[Beowulf] Channel bonding, again
kilian at stanford.edu
Fri Oct 12 09:53:06 PDT 2007
On Friday 12 October 2007 04:57:50 am Henning Fehrmann wrote:
> On the other hand, one needs to trunk (HP calls it trunking) the
> ports on the switches. We tried it on HP and Cisco switches.
> The switch collects the packages of the trunked ports and
> redistributes them according to a level 2 or level 3 hash policy.
> Here starts the problem: the packages are coming with the same IP-
> and MAC-address. The switch gets confused and, furthermore, the
> switch wants to do the work which is already done by the node.
I think LACP (802.3ad)  is supposed to address these issues: it
allows swicthes to negotiate an automatic configuration of individual
ports by exchanging LACP packets with the peer. From the switch
standpoint, a LACP port group is considered as a single logical port,
which kind of alleviate those multiple-ports-same-address problems,
while conserving the advantages of increased bandwidth and failover if
one individual link fails.
LACP is supported by Cisco  and Dell  switches, and for the peer
side, by the Linux bonding module (mode 4) , the FreeSBD lagg(4)
driver (>= 6.2-STABLE)  and by NetBSD agr(4) .
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