Use lagg(4) or Use Layer-4 Load Balancing?

[Andrew Thompson]

On Tue, Jun 17, 2008 at 04:32:03AM -0400, Martes G Wigglesworth wrote:
> Greetings all.
> 
> I have been attempting to research what  I have been informed is
> actually accomplished with layer-4 load balancing.  I have seen many
> articles and reviews that indicate that lagg(4) will accomplish the
> teaming of multiple internet access sorces into a single logical pipe,
> however, I have tried this using a dumb switch two nic interfaces and
> this simply is not the case.  
> 
> I am new and may not have enough cool equipment around, however, aside
> from using the fail-over mode for redundancy, and lacp on a supported
> switch, then if lagg(4) could really combine multiple sources into one
> for use as a larger overall backbone, then I should be able to get
> doulbed bandwidth using two separate ports on an unmanaged switch using
> some option on the lagg(4) driver, which is not the cast.(if this is
> wrong I would be happy to get the correct information, however I have a
> few network engineer references that say that you cannot do anything
> more than layer-2 lacp with appropriate equipment to create an
> isp-supported trunk)  Even in the on-lamp interview the 7.0 developer
> implies that you can do what I am attempting to research however, it is
> not possible at layer 2 without an end-point.

How are you testing this? You need to have multiple IP flows in order to
fully utilise the multiple links. See this snippet from the handbook
(i'll put it in the man page too).

"Since frame ordering is mandatory on Ethernet links then any traffic
between two stations always flows over the same physical link limiting
the maximum speed to that of one interface. The transmit algorithm
attempts to use as much information as it can to distinguish different
traffic flows and balance across the available interfaces."


Does that answer your question, you will not get more speed on a single
download.


Andrew