[zebra 23060] Re: OSPF on Freebsd with aliased interfaces generates NetworkMask mismatch

Whoops, I made a misstatement in my last post.

The solution works, but I followed up the nice work around with the foolish
comment 

	"After doing this, the host in question stops announcing the alias 
	address into OSPF.  But the address continues to work..."

I meant to say, it no longer announces the interface with the NetworkMask
mismatch.  It _IS_ obviously being announced into OSPF.  Just to follow this
up, the view from another host on the lan:

Vtysh> sh ip route
Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
       B - BGP, > - selected route, * - FIB route

O>* 10.0.0.107/32 [110/21] via 10.0.0.103, znb3, 07:01:25


Just curious, does anyone know what a FIB route is?


> -----Original Message-----
> From: Jim Carroll [mailto:[email protected]]
> Sent: Tuesday, August 28, 2007 10:48 PM
> To: '[email protected]'
> Subject: RE: OSPF on Freebsd with aliased interfaces generates
> NetworkMask mismatch
> 
> In deference to those who are having the same problem and stumble
> across this thread in the future, I've found a working solution.
> 
> The solution is to assigned the alias address to the loopback interface
> lo0.
> 
> In this example cited below, you would do the following:
> 
> Ecom3# ifconfig fxp0 10.0.0.103/22
> Ecom3# ifconfig lo0 10.0.0.107/32 alias
> 
> After doing this, the host in question stops announcing the alias
> address into OSPF.  But the address continues to work, and even shows
> up in a show ip route as an OSPF route !
> 
> 
> 
> > fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> >         inet 10.0.0.103 netmask 0xfffffc00 broadcast 10.0.3.255
> >         inet 10.0.0.107 netmask 0xffffffff broadcast 10.0.0.107
> >         ether 00:0e:0c:58:bf:24
> >         media: Ethernet autoselect (100baseTX <full-duplex>)
> >         status: active
> > lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> >         inet 127.0.0.1 netmask 0xff000000
> 
> > -----Original Message-----
> > From: Jim Carroll [mailto:[email protected]]
> > Sent: Tuesday, August 28, 2007 12:57 PM
> > To: '[email protected]'
> > Subject: OSPF on Freebsd with aliased interfaces generates
> NetworkMask
> > mismatch
> >
> > We have several web servers in our environment, each with multiple
> > aliases assigned to the same network.  We run OSPFv2.
> >
> > On FreeBSD, the aliased addresses are required to have a netmask of
> > 255.255.255.255.  Zebra/Ospf appears to grab the aliased interface
> > during it's inventory, and broadcasts Hello packets for each of the
> > aliases.  Since the netmask of the interface is different than the
> > primary netmask, every other machine on the network records a
> > NetworkMask mismatch in it's log file every few seconds.
> >
> > Here's the config of a sample machine.
> >
> > Ecom3> ifconfig -a
> > fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> >         inet 10.0.0.103 netmask 0xfffffc00 broadcast 10.0.3.255
> >         inet 10.0.0.107 netmask 0xffffffff broadcast 10.0.0.107
> >         ether 00:0e:0c:58:bf:24
> >         media: Ethernet autoselect (100baseTX <full-duplex>)
> >         status: active
> > lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> >         inet 127.0.0.1 netmask 0xff000000
> >
> >
> > zebra.conf
> > !
> > interface fxp0
> >     ip address 10.0.0.103/22
> >     multicast
> > !
> > interface lo0
> >
> >
> > ospfd.conf
> > !
> > interface fxp0
> >     ip ospf priority 0
> > !
> > interface lo0
> >     ip ospf priority 0
> > !
> > router ospf
> >     ospf router-id 10.0.0.103
> >     network 10.0.0.0/22 area 0.0.0.3
> >
> >
> > The error message recorded in log file of every neighbor on the
> > network:
> >
> >     ospfd[92553]: Packet 10.0.0.103 [Hello:RECV]: NetworkMask
> mismatch.
> >
> > Note: The above error message is generated once for each alias. So if
> > we have a web server with 10 aliases, each neighbor on the lan
> > generates 10 error messages in their log file every few seconds.
> >
> >
> > We're running:
> > 	FreeBSD 4.11-STABLE
> > 	Zebra 0.94 (i386-portbld-freebsd4.10).
> >
> > We've tried dozens of different combinations to resolve this.  I
> won't
> > bore you with the various combinations and details.
> >
> > I got excited when I saw a reference in the Unofficial FAQ to
> filtering
> > outbound announcements (http://pilot.org.ua/zebra/ospf.html),
> Question
> > 13
> >
> > 13.	Q: How do I filter incoming OSPF announcements ?
> >
> > 	A: Paul Jakma: You can't, only outgoing announcements may be
> > filtered.
> > 	(AFAIK - this is 	true. If it isn't true and you can filter
> > incoming OSPF
> > 	announcements, I'd love to be told!)
> >
> > But I'm stumped about how to about this.  I assume it would include a
> > Route-Map of some sort, but I can't get my head around how to
> > accomplish it.  If anyone has a quick snippet they could share, or a
> > pointer to where I could get more info on this configuration option,
> > I'd appreciate it.
> >
> > One other thing I should mention. All routing works!  At the moment,
> I
> > think this only means the log files get polluted with spurious error
> > messages.  From time-to-time we see small routing blips, so it's
> > possible the error above is contributing to a problem, but I doubt
> it.
> >
> > I've been reading FAQ's, docs and this list for quite awhile.  Every
> > few months, I check a server's log and am reminded about this issue,
> > and spend another 2 days looking into the problem.  This time around,
> I
> > thought I'd see if anyone might have insight into this issue.
> >
> > Thanks for any help or suggestions you can make.
> > Jim C.