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Losing Production Network Connection with Dual Nics on different subnets

I have a Systems Center Operations Manger R2 RMS server running Windows Server 2003 x64.  The server is an HP BL460c G1 blade with latest firmware/drivers.  

My network configuration is as follows:
2 Internal Nics
NIC 1: Prod network with 172.17.*.* IP
NIC 2: DISABLED in windows

2 Nics from Mezzanine card
NIC 3: GPRS Modem attached via Network with 192.168.2.1 IP
NIC 4: DISABLED in windows

So in total, I have 4 NICs, 2 of which are in use.  NIC 3 is attached to a cellular modem to perform paging from SCOM.  

The configuration works.  My production network works fine and the paging works fine.  The issue that I have is that after a few days, my production network just stops functioning.  The NIC itself is connected, but I cannot ping the server what-so-ever.  If I connect via the iLO (remote interface) on the server, the server will be up and running.  As soon as I disable NIC 3 with the modem, my production network instantly comes back!

It seems like the production traffic gets confused and no longer tries to go through NIC1.  I can immediatley re-enable NIC3 (modem) and everything works fine again for a few days.  NOTHING is logged in the application or system log stating what happened.  There will eventually be events stating that the server can't communicate with a DC and you can tell when SCOM stops working, but no events state why the traffic stops communicating via NIC1.  

My Binding order is set in the following order:
1. Production Network
2. GPRSModem
3. Disabled NIC
4. Disabled Nic

Note: If I leave the modem NIC disabled, it will function fine and I have not experienced the issue.  

Other note: I completely removed the HP teaming software hoping that it might be it, but that didn't help either.  

Does anyone have a clue why this might be happening?  Please let me know if you need any additional information.  
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ASKER

I think I might have answered my own question, but I'd like someone to confirm.

I just double checked my NIC configuration.  Here is the full config for each active NIC.  I had two different gateways specified!

Production NIC:
IP: 172.17.89.*
Subnet: 255.255.255.0
Gateway: 172.17.89.1

Modem NIC:
IP 192.168.2.1
Subnet: 255.255.255.0
Default Gateway: 192.168.2.1

I just cleared the default gateway on the modem NIC and I can still communicate with it just fine.  Could that have been the issue?  
STEHelp,

It shouldn't be an issue, but it can be an issue.  While I am sure you would do this anyway, your best bet a this time is to monitor the machine now that you have made this change and see what happens.

Justin
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magicdlf

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That makes sense.  I will close this for now and monitor.