ospf cost and route selection (openospfd)
Josef Pojsl
jp at tns.cz
Wed Feb 6 06:56:51 PST 2008
Hello,
I am trying to use openospfd 4.0 over FreeBSD 6.2 in order
to provide redundancy for routing between LAN 1 and LAN 2.
The picture is as follows:
Locality 1 (LAN 1) Locality 2 (LAN 2)
WAN X
------------------------
Router 1 WAN Y Router 2
------------------------
Router 1 is connected to LAN 1 on one side
and to two WANs, X and Y, on the other side.
The same holds for Router 2, it is connected
to LAN 2, WAN X and WAN Y.
There are gre tunnels between the routers
over both WAN X and WAN Y. These tunnels get
encrypted with IPsec transport.
I have configured openospfd over both gre interfaces.
The preferred link that I would like to be used for routing
of LANs is the gre tunnel between 1 and 2 over WAN X.
The cost of that link is the least of both costs.
But, openospfd converges with routing between 1 and 2
over WAN Y, not WAN X. I have no clue why.
LAN 1 is 192.168.1.0/24, LAN 2 is 192.168.2.0/24.
gre30 is the link over WAN X, gre31 over WAN Y. 10.10.0.0/16 is WAN X,
10.20.0.0/16 is WAN Y.
Configuration of gre tunnels:
Router 1:
gre30: flags=b051<UP,POINTOPOINT,RUNNING,LINK0,LINK1,MULTICAST> mtu 1476
tunnel inet 10.10.1.2 --> 10.10.2.2
inet 10.30.1.2 --> 10.30.2.2 netmask 0xffffff00
gre31: flags=b051<UP,POINTOPOINT,RUNNING,LINK0,LINK1,MULTICAST> mtu 1476
tunnel inet 10.20.1.2 --> 10.20.2.2
inet 10.31.1.2 --> 10.31.2.2 netmask 0xffffff00
Router 2:
gre30: flags=b051<UP,POINTOPOINT,RUNNING,LINK0,LINK1,MULTICAST> mtu 1476
tunnel inet 10.10.2.2 --> 10.10.1.2
inet 10.30.2.2 --> 10.30.1.2 netmask 0xffffff00
gre31: flags=b051<UP,POINTOPOINT,RUNNING,LINK0,LINK1,MULTICAST> mtu 1476
tunnel inet 10.20.2.2 --> 10.20.1.2
inet 10.31.2.2 --> 10.31.1.2 netmask 0xffffff00
Configuration of openospfd:
Router 1:
router-id 0.0.0.1
redistribute connected
area 0.0.0.0 {
interface gre30 {
metric 20
}
interface gre31 {
metric 50
}
}
Router 2:
router-id 0.0.0.2
redistribute connected
area 0.0.0.0 {
interface gre30 {
metric 20
}
interface gre31 {
metric 50
}
}
ospfctl show rib:
Router 1:
Destination Nexthop Path Type Type Cost Uptime
0.0.0.2 10.31.2.2 Intra-Area Router 20 00:03:51
10.30.1.2/32 10.31.2.2 Intra-Area Network 40 00:03:41
10.31.1.2/32 10.31.2.2 Intra-Area Network 70 00:03:51
10.10.0.0/16 10.31.2.2 Type 1 ext Network 120 00:03:51
10.20.0.0/16 10.31.2.2 Type 1 ext Network 120 00:03:51
192.168.2.0/24 10.31.2.2 Type 1 ext Network 120 00:03:51
Router 2:
Destination Nexthop Path Type Type Cost Uptime
0.0.0.1 10.31.1.2 Intra-Area Router 20 00:04:51
10.30.2.2/32 10.31.1.2 Intra-Area Network 40 00:04:44
10.31.2.2/32 10.31.1.2 Intra-Area Network 70 00:04:51
10.10.0.0/16 10.31.1.2 Type 1 ext Network 120 00:04:51
10.20.0.0/16 10.31.1.2 Type 1 ext Network 120 00:04:51
192.168.1.0/24 10.31.1.2 Type 1 ext Network 120 00:04:51
ospfctl show interface detail:
Router 1:
Interface gre31, line protocol is UP
Internet address 10.31.1.2/24, Area 0.0.0.0
Linkstate unknown
Router ID 0.0.0.1, network type POINTOPOINT, cost: 50
Transmit delay is 1 sec(s), state P2P, priority 1
Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Backup Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Timer intervals configured, hello 10, dead 40, wait 40, retransmit 5
Hello timer due in 00:00:06
Uptime 00:06:04
Neighbor count is 1, adjacent neighbor count is 1
Interface gre30, line protocol is UP
Internet address 10.30.1.2/24, Area 0.0.0.0
Linkstate unknown
Router ID 0.0.0.1, network type POINTOPOINT, cost: 20
Transmit delay is 1 sec(s), state P2P, priority 1
Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Backup Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Timer intervals configured, hello 10, dead 40, wait 40, retransmit 5
Hello timer due in 00:00:06
Uptime 00:06:04
Neighbor count is 1, adjacent neighbor count is 1
Router 2:
Interface gre31, line protocol is UP
Internet address 10.31.2.2/24, Area 0.0.0.0
Linkstate unknown
Router ID 0.0.0.2, network type POINTOPOINT, cost: 50
Transmit delay is 1 sec(s), state P2P, priority 1
Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Backup Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Timer intervals configured, hello 10, dead 40, wait 40, retransmit 5
Hello timer due in 00:00:09
Uptime 00:06:02
Neighbor count is 1, adjacent neighbor count is 1
Interface gre30, line protocol is UP
Internet address 10.30.2.2/24, Area 0.0.0.0
Linkstate unknown
Router ID 0.0.0.2, network type POINTOPOINT, cost: 20
Transmit delay is 1 sec(s), state P2P, priority 1
Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Backup Designated Router (ID) 0.0.0.0, interface address 0.0.0.0
Timer intervals configured, hello 10, dead 40, wait 40, retransmit 5
Hello timer due in 00:00:09
Uptime 00:06:02
Neighbor count is 1, adjacent neighbor count is 1
Why the LANs get routed over gre31, having cost 50, and not over gre30
with lower cost 20? Has anybody got any clue?
Thanks in advance for any comments,
--
Josef Pojsl
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