On Fri, 2015-05-15 at 17:59 +0200, Johan Ymerson wrote:
> I have found a peculiar behaviour in ospfd when the physical link of the
> parent carp interface is down. The carp interface net is then announced
> with it's regular metric.
>
> An example:
> The cable of em2, parent of carp2 (192.168.254.0/23), is unplugged. Here
> is what is announced, seen by another machine running bird:
>
> router 192.168.200.4
> distance 10
> network 192.168.200.0/24 metric 10
> stubnet 192.168.202.0/24 metric 65535
> stubnet 192.168.254.0/23 metric 10
> stubnet 195.58.98.144/28 metric 65535
> stubnet 92.33.0.200/30 metric 65535
> stubnet 192.168.253.0/24 metric 10
>
> 192.168.254.0/23 is announced with metric 10. All other interfaces in
> the same carp group are announced with metric 65535 because the
> link-down state of em2 has demoted the carp group, as it should.
After reading my initial post I realize I wasn't clear about the result
of this.
If you have a redundant router set up with carp on one side and ospf on
the other, and plug out a network cable on the carp side on the master,
one will loose network connectivity to that network.
In our case we lost Internet access until we realized what was wrong and
shut down the master.
/Johan
>
> This behaviour is cased by the test for the carp state "down" doesn't
> check for link state "unknown".
>
> Here is a patch that prevents ospfd from announcing the interface when
> the physical interface is down. One could also argue that it should
> announce it with metric 65535, as in the carp backup state. But I feel
> it is better to not announce it at all since the link down state
> prevents us from becoming the master.
>
> Index: ospfe.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/ospfd/ospfe.c,v
> retrieving revision 1.90
> diff -u -p -r1.90 ospfe.c
> --- ospfe.c 10 Feb 2015 05:24:48 -0000 1.90
> +++ ospfe.c 15 May 2015 13:02:40 -0000
> @@ -880,7 +880,8 @@ orig_rtr_lsa(struct area *area)
> if (!(iface->flags & IFF_UP) ||
> (!LINK_STATE_IS_UP(iface->linkstate) &&
> !(iface->media_type == IFT_CARP &&
> - iface->linkstate == LINK_STATE_DOWN)))
> + iface->linkstate == LINK_STATE_DOWN)) ||
> + (iface->media_type == IFT_CARP &&
> iface->linkstate == LINK_STATE_UNKNOWN))
> continue;
> log_debug("orig_rtr_lsa: stub net, "
> "interface %s", iface->name);
>
>
> However, this if statement is difficult to understand as it is and
> should probably be rewritten, maybe something like this:
>
> Index: ospfe.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/ospfd/ospfe.c,vretrieving revision 1.90
> diff -u -p -r1.90 ospfe.c
> --- ospfe.c 10 Feb 2015 05:24:48 -0000 1.90
> +++ ospfe.c 15 May 2015 15:13:38 -0000
> @@ -877,11 +877,17 @@ orig_rtr_lsa(struct area *area)
> * backup carp interfaces have linkstate down, but
> * we still announce them.
> */
> - if (!(iface->flags & IFF_UP) ||
> - (!LINK_STATE_IS_UP(iface->linkstate) &&
> - !(iface->media_type == IFT_CARP &&
> - iface->linkstate == LINK_STATE_DOWN)))
> - continue;
> + if (!(iface->flags & IFF_UP))
> + continue; /* admin down */
> +
> + if (iface->media_type == IFT_CARP) {
> + if (iface->linkstate < LINK_STATE_DOWN)
> + continue; /* physical link down on carp if or
> invaild */
> + } else {
> + if (!LINK_STATE_IS_UP(iface->linkstate))
> + continue; /* UP or UNKNOWN */
> + }
> +
> log_debug("orig_rtr_lsa: stub net, "
> "interface %s", iface->name);
>
>
> Also, is the carp kernel code really correct when it leaves the
> interface link state as "unknown" when in carp init state?
>
> /Johan Ymerson
>
>
