From owner-freebsd-net  Sat May 29  4:12:13 1999
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Date: Sat, 29 May 1999 13:11:31 +0200
From: Andreas Klemm <andreas@klemm.gtn.com>
To: freebsd-net@FreeBSD.ORG, zebra@zebra.org,
	Kunihiro Ishiguro <kunihiro@zebra.org>
Subject: Re: OSPF eequal-cost paths, which algorithm, how exactly load balancing ?
Message-ID: <19990529131131.A8802@titan.klemm.gtn.com>
References: <19990528084002.A41138@titan.klemm.gtn.com>
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In-Reply-To: <19990528084002.A41138@titan.klemm.gtn.com>; from Andreas Klemm on Fri, May 28, 1999 at 08:40:02AM +0200
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Hi,

thanks for the many people answering.

I learned the following:

	a) turning off the fast cache on a Cisco Router with two 2 MBit
	   serial lines puts too much load on the CPU and isn't suggested.

	b) The routing protocol only fills the routing table with 
	   two paths for the destination router / network. How the
	   packets travel to the dstination network is a matter of
	   the router operating system (IOS)...

	c) If the first packet arrives on the source router (the one
	   who sits on the backbone from which two equal-cost paths
	   lead to the destination router) the router doesn't find an
	   entry in the fast cache and has to look up the routing-table.
	   When finding a route it makes a "random" decision, which path
	   to use, transmits the packet and makes an entry in the fast cache.

	d) the entry of the fast cache usually has a lifetime of about 10-15
	   seconds. Subsequent packets will choose the path which is
	   in the fast cache which, and the fast cache will life for another
	   10-15 seconds.

	e) If no subsequent packets arrive the fast-cache times out.
	   If a new packet arrives for the destination it starts again
	   at c)...

So my initial question wasn't correct, assuming the routing protocol
had something to do with the transport through path 1 or 2 ...

I thought I should give you something back, after increasing my
learning courve ;-)

Thanks again

	Andreas ///

-- 
Andreas Klemm                               http://www.FreeBSD.ORG/~andreas
                                  http://www.freebsd.org/~fsmp/SMP/SMP.html
                                powered by Symmetric MultiProcessor FreeBSD


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