None of the load balancing techniques I have come across seems to cover
'IP-Persistence'. For example, a session with several connections (for
which no conntrack-helper modules exist), will have problems, as its
connections will be routed through different WAN interfaces. Some
servers are very particular about the source IP of the packets they
receive. I suspect online gaming and instant messengers will have
problems with load balancing. How is the experience of other people in
here?
A rewrite of 'recent' match to include both source and destination may
turn out to be a solution, albeit with low performance. Any other ideas?
-----Original Message-----
From: lartc-bounces@mailman.ds9a.nl
[mailto:lartc-bounces@mailman.ds9a.nl] On Behalf Of Luciano Ruete
Sent: Tuesday, May 22, 2007 11:28 AM
To: lartc@mailman.ds9a.nl
Subject: Re: [LARTC] Multihome load balancing - kernel vs netfilter
On Monday 14 May 2007 02:57, Peter Rabbitson wrote:
> Hi,
> I have searched the archives on the topic, and it seems that the list
> gurus favor load balancing to be done in the kernel as opposed to
other
> means.
AFAIKR there aren't conflicting opinions, there are just to different
aproaches and i belive that routing solution is user cause it was the
first
and because sounds logical to implement multipath with your routing
tool.
But iptables has become in a routing tool so far (and much more).
Personaly im using multipath, but i do not dislike the iptables aproach.
> I have been using a home-grown approach, which splits traffic
> based on `-m statistic --mode random --probability X`, then CONNMARKs
> the individual connections and the kernel happily routes them. I
> understand that for > 2 links it will become impractical to calculate
a
> correct X.
well, is not impractical with a litle of scripting in your firewal...
#!/bin/bash
# your uplinks weight as in kernel multipath
# ie: link1 link2 link3 link4 link5
weight=" 1 2 1 3 5 "
weight_total=
for n in $weight ; do
let weight_total=weight_total+n
done
for n in $weight ; do
probability=$((n*100/weight_total))
echo iptables.. -m statistic --mode random --probability
$probability
done
but the problem arraise when you have lets say 101 links, cause mode
random
takes a 2 digit number right?, but this can be changed in the code (use
the
source...)
> But if we only have 2 gateways to the internet - are there
> any advantages in letting the kernel multipath scheduler do the
> balancing (with all the downsides of route caching), as opposed to the
> pure random approach described above?
Well, the disvantage i see is that you have to move all your routing
rules to
iptables space, but in the end you always need the routing table, but it
is a
mather of change old habits...
--
Luciano
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