Date: Sat, 9 Aug 2008 08:37:22 -1000 From: Clifton Royston <cliftonr@lava.net> To: KES <kes-kes@yandex.ru> Cc: freebsd-stable@freebsd.org Subject: Re: Fwd: IMPORTANT! Network is unreachable Message-ID: <20080809183721.GA9982@lava.net> In-Reply-To: <358831218288212@webmail24.yandex.ru>
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On Sat, Aug 09, 2008 at 05:23:32PM +0400, KES wrote:
> 09.08.08, 16:22, "Matthew Seaman" <m.seaman@infracaninophile.co.uk>:
> > Andrew Snow wrote:
> > > Usually if there is more than IP in a given subnet on an interface, you
> > > give it a /32 netmask. Only the first IP in a subnet should have the
> > > full netmask.
> > >
> > > So your example should look like this:
> > >
> > > inet 10.11.16.14 netmask 0xffffff00 broadcast 10.11.16.255
> > > inet 10.11.16.9 netmask 0xffffffff broadcast 10.11.16.9
> > /32 netmasks for 2nd and subsequent IP alias addresses used to be
> > mandatory and are arguably more correct, but nowadays you can use
> > the actual netmask for the network instead. Was fixed a year or
> > two ago. It's a wetware compatibility thing -- other unixoid OSes
> > never had the /32 netmask requirement, and it kept tripping people up
> > when swapping between OSes.
> > Unfortunately I can't say exactly what the problem the OP is experiencing
> > is due to, but the way routes are appearing and disappearing on a 5
> > minute timescale does suggest dynamic routing problems to me. As a
> > work-around, if the OP wanted to override the information routed gets
> > from the network, then he could use /etc/gateways to have the local
> > routed append some static routes to the routing table -- see routed(8)
> > for the gory details. Losing a route for a directly attached network
> > looks like a bug to me though.
...
>
> > > inet 10.11.16.14 netmask 0xffffff00 broadcast 10.11.16.255
> > > inet 10.11.16.9 netmask 0xffffffff broadcast 10.11.16.9
> /24 mask on each IPs on same interfaces is working fine on FreeBSD 6.3
> So I do not think that problem is with the network mask. Because of even ping 10.11.16.14
> returns network is unreachable!
> Now when I upgraded to v7 I see trouble described earlier.
> So this is must be counted as BUG of v7
I happened to see recently a report of a similar problem with 7.0 on
a private mailing list. Again, there were multiple IP addresses
configured within the main subnet of the interface (this time
configured as /32s on other physical interfaces) and again, after a
while the system lost connectivity to its main subnet and "forgot" how
to ARP for addresses on the interface. An important similarity - the
routing info like yours showed the attached network with the G flag, as
being reachable via the gateway address within the same subnet.
I can't troubleshoot this, no access to the system in question, but I
thought it might help to know that others have run into the same
problem.
> The thing which is very interesting is:
> Why period is 5 min?
Might be something to do with ARP? Not sure.
-- Clifton
--
Clifton Royston -- cliftonr@iandicomputing.com / cliftonr@lava.net
President - I and I Computing * http://www.iandicomputing.com/
Custom programming, network design, systems and network consulting services
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