On 2/04/2019 3:30 pm, Remi Locherer wrote:
> Hi Mitchell
>
> On Sat, Mar 30, 2019 at 04:10:09PM +1000, Mitchell Krome wrote:
>> I kept finding I had a lingering /30 route when I turned off one of my
>> test boxes. I tracked it down to ospfd sending RTM_ADD for a stub
>> network with the non-masked prefix. The RTM_ADD path applies the mask
>> inside the kernel, so the route got added as expected, but the
>> RTM_DELETE enforces an exact match, so it could never remove the route.
>>
>> The advertised stub network was as follows:
>>
>> Link connected to: Stub Network
>> Link ID (Network ID): 10.10.20.2
>> Link Data (Network Mask): 255.255.255.252
>> Metric: 10
>
> Please send the details of your setup so it is easy to reproduce the issue.
> - OpenBSD version
> - ospfd.conf
> - interface configs
> - routing table
I am running a kernel I compiled myself with source from ~2 weeks ago.
See the bottom for other info.
>
>> ospfd sends the interface address rather than network address as the
>> link ID. The RFC says "set the Link ID of the Type 3 link to the
>> subnet's IP address" which to me means we probably should also apply the
>> mask before we add the stub to the LSA to avoid getting into this place
>> to start with?
>
> This only applies to Type 3 LSAs. Below table is from RFC 2328
> chapter 12.1.4:
>
> LS Type Link State ID
> _______________________________________________
> 1 The originating router's Router ID.
> 2 The IP interface address of the
> network's Designated Router.
> 3 The destination network's IP address.
> 4 The Router ID of the described AS
> boundary router.
> 5 The destination network's IP address.
>
>>
>> The patch below just masks the stub network before it gets added to the
>> route table, so that we can properly delete it. I can send a patch to
>> mask it before sending the LSA too if the consensus is that is how it
>> should be.
>
> With your patch you change the case "LSA_TYPE_ROUTER" (LS Type 1) and not
> LS type 3.
Inside the LSA type 1 there is a type 3 link which is a "stub network".
That is what I was changing. Under 12.4.1.1 second dotpoint it says for
a point to point network add a type 3 link. Maybe I got the terminology
wrong, but this was definitely the thing I intended to change
Link type Description Link ID
__________________________________________________
1 Point-to-point Neighbor Router ID
link
2 Link to transit Interface address of
network Designated Router
3 Link to stub IP network number
network
4 Virtual link Neighbor Router ID
Table 18: Link descriptions in the
router-LSA.
>
> Remi
>
Box 1:
openbsd1# cat /etc/hostname.lo1
inet 10.0.0.1/32
openbsd1# cat /etc/hostname.gre0
up
mpls
tunnel 10.10.10.1 10.10.10.2
tunneldomain 10
inet 10.10.20.1/30
dest 10.10.20.2
openbsd1# cat /etc/ospfd.conf
area 0.0.0.0 {
interface lo1 {
passive
}
interface gre0
}
Box 2:
openbsd2# cat /etc/hostname.lo1
inet 10.0.0.2/32
openbsd2# cat /etc/hostname.gre0
up
mpls
tunnel 10.10.10.2 10.10.10.1
tunneldomain 10
inet 10.10.20.2/30
dest 10.10.20.1
openbsd2# cat /etc/hostname.gre1
up
mpls
tunnel 10.10.10.5 10.10.10.6
tunneldomain 10
inet 10.10.20.5/30
dest 10.10.20.6
openbsd2# cat /etc/ospfd.conf
area 0.0.0.0 {
interface lo1 {
passive
}
interface gre0
interface gre1
}
Box 3:
openbsd3# cat /etc/hostname.lo1
inet 10.0.0.3/32
openbsd3# cat /etc/hostname.gre0
up
mpls
tunnel 10.10.10.6 10.10.10.5
tunneldomain 10
inet 10.10.20.6/30
dest 10.10.20.5
openbsd3# cat /etc/ospfd.conf
area 0.0.0.0 {
interface lo1 {
passive
}
interface gre0
}
1: Box 1 has ospfd disabled. Route table on box 3:
openbsd3# route show
Routing tables
Internet:
Destination Gateway Flags Refs Use Mtu Prio Iface
10.0.0.2/32 10.10.20.5 UG 1 1 - 32 gre0
10.0.0.3 10.0.0.3 UHl 0 156 32768 1 lo1
10.10.20.0/30 10.10.20.5 UG 0 0 - 32 gre0
10.10.20.5 10.10.20.6 UHh 5 431 - 8 gre0
10.10.20.6 10.10.20.5 UHl 0 143 - 1 gre0
10.10.20.6/32 10.10.20.5 UG 0 0 - 32 gre0
localhost localhost UHl 0 12 32768 1 lo0
2: Enable ospfd on box 1. Note the /30 is still in the routing table,
but also the two /32 for each end of the link. ospfd produces the
following log message (see it's trying to delete the .2 address instead
of .0)
route 10.10.20.2/30 vanished before delete
openbsd3# route show
Routing tables
Internet:
Destination Gateway Flags Refs Use Mtu Prio Iface
10.0.0.1/32 10.10.20.5 UG 0 1 - 32 gre0
10.0.0.2/32 10.10.20.5 UG 1 24 - 32 gre0
10.0.0.3 10.0.0.3 UHl 0 179 32768 1 lo1
10.10.20.0/30 10.10.20.5 UG 0 0 - 32 gre0
10.10.20.1/32 10.10.20.5 UG 0 0 - 32 gre0
10.10.20.2/32 10.10.20.5 UG 0 0 - 32 gre0
10.10.20.5 10.10.20.6 UHh 11 456 - 8 gre0
10.10.20.6 10.10.20.5 UHl 0 147 - 1 gre0
10.10.20.6/32 10.10.20.5 UG 0 0 - 32 gre0
localhost localhost UHl 0 12 32768 1 lo0
3: Kill ospfd. Note the /30 is still there lingering
openbsd3# pkill ospfd
openbsd3# route show
Routing tables
Internet:
Destination Gateway Flags Refs Use Mtu Prio Iface
10.0.0.3 10.0.0.3 UHl 0 195 32768 1 lo1
10.10.20.0/30 10.10.20.5 UG 0 0 - 32 gre0
10.10.20.5 10.10.20.6 UHh 2 456 - 8 gre0
10.10.20.6 10.10.20.5 UHl 0 147 - 1 gre0
localhost localhost UHl 0 12 32768 1 lo0
