Re: OSPF discontiguous areas

Correct. Once the information hits an ABR, nobody else has context
awareness to know it was one area 10 versus another area 10.

It just becomes incredibly confusing from a documentation standpoint. :)

HTH,

*Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,

JNCIE-M #153, JNCIS-ER, CISSP, et al.

JNCI-M, JNCI-ER

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Molomo wrote:
> Andy,
>
> We labbed it, it actually does work... it means they are different areas
> then.
>
> Thanks Andy...
>
>
>
>
> On Sat, Sep 5, 2009 at 2:22 PM, Andy Reid <ccie_at_reid.it> wrote:
>
>
>> Hi Molomo,
>>
>> Yes that will work just fine.
>> You can lab it yourself with just 3 routers:
>>
>> R2----area 1---R5---area 0 (loopback 0)---area 1-----R4
>>
>> I took a break out of the exciting world of multicast to lab it myself:
>>
>> R2:
>> interface Loopback0
>> ip address 2.2.2.2 255.0.0.0
>> !
>> interface Serial0/0
>> no ip address
>> encapsulation frame-relay
>> no dce-terminal-timing-enable
>> !
>> interface Serial0/0.25 point-to-point
>> ip address 10.1.25.2 255.255.255.0
>> ip pim sparse-mode
>> frame-relay interface-dlci 205
>> !
>> router ospf 1
>> log-adjacency-changes
>> network 0.0.0.0 255.255.255.255 area 1
>> end
>>
>> R5:
>> interface Loopback0
>> ip address 5.5.5.5 255.0.0.0
>> !
>> interface Serial0/0
>> no ip address
>> encapsulation frame-relay
>> !
>> interface Serial0/0.52 point-to-point
>> ip address 10.1.25.5 255.255.255.0
>> ip pim sparse-mode
>> frame-relay interface-dlci 502 !
>> !
>> interface Serial0/0.54 point-to-point
>> ip address 10.1.45.5 255.255.255.0
>> ip pim sparse-mode
>> frame-relay interface-dlci 504 !
>> router ospf 1
>> log-adjacency-changes
>> network 5.5.5.5 0.0.0.0 area 0
>> network 10.0.0.0 0.255.255.255 area 1
>> end
>>
>> R4:
>> interface Loopback0
>> ip address 4.4.4.4 255.0.0.0
>> !
>> interface Serial0/0
>> no ip address
>> encapsulation frame-relay
>> no dce-terminal-timing-enable
>> !
>> interface Serial0/0.45 point-to-point
>> ip address 10.1.45.4 255.255.255.0
>> ip pim sparse-mode
>> frame-relay interface-dlci 405 !
>> router ospf 1
>> log-adjacency-changes
>> network 0.0.0.0 255.255.255.255 area 1
>> end
>>
>> The end result is area 0 on a stick :)
>>
>> R5#show ip os ne
>> Neighbor ID Pri State Dead Time Address Interface
>> 4.4.4.4 0 FULL/ - 00:00:32 10.1.45.4
>> Serial0/0.54
>> 2.2.2.2 0 FULL/ - 00:00:37 10.1.25.2
>> Serial0/0.52
>>
>> R5#show ip route ospf
>> 2.0.0.0/32 is subnetted, 1 subnets
>> O 2.2.2.2 [110/65] via 10.1.25.2, 00:07:09, Serial0/0.52
>> 4.0.0.0/32 is subnetted, 1 subnets
>> O 4.4.4.4 [110/65] via 10.1.45.4, 00:07:09, Serial0/0.54
>>
>>
>> R2#show ip route ospf
>> 4.0.0.0/32 is subnetted, 1 subnets
>> O 4.4.4.4 [110/129] via 10.1.25.5, 00:07:38, Serial0/0.25
>> 5.0.0.0/32 is subnetted, 1 subnets
>> O IA 5.5.5.5 [110/65] via 10.1.25.5, 00:07:38, Serial0/0.25
>> 10.0.0.0/24 is subnetted, 2 subnets
>> O 10.1.45.0 [110/128] via 10.1.25.5, 00:07:38, Serial0/0.25
>>
>> R2#ping 4.4.4.4
>> Type escape sequence to abort.
>> Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
>> !!!!!
>> Success rate is 100 percent (5/5), round-trip min/avg/max = 112/127/176 ms
>>
>> R4#show ip route ospf
>> 2.0.0.0/32 is subnetted, 1 subnets
>> O 2.2.2.2 [110/129] via 10.1.45.5, 00:08:18, Serial0/0.45
>> 5.0.0.0/32 is subnetted, 1 subnets
>> O IA 5.5.5.5 [110/65] via 10.1.45.5, 00:08:18, Serial0/0.45
>> 10.0.0.0/24 is subnetted, 2 subnets
>> O 10.1.25.0 [110/128] via 10.1.45.5, 00:08:18, Serial0/0.45
>>
>> Also check out this Cisco link:
>> http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094704.shtml
>>
>> regards Andy
>>
>>
>> Molomo wrote:
>>
>>
>>> Experts,
>>>
>>> I would like to know if the setup below is valid, and whether R1 & R4 will
>>> be able to reach each other.
>>>
>>>
>>> R1---area 1-----R2---area 0-----R3----area 1-----R4
>>>
>>>
>>> Regards,
>>> Molomo
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
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>>>
>
>
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>
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Received on Sat Sep 05 2009 - 12:55:22 ART