Windows 2000 server as Network Router

Discussion in 'Server Networking' started by xisnet, Jun 16, 2005.

  1. xisnet

    xisnet Guest

    Hi All,

    I have a server with 2 NICs, I already configured RRAS to make my server as
    network router. Below the configuration has been done.

    Ethernet 1 (connect to Subnet A)
    IP Address :
    Subnet Mask :
    Gateway :

    Ethernet 2 (connect to Subnet B)
    IP Address :
    Subnet Mask :

    Now from subnet A I can ping the computer at Subnet B. But I can't ping the
    computer in Subnet A from Subnet B. The following my Static IP Route Table:

    Interface List
    0x1 ........................... MS TCP Loopback interface
    0x1000003 ...00 00 4c 9f 03 3c ...... Intel(R) PRO/1000 Adapter
    0x1000004 ...00 00 4c 9f 03 3b ...... Intel 8255x-based Integrated Fast Ether

    Active Routes:
    Network Destination Netmask Gateway Interface Metric 1 1 1 1 1 1 1 1 1 1 1
    Default Gateway:
    Persistent Routes:

    xisnet, Jun 16, 2005
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  2. There are no "static routes" and the routing table should never be touched o
    altered. this is an extremely simplified situation with two networks with a
    LAN Router between them. The Router is already "aware" of both networks
    because both are directly connected to it, so there are no static routes to

    All machines on the LAN must use the LAN Router as their Default Gateway,
    however they must use the Inerface that faces them (is in their own subnet).

    If the Internet is invloved and you have a typical NAT Device on the network
    Edge, then the LAN Router must use this NAT Device as its Default
    Gateway,...while all Client use the LAN Router as their Default Gateway.

    Now if A can ping B, than the Router is fine both in directions because
    "ping" from any direction requires that things work both ways (the reply has
    to get back to the sender). If B cannot ping A you may have a personal
    firewall running on the machine in A that stops it from recieving the ping.
    Phillip Windell, Jun 16, 2005
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  3. xisnet

    Bill Grant Guest

    This is a common question and I would add this to Phillip's expanation.
    It really just says the same things in a different way.

    When you enable IP routing it will forward traffic between the
    interfaces. But it can only forward traffic which actually gets to the
    router! Making changes at the router itself cannot fix this. You need to
    make changes elsewhere in the network to get the traffic to the router.

    In the simplest case of one router, it works fine. One each client you
    set the default gateway to be the local router NIC. Traffic in the local
    subnet is delivered directly (ie "on the wire" using hardware addressing).
    Traffic for the "other" subnet is sent to the router. It can deliver the
    traffic directly because it has an interface in the other subnet. The setup
    for this is simple.

    192.168.11.x dg
    | dg blank
    router dg blank
    192.168.21.x dg

    If one of these subnets has another router, this usually fails. It fails
    because the clients are set to use the "other" router as their default
    gateway (to contact another site or the Internet). Traffic for the second
    local subnet now goes to the external router and is lost. To solve the
    problem you need extra routing to get the local traffic to the internal

    You can do this by adding a static route to every client to send traffic
    for the other local subnet to the internal router. This will override the
    default route, and get the local routing working. A simpler approach is to
    add the extra route to the external router. The traffic for the local subnet
    will then be redirected (or "bounced") to the internal router. A typical
    setup for this would look like

    External network
    external router
    192.168.11.x dg
    | dg
    internal router dg blank
    192.168.21.x dg

    If you add the extra routing to the external router eg

    the local subnets will be able to route correctly. In addition, the
    clients on the internal subnet ( will also be able to see the
    external network. Traffic will go out by default routing and get back
    because of the route you added to the external router (to forward traffic
    for to the internal router).
    Bill Grant, Jun 18, 2005
  4. xisnet

    xisnet Guest

    Thanks for the answer, Now after I checked the personal firewall I can ping
    to windows XP but I still cannot ping windows NT or windows 98, from what I
    know either of this OS don't have personal firewall. So is there any setting
    I need to check again.


    xisnet, Jun 20, 2005
  5. xisnet

    xisnet Guest

    Thank Phillips and Bill, I already solved the problem.

    Thank You.
    xisnet, Jun 20, 2005
  6. xisnet

    xisnet Guest


    Now both network can ping each other and access each other, but one subnet
    that not same which subnet which email & proxy server reside have a problem
    browse an internet and access to email server. Below my network structure

    External router(
    Email & Proxy server ( dg
    Client ( dg
    | Subnet A dg blank
    internal router dg blank
    | Suhnet B
    Client( dg -> can't access internet and email

    What I need to set for Subent B can access to the internet and Email

    xisnet, Jun 20, 2005
  7. xisnet

    Bill Grant Guest

    First up, you need a static route on the email/proxy server to forward
    traffic for machines to At the moment this
    traffic will be going to the default router at and getting

    As Phillip said earlier, you also need to define the subnet
    as being part of your internal network (ie included in the LAT) in the proxy
    server settings.
    Bill Grant, Jun 20, 2005
  8. I wouldn't add static routes to the clients. I would add the routes to the
    Router they are already using as the DG. This way the routing is
    centralized. Then future changes would be made on a single device instead of
    repeated changes on every client. Both methods work, but centralizing it is
    more managable, especially if he system becomes large. In the diagram
    below, the furthest network opposite of router#2 is a Stub network
    (192.168.200.x), so no Static Route is need on router#2,..the DG on route#2
    covers it.

    Internet NAT Device =
    All Clients in 192.168.11.x use DG-
    All Clients in 192.168.21.x use DG-
    All Clients in 192.168.200.x use DG-
    No Statics Routes on clients

    Internal router #1
    <statics routes added here>
    [net] [mask] [gateway] [int]
    [metric] mask- int#2 metric 1

    Internal router#2
    Phillip Windell, Jun 20, 2005
  9. Forgot the Static route on the NAT Device. It will need that to see the
    other two LAN segments. It can be done with a single route using a 16bit

    Internet NAT Device =
    [net] [mask] [gtwy] [metric] mask- metric 1
    Phillip Windell, Jun 20, 2005
  10. xisnet

    xisnet Guest


    My external router is physical router which is connected to leased line.
    Then my email server and proxy server is Linux server which reside in Subnet
    A and my physical router also reside in subnet A. The computer in Subnet A
    dont have any problem at all. The problem only happened to Subnet B they can
    access another pc and printer in Subnet A but cannot access and email & proxy
    server in Subnet A.

    Thank for help,
    xisnet, Jun 21, 2005
  11. xisnet

    Bill Grant Guest

    Since you are using a proxy server to access the Internet, the clients
    in subnet A don't need to know about the Internet router. So your setup with
    the clients having their default gateway set to the internal router should
    give you routing between clients.

    You can't use this method for the proxy/mail server because it does need
    to know about the Internet router. So it has to use the Internet router as
    its default gateway. For this machine to route to the machines in subnet B,
    it must have a static route to send traffic for subnet B to the internal
    Bill Grant, Jun 21, 2005
  12. Bill's got you covered, just follow what he is saying. There's no point in
    me reapting what he is saying. I only wanted to add a little different
    routing method that I prefer,...other than that it is the same thing.


    Phillip Windell [MCP, MVP, CCNA]

    Phillip Windell, Jun 21, 2005
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