[CentOS] Best practice settings for channel bonding interface mode?

nate centos at linuxpowered.net
Wed Oct 14 13:00:55 UTC 2009

Götz Reinicke - IT-Koordinator wrote:
> E.g. I do have some fileservers connected to the users lan and to some
> ISCSI Storages. Or some Webservers only connected to the LAN. The
> switches are all new cisco models.

For me the only valid bonding modes to use are:

- active/backup
- 802.3ad

If you have systems using iSCSI, I strongly reccomend using
dedicated NICs for accessing iSCSI and putting them in VLANs
that have jumbo frames enabled, and enable jumbo frames on the iSCSI
targets. The nice thing about iSCSI is since it runs on top of
TCP you can configure your iSCSI system to use jumbo frames and
both standard frame and jumbo frame systems can talk to it because
TCP has MTU negotiation(forget what the real name is called).

Note that 802.3ad will not provide any higher throughput than
1 link in the bond can do to a single ip/port. It is meant for
many:1 improvement in throughput. If you have 802.3ad on the
client side and say your iSCSI target uses 802.3ad as well, and
everything is GbE, you won't get more than 1GbE of throughput
even if you have 8 ports in a bond/trunk.

For faster throughput than 1GbE between hosts I suggest going
to 10GbaseT, which allows 10GbE speeds on CAT5e up to 55 meters,
and CAT6a up to 100 meters. Really makes for cost effective
10GbE. There aren't many 10GbE NICs on the market yet that
can use 10GbE over UTP (Chelsio is one vendor that I know of).

Active/backup is pretty simple, you typically have 1 link that
is active the other is standby, by default if the system
detects the first link going down it switches over in about
a second or so.


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