Re: 2 ospf link on the same physical link

[Acee Lindem <[e-mail]>]

Sandor,

Some vendors support OSPF on secondary IP addresses and others
do not. Refer to the list post below.

http://discuss.microsoft.com/SCRIPTS/WA-MSD.EXE?A2=ind0203&L=ospf&T=0&F=&S=&P=3918

The draft below proposes a way of supporting a single link in multiple
areas as a way of getting around the primary address limitation (among
other benefits).

http://www.ietf.org/internet-drafts/draft-ietf-ospf-mlinks-03.txt

Thanks,
Acee


Sandor Ecker wrote:

> Hello!
>
> I have tried the following on zebra (redhat linux), and on cisco routers too.
> I had a simple ip link (for example r1_e0/1--r2_e0/1), i added a network entry
> to the ospf, to bring the adj. up, this was ok. I added a secondary ip address
> (in another subnet) to the interfaces in every router, and the corresponding
> network entry for the ospf. But the second ospf link didn't grow up... :(
>
> I made a topology like this:
>
>                 +---+           +---+
>                 |   |e0/1   e0/1|   |
>                 |   |----Ar0----|   |
>                 |   |           |   |
>                 | r1|sec     sec| r2|
>                 |   |----Ar1----|   |
>                 |   |           |   |
>                 +---+           +---+
>
> r1:
> The interface config:
> !
> interface Ethernet0/1
>  ip address 10.211.92.1 255.255.255.0 secondary
>  ip address 10.211.192.1 255.255.255.0
>  no ip directed-broadcast
>  ip ospf network point-to-point
>
> The ospf config:
> router ospf 1
>  network 10.211.92.0 0.0.0.255 area 1
>  network 10.211.192.0 0.0.0.255 area 0
> !
>
> On this router the ospf showed just the original interface with the original ip
> address...
>
> r1#show ip ospf interface
> Ethernet0/1 is up, line protocol is up
>   Internet Address 10.211.192.1/24, Area 0
>   Process ID 1, Router ID 10.211.192.1, Network Type POINT_TO_POINT, Cost: 10
>   Transmit Delay is 1 sec, State POINT_TO_POINT,
>   Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
>     Hello due in 00:00:00
>   Index 1/1, flood queue length 0
>   Next 0x0(0)/0x0(0)
>   Last flood scan length is 1, maximum is 2
>   Last flood scan time is 0 msec, maximum is 0 msec
>   Neighbor Count is 1, Adjacent neighbor count is 1
>     Adjacent with neighbor 10.211.192.8
>   Suppress hello for 0 neighbor(s)
>
>
> r2:
> Interface config:
> !
> interface Ethernet0/1
>  ip address 10.211.92.8 255.255.255.0 secondary
>  ip address 10.211.192.8 255.255.255.0
>  no ip directed-broadcast
>  ip ospf network point-to-point
>
> The ospf config:
> router ospf 1
>  network 10.211.92.0 0.0.0.255 area 1
>  network 10.211.192.0 0.0.0.255 area 0
> !
>
> On this router like the first, just the original ip address occur.
>
> r2#show ip ospf interface
> Ethernet0/1 is up, line protocol is up
>   Internet Address 10.211.192.8/24, Area 0
>   Process ID 1, Router ID 10.211.192.8, Network Type POINT_TO_POINT, Cost: 10
>   Transmit Delay is 1 sec, State POINT_TO_POINT,
>   Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
>     Hello due in 00:00:03
>   Index 1/1, flood queue length 0
>   Next 0x0(0)/0x0(0)
>   Last flood scan length is 1, maximum is 1
>   Last flood scan time is 0 msec, maximum is 0 msec
>   Neighbor Count is 1, Adjacent neighbor count is 1
>     Adjacent with neighbor 10.211.192.1
>   Suppress hello for 0 neighbor(s)
>
> Kozos volt a kovetkezo:
>
> The adj. was the same on each router.
>
> r1#show ip ospf neighbor
>
> Neighbor ID     Pri   State           Dead Time   Address         Interface
> 10.211.192.8      1   FULL/  -        00:00:32    10.211.192.8    Ethernet0/1
>
> The secondary ip address work, i can ping it. (for ex.: from r1 10.211.92.8)
>
> The experience with zebras was the same. They haven't seen the eth2:0 as ospf
> interface.
> show ip ospf interface  shows nothing about eth2:0.
>
> Hello packets were send just between the primary interfaces, so neighboring grow
> up just between them.
>
> Has anybody any idea, experience? Thanks a lot!
>
> Sincerely,
> Sandor Ecker
>
>


--
Acee