[Samba] New sparsely connected replica graph (Improved KCC)

[James]

On 9/18/2015 1:27 AM, Garming Sam wrote:
> Hi,
>
> First of all, thanks for at least giving it a go. I think there's a
> few points of confusion though. Bridge all site links is enabled by
> default and should be enabled, otherwise you would need to manually
> specify site-link bridges (which is not recommended by Microsoft and
> not implemented in the KCC currently).
>
> Is the new KCC running on all the DCs you mention?
>
> Denis Cardon had a go briefly and found that he needed to specify a
> bridgehead before any connections were made. We weren't able to
> confirm, but it's possible that specifying a bridgehead may help.
>
> http://samba.2283325.n4.nabble.com/More-KCC-patches-td4687011.html
>
> So now to your topology, you mentioned that those connections should
> not have been removed? Do you have any specific reasons why? If
> everything was functioning, there should be even more connections
> missing than you see right now. The general idea of using the topology
> is to make sure that a site contains only 1 in and 1 out link across
> all the DCs within that site (as well as additional links within a
> site). The fact that everything was connected before was the cause of
> bandwidth issues.
>
> The following would be similar to what I would actually expect:
>
> SITEA
>   Servers
>        SDC1
>           NTDS Settings   SDC2
>
>        SDC2
>           NTDS Settings   SDC1
>                           PDC1
>
> Default-First-Site-Name
>   Servers
>        PDC1
>           NTDS Settings   PDC2
>                           DDC1
>                           SDC1
>        PDC2
>           NTDS Settings   PDC1
>
> SITEB
>   Servers
>        DDC1
>           NTDS Settings   DDC2
>                           PDC1
>
>         DDC2
>           NTDS Settings   DDC1
>
>
> Probably one of the most annoying things about replication and testing
> replication is that it doesn't necessarily trigger immediately. It's
> definitely not something which is straightforward to test, or implement.
>
> Cheers,
>
> Garming
Hello Garming,

    I was creating site link bridges and that was leading to some
confusion. That helps me moving forward in testing.

Yes the new KCC was enabled on all DC's across all sites.

Specifying a bridgehead server is what I want to avoid. If I was to
specify one I would expect to find the topology you mentioned. It's my
understanding only one DC in a site can be set as a bridgehead server.
My goal was to configure specific site to site replication. If the
bridgehead server goes down I lose site to site replication. It's
starting to sound like want I want to achieve is currently not supported
by Samba( site-link bridges).

This is the topology I'm going for,

SITEA
  Servers
       SDC1
          NTDS Settings   SDC2
                                     PDC1
                                     PDC2
       SDC2
          NTDS Settings   SDC1
                                     PDC1
                                     PDC2

Default-First-Site-Name
  Servers
       PDC1
          NTDS Settings   PDC2
                                     DDC1
                                     DDC2
                                     SDC1
                                     SDC2 
                                    
       PDC2
          NTDS Settings   PDC1
                                     DDC1
                                     DDC2
                                     SDC1
                                     SDC2

SITEB
  Servers
       DDC1
          NTDS Settings   DDC2
                                     PDC1
                                     PDC2       

        DDC2
          NTDS Settings   DDC1
                                     PDC1
                                     PDC2

I will give it a go this weekend and leave the new settings in place for
a day and half and monitor the changes the KCC makes. I will try with
and without specifying a bridgehead server.  This way I have some data
to report that may be helpful to others if not myself. Thanks.

-- 
-James