Removing an alias can remove routes ?

[Mark Saad]

On Mon, Jan 14, 2019 at 11:59 AM Rodney W. Grimes
<freebsd-rwg at pdx.rh.cn85.dnsmgr.net> wrote:
>
> > All
> >  I ran into a peculiar over the weekend on two FreeBSD 10-STABLE
> > servers that has me at a loss. Both servers have the same setup  lacp
> > lagg wtih vlans using the lagg as a parent dev.
> > On the vlans I have some alias along with the primary ip.  When a
> > alias was added or deleted routes that sourced out of the primary ip
> > on that vlan were dropped from the routing table.
> >
> >
> > So for example. I have lagg0.vlan1044 . (both servers are similarly
> > configured as routers / firewalls )
> >
> >   [root at pineapple01 ~]# ifconfig lagg0.vlan1044
> >   lagg0.vlan1044: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST>
> > metric 0 mtu 1500
> >           options=300<TSO4,TSO6>
> >           ether 00:0f:53:20:9b:d0
> >           inet6 fe80::20f:53ff:fe20:9bd0%lagg0.vlan1044 prefixlen 64
> > scopeid 0x80
> >           inet 10.24.213.84 netmask 0xffffffe0 broadcast 10.24.213.95
> >           inet 10.24.212.129 netmask 0xffffffff broadcast 10.24.212.129
> >           inet 10.24.213.163 netmask 0xfffffff0 broadcast 10.24.213.175
> >           inet 10.24.213.76 netmask 0xffffffe0 broadcast 10.24.213.95
> >           inet 10.24.213.94 netmask 0xffffffe0 broadcast 10.24.213.95
> >           inet 10.24.213.89 netmask 0xffffffe0 broadcast 10.24.213.95
> >           inet 10.24.213.75 netmask 0xffffffe0 broadcast 10.24.213.95
> >           nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
> >           media: Ethernet autoselect
> >           status: active
> >           vlan: 1044 parent interface: lagg0
> >
> > [root at pineapple01 ~]# netstat -nr4Wl
> > ...
> >   192.168.144.32/27   10.24.213.65     UGS           0   1500 lagg0.vlan1044
> >   192.168.144.96/27   10.24.213.65     UGS           0   1500 lagg0.vlan1044
> >   192.168.23.0/24     10.24.213.65     UGS           0   1500 lagg0.vlan1044
> >   192.168.120.0/21   10.24.213.65     UGS           0   1500 lagg0.vlan1044
> >
> >
> > So I wanted to remove the alias ended in 163 and fix its netmask back to /32
> >
> > I ran this
> >
> > ifconfig lagg0.vlan1044 inet 10.24.213.163/24 -alias && ifconfig
>                                                       ^ delete?

I use -alias which is an alias of -delete

>
> > lagg0.vlan1044 inet 10.24.213.163/32 -alias
> >
> > and shortly there after all of the routes that went out lagg0.vlan1044
> > were gone . I quickly undid my change and put the routes back but I am
> > not sure what caused this ? Anyone have any ideas  I have done this in
> > the past with out issue and I am unsure whats changed other then the
> > box have a long up time of 463 days .
>
> I believe what happened here is that 10.24.213.163/24 when reduced
> to a network address is 10.24.213.0/24, which probably got sent to
> the route removal code, which since the route to that covers the
> gateway at 10.24.213.65 that gateway was no longer accessable
> so all routes via it got removed.
>

ok I see what you are saying and it makes sense to me; do you know why
the routing code does not see the primary ip ( the non-alias one) is
still
live on the interface before deciding to drop the routes associated with it ?


> --
> Rod Grimes                                                 rgrimes at freebsd.org



-- 
mark saad | nonesuch at longcount.org