CentOS - Sep 2008 - bonding theory question

Hello All,

I am currently using bonding with 2 NICs (using mode 0). Its been
working well, but I am trying to understand how it works (I am a total
newbie).

mode=0 (balance-rr)
Round-robin policy: Transmit packets in sequential order from the
first available slave through the last. This mode provides load
balancing and fault tolerance.


So I have 2 NICs (1 NIC attached to switch A, 2nd NIC attached to switch B).

I have 1 virtual interface. bon0.

Suppose data is being pushed out, it will go with 1st NIC and when it
gets overloaded it will use 2nd NIC. The bonding driver will be
responsible for it.

Similar to the push, the pull will be very similar. The data gets
pulled and the bonding driver will assemble the packets together? Does
this sound right?

Sorry for a newbie question...

TIA

On Sat, Sep 6, 2008 at 11:57, Mag Gam <magawake at gmail.com>
wrote:
> Suppose data is being pushed out, it will go with 1st NIC and when it
> gets overloaded it will use 2nd NIC.
No. If you are using "balance-rr", one packet will go through the 1st
NIC, and the next packet will go through the 2nd one. That's what
"rr"
(round-robin) means.
> Similar to the push, the pull will be very similar. The data gets
> pulled and the bonding driver will assemble the packets together? Does
> this sound right?
Actually this will not be determined by the bonding driver, it will be
determined by the switch that is actually "pushing" the packets. The
bonding driver will only make it look like the packets are coming from
one (bonded) interface only.

How the switch will behave depends on its configuration. It may be
configured to send all the data through one of the interfaces only to
balance through both of them using round-robin or something else.

You should try to read this, it's very complete:
/usr/share/doc/iputils-*/README.bonding

Also, if your switch supports it, you should try to use the 802.3ad
mode (mode=4) since that will probably give you the best results with
bonding (in terms of load balancing and fault tolerance).

HTH,
Filipe