We moved a blade server running Red Hat Enterprise Linux 3 from one enclosure to another. The old enclosure had Nortel switches, the new enclosure had Cisco switches. After moving the server we noticed connectivity problems. Looking at the switches it appeared that the server’s MAC address was moving between the different switches. There were no errors on any of the interfaces. The server was configured for bonding with active-backup (mode 1). The relevant entries in /etc/ modules.conf read:
alias bond0 bonding mode=1 miimon=100 primary=eth0
Checking /proc/net/bonding/bond0 showed that it was actually using round robin mode (and that there had note been any link failures):
Bonding Mode: load balancing (round-robin)
In the end it seems to have been an issue with the entry in /etc/modules.conf. We changed it to:
alias bond0 bonding
options bond0 mode=1 miimon=100 primary=eth0
then restarted and that seems to have fixed the problem:
$ grep "Bonding Mode:" bond0
Bonding Mode: fault-tolerance (active-backup)
I’m not sure why it used to work fine before.
I also came across this http://www.experts-exchange.com/Networking/Linux_Networking/Q_24599062.html (hint to read this link, search for the URL in Google). It seems that the guy posting here had similar syntax and the same problem. If someone has access to Experts Exchange perhaps they can earn themselves some points by answering the question.
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