1:xx.xx.xx IP 192.168.21.1: drop pkt as ip not assigned through dhcp.

    Yes i have enforce dhcp set on the aaa profile. Not too sure if i should take it out just to solve this use case.




  • 18.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 20 hours ago

    ArubaOS 8 have any mechanism for sharing the status of a dhcp-exchange for a client between controllers ?




  • 19.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 2 hours ago

    I would say that disabling that setting is worth trying.

    I'm not aware of a sync of dhcp issued IP-mac mappings between controllers in different clusters. Roaming between clusters is something that should be avoided, and not a standard scenario.



    ------------------------------
    Herman Robers
    ------------------------
    If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
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  • 20.  RE: Roaming between 2 clusters in 8.10.x.x

    Posted 54 minutes ago

    Thank you.. will try it out during a weekend.