ethernet bonding problems

Steffen Persvold sp at scali.com
Fri Nov 1 04:06:45 EST 2002


On Thu, 31 Oct 2002, Trent Piepho wrote:

> On Thu, 31 Oct 2002, Glen Alan Kaukola wrote:
> > In the meantime, I would really appriciate it if anyone could provide me
> > any help or advice to get this working.  And one other thing, in talking
> > to someone on irc I was informed that ethernet bonding would not work at
> > all with two seperate switches like I have and would only work with a
> > managed switch.  A whole lot of the things I've read though on web pages
> > say otherwise.  So I'm wondering who's right?
> 
> It works with two unmanaged switches, I've got a setup like that right now. 
> It's using a managed switch you have to worry about, because some don't like
> the same MAC address appearing on different ports even if they are on
> different VLANs.
> 
> Has anyone found an increase in bandwidth from bonding gigabit channels?  It
> seems getting 100% usage out of just a single channel is hard to do, so I
> wonder if two will offer any improvement.  I did read something about someone
> getting about worse performance after bonding two gbit channels, because the
> packets then arrive out of order.
> 

As someone said to me once when I asked the same question "Welcome to the 
wonderful world of round-robin channel bonding". You are quite right, when 
using GbE channel bonding, IP fragments arrive out of order and initiates 
retransmits (TCP). Bottom line is that performance is worse than with one 
single channel. AFAIK it's not fixable with the current Linux IP stack.

Regards,
 -- 
  Steffen Persvold   |       Scali AS      
 mailto:sp at scali.com |  http://www.scali.com
Tel: (+47) 2262 8950 |   Olaf Helsets vei 6
Fax: (+47) 2262 8951 |   N0621 Oslo, NORWAY

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