[77676] in North American Network Operators' Group
Re: Rapidly-variable routing on the time scale of seconds to minutes?
daemon@ATHENA.MIT.EDU (James)
Mon Jan 31 22:09:06 2005
Date: Mon, 31 Jan 2005 22:08:39 -0500
From: James <haesu@towardex.com>
To: Charles Shen <charles@cs.columbia.edu>
Cc: 'John Fraizer' <nanog@enterzone.net>, nanog@merit.edu
In-Reply-To: <001d01c5080a$148bf960$37413b80@ccs>
Errors-To: owner-nanog-outgoing@merit.edu
On Mon, Jan 31, 2005 at 09:59:39PM -0500, Charles Shen wrote:
[ snip ]
>
> >From the responses, the answer to "the rapidly-variable routing on the time
> scale of seconds to minutes" seems to be:
>
> 1. It could be link layer load balancing, with the two interfaces belonging
> to the same router.
> 2. It could be per-flow load balancing where flows are defined via both L3
> and L4 info, so traceroute probe could not reflect the truth.
>
> My question is then: would it be safe to argue that the above two causes
> explain all (or most of?) the observed "fluttering" routers? (some examples
> listed below) What we are concerned about is per-packet load balancing
> (packets in the same flow go through different paths), which will cause
> trouble to protocols that install state information in routers along the
> flow path.
AFAIK, multiple routers showing up in a single-hop in traceroute response is
a sign of packet-by-packet load balancing, not flow based.
I could be wrong, though this was my past observation.
P.S.: What router-interacting applications are you using?
-J
--
James Jun TowardEX Technologies, Inc.
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