[c-nsp] General switching question regarding load balancing host

[Phil Mayers]

On 17/09/10 17:12, Gert Doering wrote:
> Hi,
>
> On Fri, Sep 17, 2010 at 11:52:41AM -0400, Jay Nakamura wrote:
>> Some hosts/OS can do load balancing between NICs.  If a host has two
>> NICs connected to two switches,(the two switches are connected
>> together) and load balancing between them, switch will see the same
>> source MAC from two ports.
>
> Don't do this.

Agreed

>
> If the ports go to two different switches (that cannot do cross-chassis
> etherchannel), use active/passive bundling, not load-sharing.

Just for completeness: under OSes like Linux, there are a few 
weird/esoteric NIC load-balancing methods that *claim* to work - usually 
where all the traffic comes in a single NIC, but is load-balanced out of 
multiple NICs with the source MAC address of each egress NIC, not the 
attached layer3 interface. I would avoid like the plague and stick to 
active/passive.