svn commit: r334875 - head/sys/net

Rodney W. Grimes freebsd at pdx.rh.CN85.dnsmgr.net
Wed Jun 13 07:30:01 UTC 2018


> On 09.06.2018 15:26, Rodney W. Grimes wrote:
> >> Author: ae
> >> Date: Sat Jun  9 09:57:14 2018
> >> New Revision: 334875
> >> URL: https://svnweb.freebsd.org/changeset/base/334875
> >>
> >> Log:
> >>   Explicitly change the link state when we assingn an address.
> >>   
> >>   Since we are setting IFF_UP flag on SIOCSIFADDR, it is possible, that
> >>   after this link state information still not initialized properly.
> >>   This leads to problems with routing, since now interface has
> >>   IFCAP_LINKSTATE capability and a route is considered as working only
> >>   when interface's link state is in LINK_STATE_UP (see RT_LINK_IS_UP()
> >>   macro).
> > 
> > I was going to say something when the ability to up and down
> > the loopback interfaces was added as it perturbed me but I
> > could not put my finger on places it may cause problems so
> > remained silent on the matter.
> > 
> > Now that I see this issue, having lo0 go DOWN can kill a network
> > that is using exported from lo0 into a routing protocol routes that 
> > are used for management purposes.
> 
> This was one of the main reasons of this change.
> 
> > How does Cisco, Juniper, etc at handle this?
> > Do any of them or all of them allow you to "down" loopback?
> 
> AFAIK, they allow this.

Confirmed as far as you can "shutdown/no shutdown" a loopback
device on Cisco, but I am not sure that is the same as the
LINK_STATE_UP/DOWN.

I am fine with it as it is now, but we need to keep an eye
on it for any issues.

-- 
Rod Grimes                                                 rgrimes at freebsd.org


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