Re: Round Robin Load Balancing

[Ramin Dousti <ramin@cannon.eng.us.uu.net>]

Absolutely. Perfect load balancing needs to be coordinated on _all_ the
endpoints of the links involved. In this case, 4 endpoints.

For a regular load balancing (which is going to be the case here)
we still have lots of unknown variables. Do these two ppp
accounts belong to the same ISP? Does the ISP drop forign src?
Is the gateway doing nat? Do you have any preference on one of
the ppp's than the other? Can you bond (mppp)? And so on.
But a fun project, though, for someone who has time...

Ramin

On Tue, Jul 15, 2003 at 12:44:40PM -0700, Daniel Chemko wrote:

> Because of the nature of your setup, you cannot have a perfect equal
> load balance setup. This is because you cannot control the inbound flow
> of data. If one user makes a request out of line X then the return
> packet HAS to come back through line X. So, if one guy sends a huge
> request taking minutes to fulfill, he / she will tie up the line until
> the job is finished. The load balancer should be smart enough to not
> send any more requests to that line, but you are still seeing the line
> being monopolized by this single connection, hence it is not balanced
> over all lines equally.
> 
> In order to have fair balancing of all lines, I think you need to set up
> a deal with your ISP to load balance on their end as well.
> 
> You could also setup something like BGP to allow multiple routes to the
> same return address, but I am not familiar enough with BGP to be much
> help in this area. In all likelihood, you are better off with your
> current solution or maybe the ISP solution if it is supported by them
> (more money usually).
> 
> 
> 
> -----Original Message-----
> From: Javier Govea [mailto:jgovea@magma.ca] 
> Sent: Tuesday, July 15, 2003 12:34 PM
> To: netfilter@lists.netfilter.org
> Subject: Round Robin Load Balancing 
> 
> Hi,
> 
> I'm trying to do some load balancing with four ppp connections. Here is
> what i have: a LAN
> connected to a redhat box which has four ppp interfaces. All the boxes
> in the LAN are
> accesing internet through the ppp interfaces in the redhat box. I'm
> using iproute2, in my
> redhat box, to setup the the four ppp interfaces as my default out going
> route (as
> described in LART http://lartc.org/howto/index.html) and I'm using
> iptables to masquerade
> all the traffic comming from the LAN. 
> 
> My setup is working fine, ie. my LAN can access the net throught the
> four ppp interfaces.
> My problem is that i don't know how is the load balancing working. Some
> times one of the
> ppp interfaces is used more than the others (and that is my problem).
> According to LART
> the routes are cached, can someone go a bit into more details in this
> caching thing??? how
> does it work?  which particular files in the kernel are doing this?  
> 
> I would like to implement a simple round robing algorithm (with no
> caching) for doing the
> laod balancing. That is first connection established gose through ppp0,
> the second
> connection on ppp1 and so on. 
> 
> I could hack iproute2 and/or iptables, but i'm not sure about which
> particular files i
> should hack in order to implement this round robin algorithm. I actually
> don't know if
> what i want makes any sense
> 
> Any ideas or pointers are all very well appreaciated.
> Thanx to all
> X
> 
>