[151313] in North American Network Operators' Group
Re: Shim6, was: Re: filtering /48 is going to be necessary
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Thu Mar 15 15:04:33 2012
To: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
In-Reply-To: Your message of "Thu, 15 Mar 2012 21:52:54 +0900."
<4F61E626.80603@necom830.hpcl.titech.ac.jp>
From: Valdis.Kletnieks@vt.edu
Date: Thu, 15 Mar 2012 15:03:02 -0400
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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On Thu, 15 Mar 2012 21:52:54 +0900, Masataka Ohta said:
> > Get real. Even EAPS takes 0.05 seconds to recover from an unexpected
> > link failure
>
> If you keep two or more links, keep them alive, and let them
> know their IP addresses each other, which can be coordinated
> by mobile hosts as the ends, links can cooperate to avoid
> broken links for a lot faster recovery than 0.05s.
May work for detecting a dead access point in a wireless mesh, but
it doesn't scale to WAN sized connections.
Standard systems control theory tells us that you can't control a
system in less than 2*RTT across the network. There's *plenty* of
network paths where endpoint-homebase-endpoint will be over 50ms.
Consider the case where one endpoint is in Austria, the other is in Boston,
and the node handling the mobility is in Japan. Now a router fails in
Seattle. How long will it take for the endpoints to notice?
(Alternatively, explain how you locate a suitable home base node
closer than Japan. Remember in your explanation to consider that
you may not have a business relationship with the carrier that
would be an optimum location)
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