Re: IEExpert Vol 2 version 4.1 task 4.11

See also:-
http://www.groupstudy.com/archives/ccielab/200806/msg00039.html

Paul.

Paul Cosgrove wrote:
> Hi Abdul Jaleel,
>
> I think I remember this one. It is required to prevent a loop. If a
> rip route is advertised into OSPF, it can later be redistributed into
> eigrp, before being redistributed back into OSPF. If that happens
> then SW1 will receive the route back with a OSPF AD. It would then
> prefer that over the RIP route which was the original source.
>
> This can happen despite EIGRP external routes having a higher AD than
> OSPF, an example would be if the OSPF interface on R4 failed. R4
> would still learn the route via EIGRP and, since it also has an OSPF
> loopback, it would still insert it into OSPF. When full connectivity
> was restored, you would then have SW1 and R4, both with the same
> external OSPF route. So you need to make sure that SW1 does not use
> the external route it learns from R4, over the locally redistributed
> one it creates.
>
> Paul.
>
>
> kaniyath minha wrote:
>> Dear
>>
>> While redistributing RIP into OSPF and vise versa on Rack1SW1, why the
>> distance 109 command is used under router rip command.
>>
>> There is no explanation on SG and question is not specifying anything
>> for
>> changing this.
>>
>>
>> Below shows the question and answer which is showed in SG
>> *
>> Question *
>>
>> 4.11. IGP Redistribution
>>  Redistribute between RIP and OSPF on SW1.
>>  Redistribute between OSPF and EIGRP on R2, R3, and R4.
>>  Ensure that full reachability is maintained throughout the IGP domain
>> when the Frame Relay circuit between R3 and R5 is down.
>>
>> *Answer in SG*
>>
>> Task 4.11
>> SW1:
>> router ospf 1
>> redistribute rip subnets
>> network 132.1.17.7 0.0.0.0 area 17
>> !
>> router rip
>> redistribute ospf 1 metric 1
>> distance 109 *(Why this command required in this particular scenario)
>>
>> *Thanks and Regards*
>> *Abdul Jaleel Kaniyath*
>> *
>>
>>
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Received on Wed May 06 2009 - 12:53:12 ART