Re: Alternative to BGP-4 for multihoming?

["Peter A. van Oene" <vantech () sympatico ca>]

> > 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