Difficult to do this on the same LAN (172.16.0.0/24). OSPF cost affects on receive. So if you make ‘ip ospf cost XX’ on port, it will affect all costs…
OSPF prefers Intra-Area routes over Inter-Area routes.
So, what we can do… Put R4 and R3’s fastethernet interface on an other area. Area 1 for example. R4’s loopback still on area 0 :
R4#sh run | inc interface (Fa|Lo)|_ip ospf
interface Loopback0
ip ospf 1 area 0
interface FastEthernet0/0
ip ospf 1 area 0
interface FastEthernet0/1
ip ospf 1 area 1
And from R1 :
R1#sh ip route ospf
99.0.0.0/32 is subnetted, 1 subnets
O 99.99.99.1 [110/21] via 172.16.0.2, 00:13:56, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
O 10.24.0.0 [110/20] via 172.16.0.2, 00:18:25, FastEthernet0/0
O IA 10.34.0.0 [110/20] via 172.16.0.3, 00:15:28, FastEthernet0/0
R1#traceroute 99.99.99.1
Type escape sequence to abort.
Tracing the route to 99.99.99.1
Changing the interfaces network type of 172.16.0.0/24 LAN to Point-to-Multipoint, so we can manually put a lower cost with the neighbor command to R2 ?
Using different weight (less for preferred route)?
Hi Lorenzo,
Difficult to do this on the same LAN (172.16.0.0/24). OSPF cost affects on receive. So if you make ‘ip ospf cost XX’ on port, it will affect all costs…
Regards,
Christophe
That’s true. But you can change the cost on R2 and R3 ports.
You will influence the return path, not the forward path.
You will have :
R1#traceroute 99.99.99.0
Type escape sequence to abort.
Tracing the route to 99.99.99.0
1 172.16.0.3 288 msec
172.16.0.2 400 msec
172.16.0.3 1124 msec
2 10.24.0.4 636 msec
10.34.0.4 260 msec
10.24.0.4 436 msec
R1#
Regards,
Christophe
Mhh…you are right.
If R1 is high end router, you can run OSPF LFA. Otherwise I have no idea 🙂
What is the OSPF type of network on 172.16.0.0/24 ?
forget ospf, but a static route :p
Hi Johan,
It is an answer but not the right answer. Only with OSPF 😉
Regards,
Christophe
wasn’t mentionned in the challenge ;p
it is true. It is more challenging only in OSPF.
Christophe
Create two different vlans (one for each router) with subinterfaces and the trath each one as different interface with different weigth.
What do you think about that?
It is another solution, but you can do it on the same lan.
Regards,
OSPF prefers Intra-Area routes over Inter-Area routes.
So, what we can do… Put R4 and R3’s fastethernet interface on an other area. Area 1 for example. R4’s loopback still on area 0 :
R4#sh run | inc interface (Fa|Lo)|_ip ospf
interface Loopback0
ip ospf 1 area 0
interface FastEthernet0/0
ip ospf 1 area 0
interface FastEthernet0/1
ip ospf 1 area 1
And from R1 :
R1#sh ip route ospf
99.0.0.0/32 is subnetted, 1 subnets
O 99.99.99.1 [110/21] via 172.16.0.2, 00:13:56, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
O 10.24.0.0 [110/20] via 172.16.0.2, 00:18:25, FastEthernet0/0
O IA 10.34.0.0 [110/20] via 172.16.0.3, 00:15:28, FastEthernet0/0
R1#traceroute 99.99.99.1
Type escape sequence to abort.
Tracing the route to 99.99.99.1
1 172.16.0.2 40 msec 28 msec 20 msec
2 10.24.0.4 28 msec 36 msec 40 msec
Am I right ?
You can do this way, but there is a solution to make prefer R2 in the same area (area 0).
Have fun to fond the solution.
Regards,
Christophe
Changing the interfaces network type of 172.16.0.0/24 LAN to Point-to-Multipoint, so we can manually put a lower cost with the neighbor command to R2 ?
Yeah !!! It is the solution 🙂