Questions

One Server, Two Nics, One Pingable

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One Server, Two Nics, One Pingable

Adam S
Please don't ask me exactly how this happened. All I know is that I started messing with bridging network cards. I shouldn't have done it. I'm a bad boy.

The NICS are no longer bridged, but now I can only ping one of the two IP addresses. This screws up DNS and some of my client machines that look for the server by its name can't find it. I suspect this is slowing my network way down too.

The specs are:

Windows 2003 Server

LAN 1 IP: 192.168.1.6
Sub: 255.255.0.0
GW:
DNS: 127.0.0.1

LAN 2 IP: 192.168.1.7
Sub: 255.255.0.0
GW: 192.168.1.1
DNS: 127.0.0.1

Both IPs are set as DNS through DHCP. I can ping LAN2, but not LAN1. What other info should I be looking at or what should I try in order to get the other NIC to work again? Thank you for your time.
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    USIT

    You should have a default gateway added to nic 1. Where are you trying to ping it from?

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    Adam S

    Thank you for your reply. Yes, it is a static IP on both NICs. I can't ping the .6 IP from anywhere on the network, except from the server itself. Giving it a default gateway (192.168.1.1) does not immediately solve the problem. Will it take a while to propogate or should I see results right away?

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    You

    USIT

    sure your not still bridged? To understand the setup better, you have 2 nics for what purpose? Can you pull the .7 cable and see if you can use .6 to get to internet.etc, basically make sure you have a good connection.? I know this may bring down the network, maybe after hours?

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    Adam S

    I'm fairly certain they are not bridged anymore. When they are bridged there is a third network connection that is created. That icon is no longer there and I am able to change the settings of each connection manually.

    It would be interesting to pull the cable on .7. I will wait until after hours, yes. Thank you for your suggestions.

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    robo_dev

    First of all, you do not want to set a GW on the first interface. The problem is you need to turn off automatic metric in the gateway box and assign a lower routing metric to the 1.7 interface. The problem is that DNS has two disjointed routes....IP can only have one default route at a time.

    What happens is DHCP assigns a Gateway to both Nics and dead-gateway-detection kicks in, switching the default gateway to one interface (and blanking out the second one).

    Even worse, if the interface is using DHCP, it won't be pingable by the DHCP server, and other bad things can happen.

    The full answer, I believe is:

    1) assign these two interfaces static IP addresses
    2) assign these with static routing metrics
    3) Turn off routing in the server
    4) use the real IP for DNS, not the loopback
    5) Use NIC teaming, not two nics on same lan

    Can you do 'NIC teaming' on your hardware? that's the right way to do it with 2003. Multiple nics on the same subnet are a recipe for trouble, unless you're using NIC Teaming.

    Also, I think using the loopback DNS address instead of the real DNS also throws dead gateway detection a curve-ball.

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    Adam S

    I'm still reading up on metrics and teaming, but my question is, why can't I ping 192.168.1.6? Doesn't metric just set up priority for IPs with the same physical destination? If I can't ping the IP, then teaming isn't going to help, is it? Thank you very much for your help.

    Edit: I almost forgot, I have an Intel Pro 1000EB type NIC(s). I can't figure out how to run any Intel software to set up teaming, so maybe I can't...?

  • +
    0 Votes
    USIT

    You should have a default gateway added to nic 1. Where are you trying to ping it from?

    +
    0 Votes
    Adam S

    Thank you for your reply. Yes, it is a static IP on both NICs. I can't ping the .6 IP from anywhere on the network, except from the server itself. Giving it a default gateway (192.168.1.1) does not immediately solve the problem. Will it take a while to propogate or should I see results right away?

    +
    0 Votes

    You

    USIT

    sure your not still bridged? To understand the setup better, you have 2 nics for what purpose? Can you pull the .7 cable and see if you can use .6 to get to internet.etc, basically make sure you have a good connection.? I know this may bring down the network, maybe after hours?

    +
    0 Votes
    Adam S

    I'm fairly certain they are not bridged anymore. When they are bridged there is a third network connection that is created. That icon is no longer there and I am able to change the settings of each connection manually.

    It would be interesting to pull the cable on .7. I will wait until after hours, yes. Thank you for your suggestions.

    +
    0 Votes
    robo_dev

    First of all, you do not want to set a GW on the first interface. The problem is you need to turn off automatic metric in the gateway box and assign a lower routing metric to the 1.7 interface. The problem is that DNS has two disjointed routes....IP can only have one default route at a time.

    What happens is DHCP assigns a Gateway to both Nics and dead-gateway-detection kicks in, switching the default gateway to one interface (and blanking out the second one).

    Even worse, if the interface is using DHCP, it won't be pingable by the DHCP server, and other bad things can happen.

    The full answer, I believe is:

    1) assign these two interfaces static IP addresses
    2) assign these with static routing metrics
    3) Turn off routing in the server
    4) use the real IP for DNS, not the loopback
    5) Use NIC teaming, not two nics on same lan

    Can you do 'NIC teaming' on your hardware? that's the right way to do it with 2003. Multiple nics on the same subnet are a recipe for trouble, unless you're using NIC Teaming.

    Also, I think using the loopback DNS address instead of the real DNS also throws dead gateway detection a curve-ball.

    +
    0 Votes
    Adam S

    I'm still reading up on metrics and teaming, but my question is, why can't I ping 192.168.1.6? Doesn't metric just set up priority for IPs with the same physical destination? If I can't ping the IP, then teaming isn't going to help, is it? Thank you very much for your help.

    Edit: I almost forgot, I have an Intel Pro 1000EB type NIC(s). I can't figure out how to run any Intel software to set up teaming, so maybe I can't...?