On Tue, 2015-05-19 at 11:16 +0000, Johan Ymerson wrote:
> On Tue, 2015-05-19 at 11:24 +0100, Stuart Henderson wrote:
> > On 2015/05/19 10:10, Johan Ymerson wrote:
> >
> > Yes I understand that, but if carp init was counted in "LINK_STATE_DOWN"
> > then the metric would be 65535 which I think would still avoid the
> > problem you're seeing, and would involve less special-casing in ospfd.
> >
>
> Yes, that would also resolve the issue, but it is a bit illogical to
> announce a network we cannot possibly route traffic to (due to hardware
> problems).
>
> I had a look at how BGPd handles this, and it only looks at
> LINK_STATE_DOWN. It will also miss the case when
> linkstate==LINK_STATE_UNKNOWN.
> That brings us back to why the kernel's carp code doesn't initialize the
> linkstate to something more useful than UNKNOWN.
>
> /Johan
>
After some more testing I think we can conclude that this is most
definitely a kernel issue.
If the network cable is unplugged while the machine is running, ifconfig
reports the following:
carp2: flags=8803<UP,BROADCAST,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:5e:00:01:03
priority: 0
carp: INIT carpdev em2 vhid 3 advbase 1 advskew 100
groups: carp
status: invalid
inet 192.168.254.1 netmask 0xfffffe00 broadcast 192.168.255.255
In this case network is announced with the correct metric (65535).
However, if the machine is started with the cable unplugged, ifconfig
instead reports this:
carp2: flags=8803<UP,BROADCAST,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:5e:00:01:03
priority: 0
carp: INIT carpdev em2 vhid 3 advbase 1 advskew 100
groups: carp
inet 192.168.254.1 netmask 0xfffffe00 broadcast 192.168.255.255
In this case the network is incorrectly announced as available with low
metric.
Initializing if_link_state in the kernel carp code does seem to fix the
issue:
Index: sys/netinet/ip_carp.c
===================================================================
RCS file: /cvs/src/sys/netinet/ip_carp.c,v
retrieving revision 1.247
diff -u -p -r1.247 ip_carp.c
--- sys/netinet/ip_carp.c 4 Mar 2015 10:59:52 -0000 1.247
+++ sys/netinet/ip_carp.c 19 May 2015 17:22:18 -0000
@@ -751,6 +751,7 @@ carp_clone_create(ifc, unit)
ifp->if_addrlen = ETHER_ADDR_LEN;
ifp->if_hdrlen = ETHER_HDR_LEN;
ifp->if_mtu = ETHERMTU;
+ ifp->if_link_state = LINK_STATE_INVALID;
IFQ_SET_MAXLEN(&ifp->if_snd, IFQ_MAXLEN);
IFQ_SET_READY(&ifp->if_snd);
if_attach(ifp);
/Johan
/Johan
