Re: bonding mode 1 works as designed. Or not?

From: Heiko Gerstung
Date: Tue Feb 14 2006 - 16:51:00 EST

Hi Willy,

Willy Tarreau wrote:
[...]eth0 and eth1 are in a bonding group, mode=1, miimon=100 ... eth0 is the
active slave and used as long as the physical link is available (checked
by using MII monitoring), at the same time eth1 is totally passive,
neither passing any received packets to the kernel nor sending packets,
if the kernel wants it to do so. As soon as the eth0 link status changes
to "down", eth1 is activated and used, and now eth0 remains silent and
deaf until it becomes the active slave again.

Any comments on that? Is the documentation wrong OR is there a bug in
the implementation of the bonding module?

Neither, it's your understanding described above :-)
In fact, the bonding is used to select an OUTPUT device. If some trafic
manages to enter through the backup interface, it will reach the kernel.
It can be useful to implement some link health-checks for instance. However,
the only packets that you should receive are multicast and broadcast packets,
so this should be very limited anyway by design. After several years using
it, it has not caused me any trouble, including in environments involving
multicast for VRRP.

Unfortunately the ping replies come in on both interfaces, as well as any other traffic (like ssh or web traffic). Everything works but the load of the system caused by network traffic is nearly doubled this way and may cause confusion in a number of applications.

Would there be a way to stop the non-active slave(s) from "listening", i.e. drop all traffic received by them? If yes, where could I do that?

Thank you for your reply,
kind regards,

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