Re: BGP Tricky Question

Dear Andrew,
                  Thanks for you info
But i have configured the backdoor option on R1 , it has no effect
I think if the Loopback is on R2 , i think it will works

Correct me if i am wrong

Regards
Amr

On Wed, Apr 8, 2009 at 4:51 PM, ALL From_NJ <all.from.nj_at_gmail.com> wrote:

> Hello Jason,
>
> When you are learning a route via eBGP and and OSPF, the ADs are 20 and
> 110. 20 is better than 110 ...
>
> You can not change the AD ... in this case, you need to tell BGP that the
> IGP route should be preferred.
>
> This link should assist (watch for the ugly word wrap):
>
>
> http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp4.html#wp1012431
>
> From this link:
> *Usage Guidelines ***
>
> *A backdoor network is assigned an administrative distance of 200. The
> objective is to make Interior Gateway Protocol (IGP) learned routes
> preferred. A backdoor network is treated as a local network, except that it
> is not advertised. A network that is marked as a back door is not sourced by
> the local router, but should be learned from external neighbors. The BGP
> best path selection algorithm does not change when a network is configured
> as a back door*
> This was one of those topics I had to lab up to learn. Once I labbed it,
> it made sense to me. HTH and have a great day,
>
> Andrew Lee Lissitz
>
>
>
>
> On Wed, Apr 8, 2009 at 10:30 AM, Jason Alex <amr.ccie_at_gmail.com> wrote:
>
>> Dear All,
>> The Setup is as follows
>>
>> R1(s0/0)-----------OSPF Area 0-----------(S0/0)R2(fa0/0)---------OSPF Area
>> 1---------------(fa0/0)R3
>>
>> R1 is in BGP AS 10
>> R2 is in BGP AS 10
>> R3 is in BGP AS 20
>>
>> R2 peers with R1 & R3
>>
>> *The Question Says that:*
>> Configure Loopback 40 on R1 (40.40.40.40/32) and advertise it to R2 via
>> both
>> OSPF & BGP
>> Make sure that R3 Sees Loopback 40 of R1 as O IA route with AD 110 , and
>> the
>> route must also appears on R3's BGP table
>> You must not use the distance command
>>
>> Any ideas how to solve this question without using the distance command
>>
>> Regards
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>>
>>
>>
>>
>>
>>
>>
>
>
> --
> Andrew Lee Lissitz
> all.from.nj_at_gmail.com

Blogs and organic groups at http://www.ccie.net
Received on Wed Apr 08 2009 - 16:55:15 ART