OSPF routing testing

[hermanphang]

Hi All,

I try to design routing on 3 router using OSPF.

Why is not working if im using area 1 and area 2, however if im using area 0 and area 1 it work fine.

Is there are anyway to make this work.

I have attached my packet tracer sample.

Anyone that can help me out.

Thanks.

[cadet alain]

Hi,

Intra-area traffic must always traverse the backbone area which is area zero.

Regards

Alain

Don't forget to rate helpful posts.

[Richard Burts]

Cisco's implementation of OSPF is quite clear in its requirement that if there are multiple areas in OSPF that one area must be area 0.

What is happening is that each router is building an OSPF data base for each area to which it connects. So router11 has a set of entries for area 1 and a set of entries for area 2. But a router will not build the inter area summary entries (LSA type 3) unless it has a connection to area 0.

If you want to make this work with area 1 and area 2 you could configure both router12 and router13 with static default routes pointing to router 11. Since router 11 has entries for both areas it can route between areas and your network would work. But the better solution is to have one of the areas be area 0.

HTH

Rick

[hermanphang]

Thanks for Alain and Rick.

I have found 2 solution for my problem.

1. use subnet 255.255.255.255 on all router and it work.

2. separate OSPF process ID and used redistribute subnet on each OSPF process ID.

What is you opinion is the best solution?

or Anyone have other way instead of this two.

Thanks.

[Richard Burts]

1) I do not see how using subnet 255.255.255.255 on all routers would work.

2) I had not thought about using 2 OSPF processes and redistributing but if you are careful it could work ok. The biggest issue that you need to be careful about when doing mutual redistribution is the possibility of redistributing a route from 1 to 2 and then redistributing that route back from 2 to 1.

My opinion is that the best solution is to use area 0.

HTH

Rick

[hermanphang]

I just boradcast to all network 0.0.0.0 255.255.255.255 area 1 and network 0.0.0.0 255.255.255.255 area 2.

however when I show ospf database it show area 0 so that mean it automatically creating area 0.

It work find but I have some my concern the router will send broadcast to every router that connected.

Yes i agree, sometimes we have to try every possiblility how to make things work.

I think I need learn more about OSPF routing.

Thanks for your information.

[Kai Onken]

Hello hermanphang,

see at the attach sketch and try this configuration:

Router 1

interface loopback 10

description Router ID | OSPF 10

ip address 10.254.0.1 255.255.255.255

no shutdown

exit

!

interface fastEthernet 0/0

description Connection to Router R2 | Fa0/1

ip add 10.1.2.1 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/1

description Connection to Router R3 | Fa0/0

ip add 10.1.3.2 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/2

description Connection to local network

ip add 192.168.1.0 255.255.255.0

no shutdown

exit

!

ip routing

!

router ospf 10

router-id 10.254.0.1

network 10.254.0.1 0.0.0.0 area 0

network 10.1.2.0 0.0.0.3 area 0

network 10.1.3.0 0.0.0.3 area 0

network 192.168.1.0 0.0.0.255 area 1

exit

------------------------------------------------------------------

Router R2

interface loopback 10

description Router ID | OSPF 10

ip address 10.254.0.2 255.255.255.255

no shutdown

exit

!

interface fastEthernet 0/0

description Connection to Router R3 | Fa0/1

ip add 10.2.3.1 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/1

description Connection to Router R1 | Fa0/0

ip add 10.1.2.2 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/2

description Connection to local network

ip add 192.168.2.0 255.255.255.0

no shutdown

exit

!

ip routing

!

router ospf 10

router-id 10.254.0.2

network 10.254.0.2 0.0.0.0 area 0

network 10.1.2.0 0.0.0.3 area 0

network 10.2.3.0 0.0.0.3 area 0

network 192.168.2.0 0.0.0.255 area 2

exit

------------------------------------------------------------------

Router R3

interface loopback 10

description Router ID | OSPF 10

ip address 10.254.0.3 255.255.255.255

no shutdown

exit

!

interface fastEthernet 0/0

description Connection to Router R1 | Fa0/1

ip add 10.1.3.1 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/1

description Connection to Router R2 | Fa0/0

ip add 10.2.3.2 255.255.255.252

no shutdown

exit

!

interface fastEthernet 0/2

description Connection to local network

ip add 192.168.3.0 255.255.255.0

no shutdown

exit

!

ip routing

!

router ospf 10

router-id 10.254.0.3

network 10.254.0.3 0.0.0.0 area 0

network 10.1.3.0 0.0.0.3 area 0

network 10.2.3.0 0.0.0.3 area 0

network 192.168.3.0 0.0.0.255 area 3

exit