[129077] in North American Network Operators' Group
Re: Should routers send redirects by default?
daemon@ATHENA.MIT.EDU (Mark Smith)
Wed Aug 25 18:10:16 2010
Date: Thu, 26 Aug 2010 07:35:53 +0930
From: Mark Smith <nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org>
To: Christopher Morrow <christopher.morrow@gmail.com>
In-Reply-To: <AANLkTini0DxcZvO4EzGBvMMFGLBSWA1NhNxQCWy5YpiD@mail.gmail.com>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Wed, 25 Aug 2010 01:18:15 -0400
Christopher Morrow <christopher.morrow@gmail.com> wrote:
> On Tue, Aug 24, 2010 at 4:32 PM, William Herrin <bill@herrin.us> wrote:
> > On Fri, Aug 20, 2010 at 1:20 PM, Christopher Morrow
> > <christopher.morrow@gmail.com> wrote:
> >> Polling a little bit here, there's an active discussion going on
> >> 6man@ietf about whether or not v6 routers should:
> >> =C2=A0o be required to implement ip redirect functions (icmpv6 redirec=
t)
> >> =C2=A0o be sending these by default
> >
> > Hi Chris,
> >
> > If you don't mind, I'd like to ask a similar question whose answers
> > might be instructive for the question you asked:
>=20
> sure :) (other folks should also chime in, or I thought that was the
> spirit of your question...)
>=20
> >
> > Forgetting all of the theoretical constructs for a moment, has anyone
> > here personally encountered an operational scenario in which ICMP
> > redirects solved a problem for you that you would otherwise have found
> > difficult or intransigent? Without naming names, would you describe
> > the scenario's details, explain the problem that would have existed
> > absent redirects and explain how redirects solved it for you?
>=20
> I've never had redirects solve a problem for me.
>=20
So how do you know?
If redirects are enabled by default, then they may have fixed a problem
for you that you didn't know existed and never realised existed. When
your packets get there successfully you don't go and investigate why.
You only troubleshoot failure, not success.
I think the only way to know an absolute answer would be to
have witnessed this sequence of events=20
- have an environment where redirects are switched off
- suffer from a problem that redirects are designed to solve
- switch redirects on and have the problem not disappear
Of course, the problem not disappearing when redirects are enabled might
also mean a misdiagnosis of what the problem really is.
Regards,
Mark.
