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Re: Patch resubmission: RFC2863 operstatus for 2.5.50

To: Jeff Garzik <jgarzik@xxxxxxxxx>
Subject: Re: Patch resubmission: RFC2863 operstatus for 2.5.50
From: jamal <hadi@xxxxxxxxxx>
Date: Mon, 9 Dec 2002 08:27:39 -0500 (EST)
Cc: Stefan Rompf <srompf@xxxxxx>, "David S. Miller" <davem@xxxxxxxxxx>, <netdev@xxxxxxxxxxx>
In-reply-to: <3DEE3E6E.30407@pobox.com>
Sender: netdev-bounce@xxxxxxxxxxx


On Wed, 4 Dec 2002, Jeff Garzik wrote:

> jamal wrote:
> > Stefans curtrent patch makes the info available via netlink.
>
> He has two patches:  link change notification, and RFC2863 operstatus.
> I agree with the first one and support its inclusion; the second one I
> question its need.
>
> (just for context, I am referring to message <3DED2EA9.D812C881@xxxxxx>
> dated Dec 3)
>
>
> > What dont you like about it Jeff? Take a quick look at RFC2863
> > and scan for IfAdminStatus and IfOperStatus. The modelling RFC2863
> > has is pretty good and thats what Stefan has followed (after we weeded
> > a few crappy pieces off the RFC; we discussed on netdev).
>
> I had looked at ifAdminStatus and ifOperStatus before I posted :)
>
> My argument is, _after_ Stefan's link state patch is applied, why do we
> need the additional patch?  [this question is meant to be delivered in
> an honest, not snide way...]
>

I somehow deleted the original email he sent with the patches. What two
patches? I thought he had one which was a backport and another which
was for 2.5.x (sorry, i actually have seen those patches a few times so i
didnt bother reviewing anything); In any case, when you look at this stuff
think as well of devices that are software netddevices example VLANs or
PPP or some of the USB, Irda etc and you want the status properly
reflected (and some of that status may not make sense to ethernet for
example).

> For ifAdminStatus, you have "up", "down", and "testing" states.  Since
> we have no concept of a testing state, if we eliminate that we have "up"
> and "down", two states we can obviously handle.
>
> For ifOperStatus, we have "up", "down" and "testing", which are
> applicable (or not) to Linux as with ifAdminStatus.  Further we have
> states "dormant", "unknown", "notPresent", "lowerLayerDown".  I'll
> discuss each of these in detail.
>
> "dormant" - not used in Stefan's patch, which I agree with.
> "unknown" - only used in Stefan's patch before interface is first up'd,
> which is IMO inaccurate.  Accurate use of "up" and "down", to me,
> implies -no- use of "unknown" state.  Because as soon as we are
> initialized, all ethernet details are known, thus "down" is more
> applicable.  The Linux net stack's atomicity is such that leaking an
> "unknown" state would be a bug, too.
> "notPresent" - analagous to Linux's netif_device_xxx, and Stefan's patch
> acknowledges this.  However, the use of netif_device_xxx in drivers is
> really only used when the hardware is suspended.  If hardware goes away,
> the interface goes away too, almost immediately.
> "lowerLayerDown" - not used in Stefan's patch, which I agree with.
>
> So, Stefan's 2nd patch really only adds "unknown" and "notPresent"
> states to current behavior -- and the applicability of those states to
> Linux is IMO questionable.
>

If all he is adding are some enumerated types, theres no harm. I cant
remember the details of the discussions - but we had long winding
discussions on the different states.
Note you need both admin and operational status and physically thet may
mean different things (think PPP and ethernet for example). You also need
to properly reflect the status for all sorts of netdevices. As long as
those requirements are met, then all is good. The RFC is not the final
word but it draws from experiences people had for years doing this kind
of stuff - so it is a good idea to draw from their experiences (but ok to
ignore it if it sounds unrealistic).

cheers,
jamal



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