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One Server, Two Nics, One Pingable

By 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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All Answers

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Static ip?

by USIT In reply to One Server, Two Nics, One ...

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

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Static IP, pinged from anywhere on the network

by Adam S In reply to Static ip?

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

by USIT In reply to Static IP, pinged from an ...

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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Not Bridged

by Adam S In reply to You

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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Routing metric, dead gateway detection

by robo_dev In reply to One Server, Two Nics, One ...

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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But does metric affect pinging?

by Adam S In reply to Routing metric, dead gate ...

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...?

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