Windows 2003 server loses 'default gateway'

Discussion in 'Server Networking' started by Blake, May 20, 2005.

  1. Blake

    Blake Guest

    We have a Windows 2003 machine that was an in-place upgrade of Windows 2000
    server. This machine also runs Oracle. Twice in the past week this machine
    has dropped network connectivity - running 'ipconfig' shows that it has no
    'default gateway' entry, so it can't communicate beyond its subnet.

    A reboot clears the problem, but I fear it will return. Has anyone seen
    this behavior?

    Thanks
    Blake
     
    Blake, May 20, 2005
    #1
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  2. Is your server configured to obtain IP configuration from DHCP? You might
    want to configure your server with static IP address and hardcode the rest
    of parameters such as default gateway as well.
     
    Arek Iskra [MVP], May 21, 2005
    #2
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  3. Blake

    ChipDancer Guest

    I am having the exact same problem here!

    The server (windows 2003 standard) ran fine for over a year, then suddenly
    the public connection just started dropping the default gateway. At first we
    thought it was something corrupt in the OS and had to keep rebooting the
    server once of twice a day so we tore the system down and rebuilt it from
    scratch.

    But the problem remained, so we assumed it might be a faulty NIC and we
    replaced that as well and the problem remained.

    I found out that instead of rebooting I could just go into network
    properties for the connection and hit the repair option and that would fix
    the connection, but this is rediculous!

    INFO: Two seperate NICS. One for the internal network configured with a
    different gateway and IP range to match the internal network; is a static IP
    and DNS and has never had a problem.

    Second NIC is also static with configured IP and DNS on a seperate gateway
    that we use for public access, specifically FTP on this system. It always
    loses it's default gateway within a day, sometimes twice!

    Please note that our domain server, SBS 2003 Pro uses the same public config
    as the problem server and suffers no such problems (different IP though).

    Please help! I'm at my wits end and am starting to believe that perhaps
    something that MS included in one of it's patches is the cause of this.

    Thanks in advance,

    ChipDancer
     
    ChipDancer, May 23, 2005
    #3
  4. Blake

    Blake Guest

    ChipDancer,
    You are on to something. My server has 2 NICs also - one on our
    standard subnet and one on a private network. I think it had something to
    do with that TCP/IP patch that was issued last month. That is basically
    when this started.

    Blake
     
    Blake, May 23, 2005
    #4
  5. Blake

    Blake Guest

    Arek,
    Thanks, but this is a static IP machine. No DCHP involved.

    Blake
     
    Blake, May 23, 2005
    #5
  6. Blake

    ChipDancer Guest

    Exactly my thoughts!!!

    I bet if I take the server down and rebuild it without anything but SP2 it'd
    work fine!, but since the server is a production system in use MS needs to
    verify this issue and resolve it ASAP!

    ChipDancer.
     
    ChipDancer, May 23, 2005
    #6
  7. Blake

    Bill Grant Guest

    Why do you have a default gateway set on your private side NIC? A
    machine can only have one default gateway and one default route (not one per
    interface!) Only one default route can be active at any time.

    What exactly do you think the default gateway setting on the internal
    NIC does for you?
     
    Bill Grant, May 24, 2005
    #7
  8. Blake

    ChipDancer Guest

    I think there was a misunderstanding. The Gate way is being dropped on the
    public side connection. One NIC handles the public side of traffic, the other
    NIC handles the internal network traffic. Both use completely different
    static IP schemes and different gateways.

    The system is not a domain or DHCP server, just a production use FTP server.

    The system ran fine in it's current configuration for more then six months,
    almost a year, before is started just dropping the gateway on the public side
    around a month ago, the same time that other people started having the same
    thing happen to them with Server 2003 Standard.

    I would like an MS Rep to comment on this since it's happened to multiple
    people and verify if this is the result of one of their recent patches.

    ChipDancer
     
    ChipDancer, May 24, 2005
    #8
  9. Blake

    Blake Guest

    ??

    You can certainly have multiple gateways on a single multi-homed machine.
    The whole purpose of having 2 NICs is so the machine can live on 2 separate
    subnets. I have a machine that has 2 NICs on 2 subnets and I use a static
    ROUTE command to tell that machine where to send certain packets.

    And as ChipDancer pointed out it is the 'public' gateway that is
    disappearing, not the 'private' one.

    Blake
     
    Blake, May 24, 2005
    #9
  10. You can't have two Default Gateways.

    One Nic uses one,..the other must be left *blank*!

    --

    Phillip Windell [MCP, MVP, CCNA]
    www.wandtv.com
     
    Phillip Windell, May 24, 2005
    #10
  11. You don't understand. You can't have two Default Gateways,...period. The
    fact the the other Nic has one is why you get the irratic behavor. only one
    Nic can have a Default Gateway,...the other must be left blank.
     
    Phillip Windell, May 24, 2005
    #11
  12. Multiple *Default* gateways are not allowed.
    Adding a gateway with a static route is not a *Default* gateway.

    Default Gateways use "0.0.0.0" as the destination.
    Gateways with static routes use specific networks as the destination.

    We're are not making this stuff up ;-)

    157025 - Default Gateway Configuration for Multihomed Computers
    http://support.microsoft.com/default.aspx?scid=kb;en-us;157025&Product=win2000

    Default gateways
    http://www.microsoft.com/technet/pr...elp/6c7c7ab2-cfdc-4dfe-8560-570d3859f5b1.mspx

    Default Gateway Behavior for Windows TCP/IP
    http://www.microsoft.com/technet/community/columns/cableguy/cg0903.mspx

    159168 - Multiple Default Gateways Can Cause Connectivity Problems
    http://support.microsoft.com/kb/159168/EN-US/
     
    Phillip Windell, May 24, 2005
    #12
  13. Blake

    ChipDancer Guest

    Hi Philip and thanks for the quick bit, but the confusion is that both IP
    schemes have unique gateways specific to the individual networks they are on.
    People seem to be jumping the gun here and not really reading through all the
    posts.

    Two NICs, one for the private internal network, and one for the public
    secure FTP. Both use static assigned IP schemes on their own gateways. It
    worked until 4-5 weeks ago for almost a year since the server was built. Our
    domain server, SBS 2003 Pro is set up identically and still works with no
    problem.

    Any questions?

    ChipDancer
     
    ChipDancer, May 24, 2005
    #13
  14. Ok, but could we clarify, so we don't chase our tails? Could you paste the
    output of "IPConfig /all" of the involved machine(s) into a post?

    There is a distinction between a Gateway and a Default Gateway. The Default
    Gatway is entered within the normal GUI of the the Nic's TCP/IP Config and
    appears in the Route Table as "0.0.0.0". A Gateway is entered directly into
    the Routing Table via commandline or via RRAS.

    It is not unusual for a machine with improper multiple Default Gateways to
    work fine for a period of time before it starts to give trouble. It would
    also not be unusual for MS's "patches" somewhere along the way to cause
    problems with an improperly config'ed machine that may have seemingly work
    fine earlier.
     
    Phillip Windell, May 24, 2005
    #14
  15. Blake

    ChipDancer Guest

    Here is the IPCONFIG Info:

    C:\Documents and Settings\administrator.TKG>ipconfig /all

    Windows IP Configuration

    Host Name . . . . . . . . . . . . : appsvr
    Primary Dns Suffix . . . . . . . : TKG.local
    Node Type . . . . . . . . . . . . : Unknown
    IP Routing Enabled. . . . . . . . : No
    WINS Proxy Enabled. . . . . . . . : No
    DNS Suffix Search List. . . . . . : TKG.local

    Ethernet adapter Public:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Realtek RTL8139 Family PCI Fast
    Ethernet
    NIC
    Physical Address. . . . . . . . . : 00-0D-88-3D-C9-37
    DHCP Enabled. . . . . . . . . . . : No
    IP Address. . . . . . . . . . . . : 192.168.168.13
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.168.1
    DNS Servers . . . . . . . . . . . : 64.105.199.74
    64.105.159.250

    Ethernet adapter Internal:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Intel(R) PRO/100+ Server Adapter
    (PILA847
    0B)
    Physical Address. . . . . . . . . : 00-30-48-23-9F-A1
    DHCP Enabled. . . . . . . . . . . : No
    IP Address. . . . . . . . . . . . : 192.168.31.15
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.31.2
    DNS Servers . . . . . . . . . . . : 192.168.31.2

    C:\Documents and Settings\administrator.TKG>

    PS: The reason why I kept calling it the default gateway is because of the
    way it was listed above.


    ChipDancer



    *****************************************************


     
    ChipDancer, May 24, 2005
    #15
  16. Blake

    Blake Guest

    Phillip,
    The following article from M$ TechNet uses the term 'multiple default
    gateways' here - and like ChipDancer said that is what the screen says.

    http://www.microsoft.com/technet/community/columns/cableguy/cg0903.mspx

    I don't wish to argue the point regarding terminology. The server works
    fine for a while, then stops. I can ping hosts on the local subnet, but no
    other. When I run 'ipconfig /all' I get the proper information but the
    'default gateway' is blank. A reboot fixes the problem.

    This server has run fine in this configuration for 2 years. Only since the
    patches from last month has the problem occurred - and I have had numerous
    problems with the TCP/IP patch that was released.

    Blake


     
    Blake, May 24, 2005
    #16
  17. Blake

    Bill Grant Guest

    Have you actually read and understood what the Cable Guy article says
    about multiple gateways?

    A default gateway specifies where traffic will go if no specific route
    exists. For that reason, a machine can only use one of them. If more than
    one is specified, one is selected by the system and the other(s) used only
    if that one fails. (See the section in the article on dead gateway
    detection). The normal situation is to use default routing for non-specific
    routing (such as to the Internet) and specific routing (such as static
    routes) to override the default for known IP ranges (such as local subnets).

    The standard advice is as Phillip put it. It is safest to only specify
    one default gateway on one interface. If you specify more than one, the
    machine decides which one to use based on a heap of criteria, and it won't
    necessarily do what you want or expect. In particular, RRAS Internet routers
    do not like default gateway settings on the private NIC, and will usually
    refuse to route to the Internet if one exists.

    The fact that your setup worked in the past doesn't mean it was right!
    Many setups which worked in the past fell over with SP1 (just as many also
    fell over with SP2 for XP).

    I can only repeat my question. What do you think the default gateway
    setting on the 192.168.168 NIC is doing for you? What fails if you remove
    it? With that information we can see what static routing is required to
    make your router work with one default gateway set on one interface.
     
    Bill Grant, May 25, 2005
    #17
  18. Blake

    Blake Guest

    I have removed the 'default gateway' entry on the 'private' NIC simply
    because I don't need it - that NIC is cabled directly to a piece of
    networking equipment using a private IP on the same 196.168 subnet.

    I will update the thread as things improve/don't.

    Thanks.

    Blake

     
    Blake, May 25, 2005
    #18
  19. That is the Default Gatewway you see listed there.
    It is incorrectly configured.
    One of those must be left blank. A Default Gateway is the "bit bucket" for
    "unknown routes". It is not possible to have two "default routes" to two
    "unknown somewheres". There can only be, by definition, only one "unknown
    somewhere",...therefore there can only be one Default Gateway. It is the
    way TCP/IP works,...it in not a "Windows thing" or an "MS thing".

    If you have noticed,...Server2003 warns you about this when you attempt to
    enter a Default Gateway when another Nic already has one. Hopefully in the
    future MS will re-design the GUI so that once one Nic has a Default Gateway,
    the same slot on the other Nics will be greyed-out and not let you enter
    one. But for now, it still lets you add them (in spite of the warning)
    even though you are not supposed to.

    --

    Phillip Windell [MCP, MVP, CCNA]
    www.wandtv.com


     
    Phillip Windell, May 25, 2005
    #19
  20. I never heard of M$. I find it annoying and insulting,...perhaps you meant
    MS or perhaps $un Micro$y$tem$?

    There is a big difference between a multiple Default Gateways on the same
    Nic ,...and having a single Default Gateway on multiple Nics.

    Multiple Gateways on the same Nic is for Dead Gateway Detection,...that
    works. Using a Default Gateway on each Nic is the problem. The D-G-D
    process will still act upon it but the results are undesireable and
    unpredictable.

    Here's a few quotes from the article you mentioned:

    "The combination of multiple configured default gateways pointing to
    disjoint networks and dead gateway detection can cause confusing
    consequences. If you configure default gateways for both Internet and
    intranet interfaces, the result can be intermittent connectivity to the
    Internet or your intranet when dead gateway detection changes the active
    default gateway. For example, when the active default gateway points to the
    Internet and dead gateway detection switches the active default gateway to
    the intranet default gateway, DNS-based name resolution for Internet names
    and Internet-based connections can fail."

    ....and also...

    "Because the TCP/IP protocol only uses a single default route in the routing
    table at any one time for default route traffic, default gateways configured
    on multiple interfaces that are connected to disjoint networks can produce
    undesirable results."

    .....and also...

    "Do not configure a default gateway on any other interface. Instead use
    static routes or dynamic routing protocols to add the routes that summarize
    the addresses of the other disjoint networks to the local IP routing table."
     
    Phillip Windell, May 25, 2005
    #20
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