[Fwd: Re: 3 connections as one]

Luiz Otavio O Souza luiz at aonet.com.br
Thu Jun 26 13:33:36 UTC 2008

----- Original Message ----- 
Subject: Re: [Fwd: Re: 3 connections as one]

: Martes Wigglesworth wrote:
: > -------- Forwarded Message --------
: > From: Martes Wigglesworth <martes at mgwigglesworth.com>
: > Reply-To: martes at mgwigglesworth.com
: > To: Andres Chavez <fluxboxtremist at gmail.com>
: > Subject: Re: 3 connections as one
: > Date: Tue, 24 Jun 2008 16:34:04 -0400
: >
: > I have been researching this issue for almost a month now, and what I
: > have found is that you can bind the ports together for outbound traffic,
: > and the same can be done for inbound traffic, the problem comes when you
: > try to get the inbound packets, or sessions to dispurse across the
: > load-balanced ports. I.E.: Who is on the other side of the multiple
: > DSL/Cable links to filter the traffic across the associated pipes so as
: > to "balance the load," so to speak?
: >
: > It can be done, however, without an upstream, or maybe a vps that is
: > being used as an external gateway, you will not be able to get the
: > different session traffic to load balance across the multiple links,
: > when downloading.
: >
: > At least that seems to be the situation, without some nifty DNS tricks.
: > I have not seen how the "appliances" get around this, however, it took
: > me this long for either list that I was on, to even admitt that the
: > theory was not stupid, and to engage me in productive inquiry.
: the usual way is to NAT traffic out though each interface
: so that the internet is not aware that sessions from apparently
: different places are actually the same..
: you can do the same with multiple NAT instances and some way to divide
: up the load between interfaces..

I had write a patch, a long time before (probably in 4.x days - before 
libnat get the kernel bits) wich you can set two (fixed by patch at that 
time) alias address on natd.

Another option has been added to natd, a number wich can be set from 0 to 
100 to determine the use of the second alias address. This is intended to be 
used as "%", so 50 should be read as 50/50% balanced link.

So when a connection has to be established for the first time, the patch use 
the value of balance option to determine what alias address should be used 
for this new connection. The natd will use the default alias address or the 
optional alias address based on the "balance" set.

So natd is generating new connections in two diferent IPs (for two diferent 
connections) based on a "%" value, wich allow the use of unequal bandwidth 

At that time the patch work like a charm and is very usefull (as set 0/100 
disable the use of one link and 100/0 disable the use of the other link 
without change any other configuration).

Ipfw should be configured to deliver each IP/network to the proper gateway.

Due to the number of changes in recent libalias/natd the patch need to be 
rewrite and the only thing i am not happy (and IMHO should be revised is the 
number of connections that should be from 1 to any and not limited to two). 
This should be a simple task for a natd/libalias developer (not enough time 
for me).


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