FTP server link aggregation

Nikos Vassiliadis nvass9573 at gmx.com
Thu Dec 16 10:54:43 UTC 2010

On 12/15/2010 3:11 PM, Matthew Law wrote:
> I have a single FreeBSD box acting as an FTP server for multiple FreeBSD
> and Linux clients on the same /24 subnet (all gigabit ethernet).  It is
> currently connected by just one of it's two gig ethernet ports.  I also
> have two cisco switches with an etherchannel between them (using 2 x gig
> ports on each switch).  I would like to connect the remaining NIC on my
> FreeBSD box to the other switch and enable 802.3ad on those switch ports
> to aggregate traffic between them.
> This is in the hope that it can better serve multiple FTP clients.  Is my
> thinking correct?  Other than the network interface changes which are
> documented here:
> http://www.freebsd.org/doc/handbook/network-aggregation.html are there any
> further tweaks I could make to improve things? -the server is a 'standard
> install' and does not use ZFS.  It has an adaptec 5408 RAID card with 4 x
> SATA II drives and, IIRC, 128K stripe size and plenty of RAM.
> Is there a way of testing this other than initiating large file transfers
> to this server from multiple hosts?

A simple ping from multiple sources to your server will do. LACP will
associate each SRCMAC and DSTMAC pair to one physical interface. Creating
traffic with many different SRCMAC and DSTMAC pairs will use both physical
interfaces. But, I do vaguely remember that if_lagg was not able to perform
at 2 * 1Gbps level. Use "systat -ifstat" to check what's happening and
please, post your performance findings to the list!

HTH, Nikos

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