RE: [LARTC] Problem with Load Balancing

[William T Mullaney <wtm@harbec.com>]

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Well, if you had a download manager and the system at the other side allowed
you to start your transfers in the middle of the file (which isn't out of
the question) that could potentially work.  The problem is that as far as I
see, there's nothing to force the second connection onto the second line.
It's been kind of a crap shoot of what line gets more information.  In
theory you could start the first download stream (and it's routed to ISP A),
then perhaps your email client goes out to check your POP account, so that
goes over ISP B.  The next connection, the second stream, now goes out over
ISP B again.  Honestly I don't know exactly how the equalize command for ip
route works, though I would think it says to always use the "less used"
connection (perhaps on PPS, BPS, % use, whatever, on a per second, 30
second, minute average?), but in my experience that and the weight options
don't ever get you exactly 50/50 (or whatever you specify) traffic.  

Things like bit torrent would probably perform better because there are
(possibly) many streams for each file, as would having 50 people downloading
files vs one.  It seems to be just like rolling dice, if you only roll twice
you might get two evens or two odds, but if you roll tons of times, you
should tend to get a more even distribution. 

-Will

-----Original Message-----
From: Raj Mathur [mailto:raju@linux-delhi.org] 
Sent: Sunday, September 24, 2006 2:49 PM
To: lartc@mailman.ds9a.nl
Subject: RE: [LARTC] Problem with Load Balancing

>>>>> "William" == William T Mullaney <William> writes:

    William> To my knowledge, there is no way to download one file
    William> from two different connections connected to two different
    William> ISPs at the same time.  If you are running BGP then you
    William> might be able to load balance across the two links, but
    William> that would require your upstream providers to allow you
    William> to use it, and possibly the purchase of a public AS
    William> number an IP address space depending on the setup.  If
    William> you are doing NAT past this link (IE both of your lines
    William> go two the same ISP and same address blocks, but they
    William> want to give you 2x 10mb links for 20mb total), then you
    William> can look at doing load balancing on layer 2 (Fast
    William> EtherChannel, bonding, Link Aggregate Groups, whatever),
    William> or creating 2 PPP style links between the computers and
    William> using a routing protocol like OSPF, EIGRP (but not on
    William> Linux) or something.  I believe OSPF does equal cost load
    William> balancing, BGP and EIGRP can, I think, do unequal cost
    William> load balancing.  But either way, I don't think that's the
    William> solution in your case.

    William> The only other option I can think of would be some sort
    William> of software that sends every other packet to a different
    William> IP or something, which would need to run at the end you
    William> are downloading at or maybe at your ISPs, but I can't
    William> think of anything like that.

Wouldn't some download manager software that splits the file up into
multiple simultaneous downloads do the trick?  Agreed, not a single download
across multiple ISPs, but definitely a single file across multiple ISPs.

Regards,

-- Raju
-- 
Raj Mathur                raju@kandalaya.org      http://kandalaya.org/
       GPG: 78D4 FC67 367F 40E2 0DD5  0FEF C968 D0EF CC68 D17F
                      It is the mind that moves
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