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Broadcast Multicast ( BCMC ) Bonjour Problem

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  • 1.  Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 09:55 PM

    We are a K-12. Our wired network is divided into two huge /16 subnets.  Secondary Blocks are 172.16.0.0 / 16 and Primary has 172.17.0.0 / 16.  Block = Building.

     
    Secondary School is mainly in blocks 1, 2,3, (... 4 admin)
    Primary School is located in blocks 5,6,7
     
    Our present Aruba setup goes like:
     
    SSID   / VLAN  / Broadcast Multicast (BCMC) on SSID Level
     
    Guest SSID  / 172.20.0.0 / 16 / DROPPED
    Student SSID  / 172.21.0.0 / 16  / ALLOWED
    Staff SSID  / 172.22.0.0 /16   /  DROPPED
    BYOD SSID  / 172.23.0.0 / 16 / DROPPED
     
    So regardless of your location, whether you are in Block 1 or Block 6, if you are connected to Staff SSID, you will be GRE-tunneled into 172.22/16 range. So if Bonjour is on, Apple TVs in Primary Block can be seen by computers in the Secondary.
     
    Secondary school has around 900 Macbook Pros and ~200 iOS devices. 
    Primary school has  500 Macbook pros and ~500 iOS devices. 
    Our concurrent client count max out at around 1,500. 
     
    Most of Primary School is connected to Student SSID while Secondary is in Staff SSID (for both student and staff devices).
     
    BCMC is ALLOWED in Student SSID and DROPPED for the rest. The moment we ALLOW BCMC in Staff  SSID, instantly our network will come crashing!  Ping time outs, server unreachable, error rates on our switches goes to the roofs! And this affects both wired and wireless clients. 
     
    Basically for Secondary School, Bonjour is not readily available as their laptops are configured by default to connect to Staff SSID, they have to switch to Student SSID if they want to use Airplay or any other Bonjour services. 
     
    Our APs are mixed of AP121, AP105 and AP61 (very few AP125 and AP135). Total inventory of around 140. 
     
    Our core and distribution switches are CISCO. Besides storm control on the CISCO switches, is there a particular BCMC setting that we can tweak to help us with our present situation?Our core switches are 45xx and distribution switches are 29xx. 
     
    Cheers,
    Marlon


  • 2.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    EMPLOYEE
    Posted Oct 07, 2013 10:13 PM

    Why are you not dropping broadcasts on all Virtual APs or putting BCMC on all VLANs?



  • 3.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:19 PM

    We are a heavy Mac shop. We need Bonjour to work.  We have iPad apps that will never work if broadcast/multicast is disabled on SSID level. Hence, our workaround is to enable it on at least one SSID.

     

    We tried BCMC optimization on VLAN level, but the moment we put it on, the entire network  went down to the point we even have to connect a console cable just to revert the setting, because the WEB GUI was inaccesible.   :( 



  • 4.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    EMPLOYEE
    Posted Oct 07, 2013 10:24 PM

    You would need to run a Airgroup-Enabled version of ArubaOS (6.3.x and above) so that you can have drop broadcasts on, but still use bonjour applications.  Your VLANs are too large and have wired clients, so you have no choice but to have drop broadcasts, or VLAN BCMC optimization on, because broadcasts would degrade your wireless network otherwise.

     

    I would wait for 6.3.1.0, which should be coming out soon with some fixes.



  • 5.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:29 PM

    We are still on 6.1.3.   Maybe an upgrade would help. 

     

    Thanks cjoseph!  As always your inputs are highly regarded. 



  • 6.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:31 PM
    @cjoseph wrote:

    You would need to run a Airgroup-Enabled version of ArubaOS (6.3.x and above) so that you can have drop broadcasts on, but still use bonjour applications.  Your VLANs are too large and have wired clients, so you have no choice but to have drop broadcasts, or VLAN BCMC optimization on, because broadcasts would degrade your wireless network otherwise.

     

    I would wait for 6.3.1.0, which should be coming out soon with some fixes.

    I am working with another organization that simply does not understand this at all.... They are a large mac location with over  2500 wired and wireless devices all on a single subnet (that also includes all of their management stuff as well) and they keep complaining about connectivity issues, but just blame the hardware... It really does drive me crazy...



  • 7.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    EMPLOYEE
    Posted Oct 07, 2013 10:32 PM
    @danstl wrote:
    @cjoseph wrote:

    You would need to run a Airgroup-Enabled version of ArubaOS (6.3.x and above) so that you can have drop broadcasts on, but still use bonjour applications.  Your VLANs are too large and have wired clients, so you have no choice but to have drop broadcasts, or VLAN BCMC optimization on, because broadcasts would degrade your wireless network otherwise.

     

    I would wait for 6.3.1.0, which should be coming out soon with some fixes.

    I am working with another organization that simply does not understand this at all.... They are a large mac location with over  2500 wired and wireless devices all on a single subnet (that also includes all of their management stuff as well) and they keep complaining about connectivity issues, but just blame the hardware... It really does drive me crazy...

    "It works on wired just fine"....

     



  • 8.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:33 PM
    @cjoseph wrote:
    @danstl wrote:
    @cjoseph wrote:

    You would need to run a Airgroup-Enabled version of ArubaOS (6.3.x and above) so that you can have drop broadcasts on, but still use bonjour applications.  Your VLANs are too large and have wired clients, so you have no choice but to have drop broadcasts, or VLAN BCMC optimization on, because broadcasts would degrade your wireless network otherwise.

     

    I would wait for 6.3.1.0, which should be coming out soon with some fixes.

    I am working with another organization that simply does not understand this at all.... They are a large mac location with over  2500 wired and wireless devices all on a single subnet (that also includes all of their management stuff as well) and they keep complaining about connectivity issues, but just blame the hardware... It really does drive me crazy...

    "It works on wired just fine"....

     

    Bingo - therefor it must be the wiress network....  I just tell them to replace all their switches with hubs and then get back to me ;)



  • 9.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:49 PM
    I'm glad you are acknowledging how large broadcast domains are bad regardless of vendor. I agree. There seems to be a philosophy manifesting inside Aruba that one (or more) large subnets be used for clients and to just let the controller filter things out.


  • 10.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    EMPLOYEE
    Posted Oct 07, 2013 10:53 PM
    @Ryan wrote:
    I'm glad you are acknowledging how large broadcast domains are bad regardless of vendor. I agree. There seems to be a philosophy manifesting inside Aruba that one (or more) large subnets be used for clients and to just let the controller filter things out.

    To be clear, large subnets work just fine on an Aruba WLAN if you have broadcast controls in place.  You cannot however expect to not have broadcast filtering in place and have the same performance.  If bonjour applications are required, you run Airgroup.



  • 11.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 07, 2013 10:59 PM
    @cjoseph wrote:
    @Ryan wrote:
    I'm glad you are acknowledging how large broadcast domains are bad regardless of vendor. I agree. There seems to be a philosophy manifesting inside Aruba that one (or more) large subnets be used for clients and to just let the controller filter things out.

    To be clear, large subnets work just fine on wireless if you have broadcast controls in place.  You cannot however expect to not have broadcast filtering in place and have the same performance.  If bonjour applications are required, you run Airgroup.

    I think large wireless only subnets are OK, the main issue seems to be related to subnets that span wired and wireless devices - then you start having some issues when you dont do something with your broadcasts.  I have seen wifi networks where 60% of the traffic was broadcasts because of this configuration...  And the admins still had no idea why this was happening....

     

    It is a frustrating issue, that is easily corrected, and in my opinion manageable subnets just make things easier for everything. 



  • 12.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    EMPLOYEE
    Posted Oct 07, 2013 11:15 PM

    I think large wireless only subnets are OK, the main issue seems to be related to subnets that span wired and wireless devices - then you start having some issues when you dont do something with your broadcasts.  I have seen wifi networks where 60% of the traffic was broadcasts because of this configuration...  And the admins still had no idea why this was happening....

     

    It is a frustrating issue, that is easily corrected, and in my opinion manageable subnets just make things easier for everything. 

    Danstl,

     

    You can have wired and wireless in the same VLAN as long as you ensure that you drop/control broadcasts on ALL WLANs, and it will certainly work.  You do NOT want to have them in the same VLAN because it seriously complicates troubleshooting.  Running a large subnet WLAN without broadcast controls more often that not makes it unusable.  It just gets worse when you add wired traffic.

     

    Recap:

    - Your users can keep their large subnets, even with wired clients as long as you enable broadcast controls.

    - The downside is that it complicates troubleshooting when wired and wireless are in the same VLAN

    - If those users run bonjour applications, they can run Airgroup code, where you can do that with broadcast controls, and it will work.

     



  • 13.  RE: Broadcast Multicast ( BCMC ) Bonjour Problem

    Posted Oct 08, 2013 08:57 AM
    Once a client's packet is decapsulated at the controller and (assuming the destination is not local to one of the controller's tunnels) is forwarded out the controller's uplink to the distribution layer, does the controller filter these broadcasts? Or, does it only filter broadcasts towards the controller (not away)? My understanding was that the filtering occurs in the direction towards the client, not away from the client.