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2 NICs response issue

    Question

  • Hi,

    Windows Server 2003 multi homed server. There are 2 NICs and both are on different subnet. When a request is answered by the server, it uses the second NIC to respond back instead of the NIC which received the request. Only first NIC has the default gateway configured. Even if we add a host based routing to the destination using the first NIC the behaviour remains the same. I remember that there is a registry key to fix this behaviour. But forgot now. Please help.


    Thanks, MPC

    Thursday, April 12, 2012 11:53 AM

Answers

All replies

  • I dont know of a registry fix, but it sounds like routing is the issue.  The data comes in one NIC, when the server responds, there is not a route back to the other network except through the default gateway which is defined on the other NIC.  Have you tried adding a static route for the receiving NIC to the network in question?
    Thursday, April 12, 2012 12:12 PM
  • Yes. Both host based routing and network based routing never helped. It isn't using the NIC with default gateway set.

    Thanks, MPC

    Thursday, April 12, 2012 1:16 PM
  • Give some more specifics.  Connection is made with which NIC( With or without the default gateway)?  Server responds with which NIC (With or without the default gateway)?

    Can you give the IP of the source address and paste a copy of your routing tables here?

    Thanks

    • Proposed as answer by Tiger Li Wednesday, April 18, 2012 2:38 AM
    • Marked as answer by Tiger Li Thursday, April 19, 2012 10:15 AM
    Thursday, April 12, 2012 1:22 PM
  • Hi,

    Thanks for posting here.

     

    Yes, please first show us the information that Russ asked .Meanwhile, could we check the interfaces binding order on this server ?

    How to change the binding order of network adapters in Windows XP and in Windows 2000

    http://support.microsoft.com/kb/894564/

    A blog post may also help to get better understanding on its mechanism:

    Source IP address selection on a Multi-Homed Windows Computer

    http://blogs.technet.com/b/networking/archive/2009/04/24/source-ip-address-selection-on-a-multi-homed-windows-computer.aspx

    Thanks.

    Tiger Li


    Tiger Li

    TechNet Community Support

    • Proposed as answer by Tiger Li Wednesday, April 18, 2012 2:38 AM
    • Marked as answer by Tiger Li Thursday, April 19, 2012 10:15 AM
    Friday, April 13, 2012 7:10 AM