Link goes up and down constantly

Hello everyone,

I've been having a problem with ASG 7.511 where basically one of my NICs constatnly goes up and down erratically.

Network interfaces are as follows:

eth0 - LAN
eth1 - WAN
eth2 - LAN (hostile/dangerous)
eth3 - DMZ

All the interfaces are the same type of NIC except eth1. The ASG dashboard indicates that all the NICs have a 'State' of 'Up' but eth2's 'Link' is 'Down'. If I attempt to plug in a switch to eth2, it will oscillate between up and down, indefinitely. Kernel messages from the last time I tried this are as follows:

Code:

...

2012:02:07-13:47:39 fw kernel: r8169: eth2: link up

2012:02:07-13:47:43 fw kernel: r8169: eth2: link down

2012:02:07-13:48:08 fw kernel: r8169: eth2: link up

2012:02:07-13:51:01 fw kernel: r8169: eth2: link down

2012:02:07-13:51:04 fw kernel: r8169: eth2: link up

2012:02:07-13:51:16 fw kernel: r8169: eth2: link down

2012:02:07-13:51:20 fw kernel: r8169: eth2: link up

2012:02:07-13:52:12 fw kernel: r8169: eth2: link down

2012:02:07-13:52:17 fw kernel: r8169: eth2: link up

2012:02:07-13:52:22 fw kernel: r8169: eth2: link down

2012:02:07-13:54:15 fw kernel: r8169: eth2: link up

2012:02:07-13:54:24 fw kernel: r8169: eth2: link down

...

I am trying to determine at this point if this is occuring because of faulty hardware or because of a driver issue or because I have that interface misconfigured on ASG or whatever.

Any help/suggestions on this would be greatly appreciated.

Thanks!