Allow two subnets to talk

Discussion in 'Server Networking' started by Dan Reber, Sep 19, 2005.

  1. Dan Reber

    Dan Reber Guest

    I have a network with two subnets being used with a windows 2003 Ent as a
    PDC. Since the PDC has two NIC cards both subnets can log into the domain
    without a problem. The issue is that PCs from different subnets
    (255.255.255.248 & 255.255.255.0) cannot "talk" with each other. What do I
    need to do to get them to see each other when they browse the network?

    Thanks

    Dan
     
    Dan Reber, Sep 19, 2005
    #1
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  2. Have you configured the RRAS?
    Anyway I suggest to not use double NIC on DC........
    --
     
    Giuseppe Nacci, Sep 19, 2005
    #2
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  3. The DC should run with only one Nic and exist on only one subnet (doesn't
    matter which one). A LAN Router should be placed between the Subnets. SBS
    being the exception, there are a lot of potential networking issues that
    arise from multi-homing a DC.

    Here are some examples.

    272294 - Active Directory Communication Fails on Multihomed Domain
    Controllers
    http://support.microsoft.com/default.aspx?scid=kb;en-us;272294

    191611 - Symptoms of Multihomed Browsers
    http://support.microsoft.com/default.aspx?scid=kb;EN-US;191611

    It doesn't mean it can't be done (it is done with SBS), but it can just be
    troublesome and is recommended that you avoid that situation.

    --
    Phillip Windell [MCP, MVP, CCNA]
    www.wandtv.com
    -----------------------------------------------------
    Understanding the ISA 2004 Access Rule Processing
    http://www.isaserver.org/articles/ISA2004_AccessRules.html

    Microsoft Internet Security & Acceleration Server: Guidance
    http://www.microsoft.com/isaserver/techinfo/Guidance/2004.asp
    http://www.microsoft.com/isaserver/techinfo/Guidance/2000.asp

    Microsoft Internet Security & Acceleration Server: Partners
    http://www.microsoft.com/isaserver/partners/default.asp
     
    Phillip Windell, Sep 19, 2005
    #3
  4. Dan Reber

    Dan Reber Guest

    I installed it on the server but I am not sure how to configure it.
     
    Dan Reber, Sep 19, 2005
    #4
  5. This is not required, DC can have network interfaces in as many subnets as
    needed, and act as a router at the same time.

    All the issues with multihomed DCs are related to network browsing, i.e. to
    building the computer list in "My Network Places" - which is absolutely not
    required (and, in my opinion, even MUST be avoided in corporate
    environments) and does not affect users' ability to access network resources
    in any way.

    --
    Dmitry Korolyov []
    MVP: Windows Server - Directory Services


     
    Dmitry Korolyov [MVP], Sep 20, 2005
    #5
  6. OK, here's an example:

    NIC 1, ip: 192.168.0.1, attached to subnet 192.168.0.0/24
    NIC 2, ip: 192.168.1.1, attached to subnet 192.168.1.0/24

    In this case you configure 2 static routes in RRAS:

    1) route to 192.168.0.0/24, through interface NIC 1
    2) route to 192.168.1.0/24, through interface NIC 2

    This way clients from the same network as NIC 1 will be able to access other
    network segment (related to 192.168.1.0/24) through this router, but:
    1. They must have configured with 192.168.0.1 as the default gateway (or
    some other gateway that also has the route to 192.168.1.0/24 subnet)
    2. The clients in the other subnet (where NIC 2 is) should use 192.168.1.1
    as the gateway (or, similary, some other gateway that also has the route to
    192.168.0.0/24 subnet)
     
    Dmitry Korolyov [MVP], Sep 20, 2005
    #6
  7. Dan Reber

    Dan Reber Guest

    Thanks, I will look into this but I have a question first. The IPs for the
    255.255.255.248 subnet are 70.x.x.65 thru 70.x.x.69 and the IPs for the
    255.255.255.0 subnet are 192.168.0.1 thru 192.168.0.50. Can these still
    talk to each other?

    Thanks

    Dan


     
    Dan Reber, Sep 20, 2005
    #7
  8. Dan Reber

    Dan Reber Guest

    I want to test but I am not sure what the different settings are (I am a
    programmer and networking is not my forte). WhI click "New Statis Route..."
    the dialog box asks for:

    Interface: This is the NIC I assume.
    Destination: Not sure what to put here.
    Network mask: Not sure what to put here.
    Gateway: Not sure what to put here.
    Metric: Not sure what to put here.

    Thanks for you help.

    Dan


     
    Dan Reber, Sep 20, 2005
    #8
  9. Dan Reber

    Todd J Heron Guest

    Problem with that is a mutlihomed DC will register SRV records for every
    interface in DNS, complicating the environment. A myriad of troubleshooting
    issues often arise as a result of this, such as clients trying to reach DC
    on IP interface to which it has no route. I've seen some of this in the
    field.

    --
    Todd J Heron, MCSE
    Windows Server 2003/2000/NT; CCA
    ----------------------------------------------------------------------------
    This posting is provided "as is" with no warranties and confers no rights

    This is not required, DC can have network interfaces in as many subnets as
    needed, and act as a router at the same time.

    All the issues with multihomed DCs are related to network browsing, i.e. to
    building the computer list in "My Network Places" - which is absolutely not
    required (and, in my opinion, even MUST be avoided in corporate
    environments) and does not affect users' ability to access network resources
    in any way.

    --
    Dmitry Korolyov []
    MVP: Windows Server - Directory Services


     
    Todd J Heron, Sep 20, 2005
    #9
  10. Dan Reber

    Bill Grant Guest

    I aggree with that, Todd. If you are using DDNS you get the same sorts
    of name resolution problems with multihomed DCs (and remote access servers
    which become multihomed as soon as anyone connects) as you used to get with
    Netbios names. As with Netbios there are workarounds, but it is easier to
    avoid them in the first place if you can.
     
    Bill Grant, Sep 21, 2005
    #10
  11. Well, technically yes, BUT one of these subnets is from a private ip range
    (192.168.0.0 - 192.168.255.255). Are you sure that you are using public
    addressing for one office and private for another? I am asking because
    usually you would set up NAT, not direct routing, between private and public
    networks.

    --
    Dmitry Korolyov []
    MVP: Windows Server - Directory Services


     
    Dmitry Korolyov [MVP], Sep 21, 2005
    #11
  12. Destination: The network address for the destination network, for example,
    192.168.1.0
    Network mask: pretty descriptive, the appropriate network mask, for our
    example - 255.255.255.0
    Gateway - the ip address of another router
    Metric - may leave the default value 1.

    --
    Dmitry Korolyov []
    MVP: Windows Server - Directory Services


     
    Dmitry Korolyov [MVP], Sep 21, 2005
    #12
  13. Well, technically this isn't much of a problem, because SRV records have
    hostname, not ip, registered, and when resolving the hostname to ip, netmask
    ordering feature will help the client to get the correct ip - which most
    likely will be reachable from the client's interface.

    But generally I agree, less problems, even possible problems, is always
    better.

    --
    Dmitry Korolyov []
    MVP: Windows Server - Directory Services


     
    Dmitry Korolyov [MVP], Sep 21, 2005
    #13
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