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Unable to ping NLB cluster ip.

Beantwortet Unable to ping NLB cluster ip.

  • Thursday, June 14, 2012 9:19 PM
     
     
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    We had two sharepoint 2007 WFEs in one subnet. They are load balanced via win NLB and its just a two node cluster. We have to move these servers from one subnet to another subnet. The idea is to move one server first to other subnet,create an NLB cluster and make this server part of it and direct traffic to it. Then move the second server and add it to this cluster. When we created the cluster with that one server in the other subnet, we were not able to ping the cluster ip from the server in the other subnet. We were able to ping it from the same subnet server. We are using windows server 2003, unicast mode for NLB and the servers have to NICs - one for internet traffic(which we were able to ping from outside the subnet) and the other for nlb(which we were not able to ping once nlb is configured). Any suggestions?
     

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  • Friday, June 15, 2012 9:46 AM
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    Hi,

    You can not use the same NLB cluster name. Create a new name for the new cluster.

    So are you pinging the NLB cluster NetBIOS name , so if you can ping the server on the same subnet as the new NLB clusternetbiosname than the NLB is working.

    You need to talk to your network admin about routing to the other subnet, and check your firewall most issues are about not configuring the FW.

      

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  • Tuesday, June 19, 2012 3:22 AM
     
     
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    Looking back all the post.. is interesting to see this forum have grow

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  • Wednesday, June 20, 2012 5:26 AM
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    Hi shazinus,

    Thanks for posting here.

    >. When we created the cluster with that one server in the other subnet, we were not able to ping the cluster ip from the server in the other subnet. We were able to ping it from the same subnet server.

    It seems this router that connects both subnets didn’t been properly configured to accept proxy ARP responses. Could we double check that first ?

    There is no response when you use ping to access the cluster's IP address from an outside network.

    Verify that you can use ping to access the dedicated IP addresses for the cluster hosts from a computer outside the router. If this test fails, and you are using multiple network adapters, the issue is not related to NLB. If you are using a single network adapter for the dedicated and cluster IP addresses, consider the following causes:

    • Cause: If you are using multicast support, you might find that your router has difficulty resolving the primary IP address into a multicast media access control (MAC) address by using the Address Resolution Protocol (ARP).
    • Solution: Verify that you can use ping to access the cluster from a client on the cluster's subnet and to access the cluster hosts' dedicated IP addresses from a computer outside the router. If these tests work properly, the router is probably at fault. You should be able to add a static ARP entry to the router to circumvent the issue. You can also turn off NLB multicast support and use a unicast network address without a hub.
    • Cause: When using NLB in multicast or unicast mode, routers need to accept proxy ARP responses (IP-to-network address mappings that are received with a different network source address in the Ethernet frame).
    • Solution: Make sure that your router has proxy ARP support turned on. You can also set a static ARP entry to keep proxy ARP support disabled in the router.
    • Cause: Internet control message protocol (ICMP) to the cluster is blocked by a router or firewall.
    • Solution: Allow ICMP traffic through the router or firewall. Be aware that this may expose your system to additional security risk.

    Thanks.

    Tiger Li

    Tiger Li

    TechNet Community Support

     
  • Monday, August 13, 2012 4:10 PM
     
     
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    Hi guys,

    I have a strange problem, I have 2 CAS server on wich the NLB is been configured.  all the IP's are on the same subnet.

    The Ip of second node on the NLB stops pinging for 20 min and comes up again (but this will ping from all the other place)

    any idea why this is happening..

    NLB on unicast mode, layer 3 switch.



    • Edited by D-Raj Monday, August 13, 2012 4:11 PM
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  • Thursday, September 20, 2012 6:24 PM
     
     
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    Hi guys,

    I have a strange problem, I have 2 CAS server on wich the NLB is been configured.  all the IP's are on the same subnet.

    The Ip of second node on the NLB stops pinging for 20 min and comes up again (but this will ping from all the other place)

    any idea why this is happening..

    NLB on unicast mode, layer 3 switch.




    I found the cause, the exchange runs on VM and NLB is on unicast, hence while taking snapshot or making any vmotion the nlb will expose the actual IP of the machine and thats when the ping problem starts.

    Regards D-Raj