[27785] in North American Network Operators' Group
Re: Alternative to BGP-4 for multihoming?
daemon@ATHENA.MIT.EDU (Peter A. van Oene)
Mon Mar 13 16:59:07 2000
Message-ID: <200003131655270140.0F186789@smtp1.sympatico.ca>
In-Reply-To: <g3k8j7mlqd.fsf@redpaul.mibh.net>
Date: Mon, 13 Mar 2000 16:55:27 -0500
From: "Peter A. van Oene" <vantech@sympatico.ca>
To: "Paul Vixie" <vixie@mibh.net>, nanog@merit.edu
Content-Type: text/plain; charset="us-ascii"
Errors-To: owner-nanog-outgoing@merit.edu
>
>> Its these cases I'm concerned with. In my mind, irrespective of the
>> comments on the functionality of DNS for this purpose, I see little
other
>> choice.
>
>DNS is not the droid you're looking for.
>
>Using DNS response times to predict likely TCP performance is silly for at
>least as many reasons as using BGP aspath lengths to predict likely TCP
>performance is silly.
>
>> That being said, if anyone has better ideas on how to provide for high
>> availability to millions of web sites worldwide, please let me know.
>
>TCP performance is affected by congestion symmetry, since TCP uses the
>spacing of ACK packets to control the spacing of data packets. While
>there's no way to guarantee congestion symmetry, one of the leading
>indicators of whether you will have congestion symmetry is "whether you
>have path symmetry." Furthermore, the leading indicator of whether you
>have path symmetry is "whether the outbound flow's first hop is the same
>as the incoming flow's last hop."
>
Just a quick note in clarification, I am less interested in intelligently
directing the traffic to the closest or most optimal server farm that I am
in purely ensuring that the traffic can be balance between sites that sit
within different AS's.
-------
Peter Van Oene
Senior Systems Engineer
UNIS LUMIN Inc.
www.unislumin.com
