I four nodes setup to do active-backup bonding and the drivers loaded for the bonded network interfaces vary between tg3 and e100. All interfaces with the e100 driver loaded report errors much like what you see here: bonding: bond0: link status definitely down for interface eth2, disabling it e100: eth2: e100_watchdog: link up, 100Mbps, full-duplex bonding: bond0: link status definitely up for interface eth2. This happens all day on every node. I have configured the bonding module to do MII link monitoring at a frequency of 100 milliseconds and it is using basic carrier link detection to test if the interface is alive or not. There was no custom building of any modules on these nodes and the o/s is CentOS 4.3. Some more relevant information is below (this display is consistent across all nodes): [smccl at tf35 ~]$uname -srvmpio Linux 2.6.9-34.ELhugemem #1 SMP Wed Mar 8 00:47:12 CST 2006 i686 i686 i386 GNU/Linux [smccl at tf35 ~]$head -5 /etc/modprobe.conf alias bond0 bonding options bonding miimon=100 mode=1 alias eth0 tg3 alias eth1 tg3 alias eth2 e100 [smccl at tf35 ~]$cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v2.6.1 (October 29, 2004) Bonding Mode: fault-tolerance (active-backup) Primary Slave: None Currently Active Slave: eth0 MII Status: up MII Polling Interval (ms): 100 Up Delay (ms): 0 Down Delay (ms): 0 Slave Interface: eth0 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:10:18:0c:86:a4 Slave Interface: eth2 MII Status: up Link Failure Count: 12 Permanent HW addr: 00:02:55:ac:a2:ea Any idea why these e100 links report failures so often? They are directly plugged into a Cisco Catalyst 4506. Thanks.