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KCC generated connections

    Frage

  • Hi,

    I'm not sure whether this is an issue or not.

    I had two Windows Server 2008 Standard servers acting as DC/GC/DHCP/DNS one at each remote site connected over an IPSEC WAN tunnel.

    Each server saw the other as it's replication partner under NTDS settings.

    They have been working faultlessly for several years now.

    Recently I had to set up a third site and add another DC/GC/DHCP/DNS to that third site to replicate with the other two existing sites.

    This third server, and wondering if this might be the cause, is a Windows Server 2008 R2 server, the other two are just Windows Server 2008.

    I've setup the third site in ADSS and have got the new third server up and running, had to upgrade the schema on the existing DC's etc..

    However there is something that is troubling me, possibly unnecessarily so..?

    It appears that the new third site (Site C) lists both the DC (SERVER_A) at the first site (Site A) and the DC (SERVER_B) at the second site (Site B) under NTDS automatically generated connections..

    Site C
           Servers
                     SERVER_C
                                    NTDS Settings : <automatically generated> SERVER_A
                                                            <automatically generated> SERVER_B

    so far so good..

    But the first site (Site A) no longer shows an automatically generated connection for the DC (SERVER_B) from the second site (Site B), it now only shows and automatically generated connection for new Windows Server 2008 R2 server (SERVER_C) from the new third site (Site C)

    Site A
           Servers
                    SERVER_A
                                   NTDS Settings : <automatically generated> SERVER_C

    And similarly under NTDS settings on the second site (Site B) it also no longer shows an automatically generated connection for the DC (SERVER_A) from the first site (Site A), and it now also only shows and automatically generated connection for new Windows Server 2008 R2 server (SERVER_C) from the new third site (Site C)

    Site B
           Servers
                    SERVER_B
                                 NTDS Settings : <automatically generated> SERVER_C

    They do all appear to be replicating OK.

    I've made changes to items in Active Directory in SERVER_A at Site A and this does appear to get replicated to SERVER_B at Site B, though I suspect that this only occurs after Site A has replicated to Site C and then Site C has subsequently replicated back to Site B.

    I'm just wondering at to whether or not the KCC ought to be generating connections for Server_B at Site A and also Server_A at Site B as it was previously before I added the new Site C ?

    Geographically Site C is a long way away from Site's A and B, on a different continent altogether and should have a slower connection also.

    Should I be concerned about any of this seeing as it does appear to be working ?

    J.

     

     

     

     


    • Bearbeitet Jim_1235 Montag, 23. Januar 2012 13:29
    Montag, 23. Januar 2012 13:27

Antworten

  • Hello,

    as you are using the default settings let it work as it is except you have errors, which i didn't realize from your question.

    The KCC will take all correct settings, more details in:

    http://blogs.technet.com/b/markmoro/archive/2011/08/05/you-are-not-smarter-than-the-kcc.aspx


    Best regards Meinolf Weber Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.
    Montag, 23. Januar 2012 18:10
  • Great to hear you got what I was trying to say in the previous post.

    Since C was acting as hub and hence there was a delay.Now the topology is correct.

    Yes,you can create Site link from SiteB--SiteC with higher Cost.

    Hope this helps....


    Best Regards,

    Sandesh Dubey.

    MCSE|MCSA:Messaging|MCTS|MCITP:Enterprise Adminitrator | My Blog

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

    • Als Antwort markiert Jim_1235 Sonntag, 18. März 2012 16:41
    Samstag, 17. März 2012 20:45
  • Are you sure? You said, the link across the atlantic is slower than the connection between site A and B?

    In case, the line across the Atlantic is slower, you should create one sitelink (i.e. named "ATLANTIC-A")an add site A and C. Set costs to 200. You can also increase/decrease the replication intervall, but you can let them by default (180 min) because it already works. Check the DEFAULTIPSITELINK, the costs should be 100 and only contains site A and site B. If you have a line from site B to site C, too, you can also create a sitelink (i.e. named "ATLANTIC-B") with costs 200.

     

    When the KCC now checks the replication connections you will have the following connections:

    Server A: <automatically generated> SERVER_B; <automatically generated> SERVER_C

    Server B: <automatically generated> SERVER_A, <automatically generated> SERVER_C

    Server C: <automatically generated> SERVER_A; <automatically generated> SERVER_B

     

    Kind regards,

    M.Hivner

    Montag, 23. Januar 2012 20:03
  • From the current site topology you have hub and spoke tropology and Site C is acting as hub site.Hence the changes made in site A will be replicated  to siteB when siteB replicate with siteC.

    The current site link is created as below

    Site link1:SiteC----SiteA
    Site link2:Site C---SiteB

    Since Site C has low bandwidth( across the Atlantic and connects via a DSL cable connection 15mbps speed) I would recommend to delete the existing site link and create new site link as below.

    Site link1:
    SiteA--SiteB and define the replication schedule and cost as per requiremet.

    Site link2:
    It could be from siteA to SiteC or from SiteB to SiteC depending upon the n/w bandwidth between the sites and define the cost and schedule depending upon the n/w bandwidth and business requirement.

    Once done you need to run repadmin /kcc & repadmin /syncall/AdeP on all DC to generate the required topology.

    Hope this helps

    Regards,
    Sandesh Dubey.
    -------------------------------
    MCSE|MCSA:Messaging|MCTS|MCITP:Enterprise Adminitrator
    My Blog: http://sandeshdubey.wordpress.com
    This posting is provided AS IS with no warranties, and confers no rights.



    • Als Antwort markiert Jim_1235 Sonntag, 18. März 2012 16:41
    Dienstag, 24. Januar 2012 09:14

Alle Antworten

  • Hi,

    it seems you don't have configured the costs of the sitelinks right, or is your new site on the same sitelink?

    How is your replication topology? You should create sitelinks in AD for each connection between your sites.

    Regards

    M.Hivner

    Montag, 23. Januar 2012 14:31
  • Hi,

    Can you check by repadmin/replsum to find out if there are any replication errors. Do you have a site link which is configured between Site A and Site B, Site A and C? At what replication interval?

     


    Regards, Mohan R Sr. Administrator - Server Support
    Montag, 23. Januar 2012 14:57
  • Hi Folks,

    I only have one sitelink DEFAULTIPSITELINK

    ..I guess this is where it's going wrong perhaps ?

    Should I have more than one then if I have more than two sites ?

    repadmin /replsum returns:

    Source DSA           largest delta              fails/total   %%  errors
    SERVER_A              30m:53s                    0  /       5       0
    SERVER_B              30m:55s                    0  /       5       0
    SERVER_C              27m:13s                    0  /     10       0

    Destination DSA   largest delta                fails/total %%    errors
    SERVER_A               26m:24s                   0  /        5      0
    SERVER_B               27m:13s                   0  /        5      0
    SERVER_C               30m:56s                   0  /      10      0


    J.

     

     

     

     

    Montag, 23. Januar 2012 17:33
  • Hello,

    as you are using the default settings let it work as it is except you have errors, which i didn't realize from your question.

    The KCC will take all correct settings, more details in:

    http://blogs.technet.com/b/markmoro/archive/2011/08/05/you-are-not-smarter-than-the-kcc.aspx


    Best regards Meinolf Weber Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.
    Montag, 23. Januar 2012 18:10
  • Should I have more than one then if I have more than two sites ?

    Yes! You wrote site C is only a slow link. If you configure more sitelinks you can configure costs for each links and the replication intervall. You should configure the costs to site C higher than the costs from site A to B. So i.e. you can prevent clients from site B to query your DC on site C. If you tell me, which real connections between your sites you have, i can give you an suggestion.

    Back to your question at the beginning. In Active Directory the KCC (Knowledge Consistency Checker) generates the connections automatic, optimized for the appropriate situation. In default each DC performs this recalculation every 15 minutes. In fact changes from site B where replicated to Site C first and then to site A. Don´t worry, in your case there aren´t any errors woth your replication, but you should configure sitelinks, so you can reduce traffic over the slow connection to site C.

    Hope this helps,

    M.Hivner

    Montag, 23. Januar 2012 19:04
  • Thanks guys, like I said it does appear to work OK, I just thought that the R2 version of Windows Server 2008 brought something new to the party which was causing this behaviour.

     

    Site A and Site B connect over a dedicated 10mbps leased line.

    Site C is across the Atlantic and connects via a DSL cable connection. 15mbps I think.

    How many additional sitelinks should I use to be able to control this in a better manner ? one more or two more ?

    J.

     

    Montag, 23. Januar 2012 19:44
  • Are you sure? You said, the link across the atlantic is slower than the connection between site A and B?

    In case, the line across the Atlantic is slower, you should create one sitelink (i.e. named "ATLANTIC-A")an add site A and C. Set costs to 200. You can also increase/decrease the replication intervall, but you can let them by default (180 min) because it already works. Check the DEFAULTIPSITELINK, the costs should be 100 and only contains site A and site B. If you have a line from site B to site C, too, you can also create a sitelink (i.e. named "ATLANTIC-B") with costs 200.

     

    When the KCC now checks the replication connections you will have the following connections:

    Server A: <automatically generated> SERVER_B; <automatically generated> SERVER_C

    Server B: <automatically generated> SERVER_A, <automatically generated> SERVER_C

    Server C: <automatically generated> SERVER_A; <automatically generated> SERVER_B

     

    Kind regards,

    M.Hivner

    Montag, 23. Januar 2012 20:03
  • From the current site topology you have hub and spoke tropology and Site C is acting as hub site.Hence the changes made in site A will be replicated  to siteB when siteB replicate with siteC.

    The current site link is created as below

    Site link1:SiteC----SiteA
    Site link2:Site C---SiteB

    Since Site C has low bandwidth( across the Atlantic and connects via a DSL cable connection 15mbps speed) I would recommend to delete the existing site link and create new site link as below.

    Site link1:
    SiteA--SiteB and define the replication schedule and cost as per requiremet.

    Site link2:
    It could be from siteA to SiteC or from SiteB to SiteC depending upon the n/w bandwidth between the sites and define the cost and schedule depending upon the n/w bandwidth and business requirement.

    Once done you need to run repadmin /kcc & repadmin /syncall/AdeP on all DC to generate the required topology.

    Hope this helps

    Regards,
    Sandesh Dubey.
    -------------------------------
    MCSE|MCSA:Messaging|MCTS|MCITP:Enterprise Adminitrator
    My Blog: http://sandeshdubey.wordpress.com
    This posting is provided AS IS with no warranties, and confers no rights.



    • Als Antwort markiert Jim_1235 Sonntag, 18. März 2012 16:41
    Dienstag, 24. Januar 2012 09:14
  • Cheers guys, I'll have a go at that when I get a free moment.

    J.

    Montag, 30. Januar 2012 23:52
  • Just had another look at this, got myself setup with three servers and several firewalls and routers in our test lab.

    Interestingly the initial behaviour mentioned above seemed to replicate itself exactly..when I added the third 2008 R2 server with all the DC's just using the one IPSitelink then the 2008 R2 seem to want to become the hub to the other two sites, so it seems that the intitial behaviour I experienced wasn't random or conceived by different latency or anything, it seems that if you add a 2008 R2 DC site to two exsiting non-R2 2008 sites then the R2 seems to have a higher precedency, which I guess to be honest you'd expect with it being newer technology etc.

    Anyway, now off to experiment with creating new multiple IPsitelinks as suggested above.


    • Bearbeitet Jim_1235 Sonntag, 18. März 2012 16:42
    Samstag, 17. März 2012 11:30
  • OK, that was easy..

    I now have a sitelink for Site A and Site B.

    And a second sitelink for Site A and Site C.

    All seems to be working fine.

    So in effect Site A has now become the hub as opposed to Site C which was the previous unexpected/undesireable behaviour when it was using just the one single default DEFAULTIPSITELINK

    Now what if I want to protect replication between Site B and Site C in the event of Site A being unavailable ?

    Do I just need a third sitelink linking together Site B and Site C set with a different (higher ?) cost ?

    Samstag, 17. März 2012 17:32
  • Great to hear you got what I was trying to say in the previous post.

    Since C was acting as hub and hence there was a delay.Now the topology is correct.

    Yes,you can create Site link from SiteB--SiteC with higher Cost.

    Hope this helps....


    Best Regards,

    Sandesh Dubey.

    MCSE|MCSA:Messaging|MCTS|MCITP:Enterprise Adminitrator | My Blog

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

    • Als Antwort markiert Jim_1235 Sonntag, 18. März 2012 16:41
    Samstag, 17. März 2012 20:45