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We have 3 Dell PowerEdge 2950 Servers.

2 x 3.2GHz 5060 Dual Core 16GB RAM 6x146GB

Recently, one of the servers experienced a NIC failure so we decided to replace all the NICs on all three servers with Broadcom's NetXtreme II 1 Gigabit NICs (we use DHCP).

Then something strange started to occur. Sometimes when these servers are power cycled (we are in the process of moving our servers to a different location) all of them would become unreachable (all together). Interestingly when they are just rebooted, they would still be reachable.

So, when they became unreachable, I noticed that running ifconfig -a showed all the NICs on the servers but the status message would show:

eth0  Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx  
      BROADCAST MULTICAST  MTU:1500  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
      Interrupt:16 Memory:xxxxx-xxxxx

whereas when they are all reachable the status message would show:

eth0  Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx  
      inet addr:10.0.0.xx  Bcast:10.0.0.xx  Mask:255.255.255.0
      inet6 addr: xx::xx:xx:xx:xx/xx Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:466475604 errors:0 dropped:0 overruns:0 frame:0
      TX packets:403172654 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:2574778386 (2.5 GB)  TX bytes:1618367329 (1.6 GB)
      Interrupt:16 Memory:xxxxx-xxxxx

To make the servers reachable again, I would have to take down the NICs and bring them back up using the ifconfig command.

My question is why is this needed? I never had to do this when we had our old NICs before. I checked all the OS logs to see if there was any problem with the NIC or something else might not be working correctly but didn't find any unusual stuff there.

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1  
Can you provide more information about your Operating System, if NetworkManager controls the networking, how your network configuration file looks like? –  val0x00ff Jan 22 '13 at 13:39
    
We're not using NetworkManager or anything special. The servers are used as DB servers that our custom application connects to via host name and their IP addresses are assigned automatically by our DHCP server. They are pretty much vanilla Ubuntu + MySQL. We've never messed around with any OS settings or anything like that. –  Edenbauer Jan 22 '13 at 22:29
    
How does your /etc/network/interfaces file look like. Have you there iface eth0 inet dhcp or is there any other line in the file? Does the interface come up when you restart networking e.g service networking restart ? also check service network-manager status and see its status. –  val0x00ff Jan 23 '13 at 8:46

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