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Re: [Xen-users] bonding with trunking AND iscsi

On 02/11/11 03:39, Fajar A. Nugraha wrote:
> On Fri, Feb 11, 2011 at 6:16 AM, Linus van Geuns <linus@xxxxxxxxxxxxx
> <mailto:linus@xxxxxxxxxxxxx>> wrote:
>     Hey Donny,
>     as Jeff already stated, you can bond multiple NICs connected to the
>     same switch to a single trunk/logical link and put VLAN interfaces on
>     top of that (with some hacks - see the kernel doc on bonding).
>     The LACP link aggregation might not scale the bandwidth as you
>     expect it to.
>     For each packet, the bonding code decides which slave (NIC) to use for
>     output using a hash calculated from layer2(MAC), layer2+3(MAC+IP) or
>     layer3+4(IP+ports). This means a single packet flow (eg I/O traffic
>     with a single iSCSI target) from one host to another will never use
>     more than one NIC (bandwidth).
>     In fact, as there is no dynamic load balancing or round robin, you
>     might even share one NIC for multiple iSCSI packet flows and have the
>     other slaves (NICs) idle.
> I'm pretty sure you can choose round robin in Linux. From iputils'
> README.bonding: 
> mode
>         Specifies one of the bonding policies. The default is
>         balance-rr (round robin).  Possible values are:
>         balance-rr or 0
>                 Round-robin policy: Transmit packets in sequential
>                 order from the first available slave through the
>                 last.  This mode provides load balancing and fault
>                 tolerance.
>     This is why I dropped the VLAN over LACP trunk idea. ;-)
> IMHO VLAN over bonding is a good idea. Just make sure you manage the
> setup using OS' configuration (/etc/sysconfig/network-scripts/ifcfg-* on
> RH), and NOT rely on xend's default network-bridge script.
> -- 
> Fajar
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I use it and it provides me with almost double the bandwidth. For rr you
need to use different switches do, or switch to 802.3ad mode and use a
switch that supports it.


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