Re: BGP Tricky Question

Dear Andrew,
                   You are the man

Thanks Alot , it worked ,
backdoor is locally significant

Regards

On Wed, Apr 8, 2009 at 5:05 PM, ALL From_NJ <all.from.nj_at_gmail.com> wrote:

> This command is done on the receiving router since it is locally
> significant. Configure this on R3 since you want to alter the behavior on
> R3.
>
>
>
>
> On Wed, Apr 8, 2009 at 10:55 AM, Jason Alex <amr.ccie_at_gmail.com> wrote:
>
>> 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
>>>
>>
>>
>
>
> --
> Andrew Lee Lissitz
> all.from.nj_at_gmail.com

Blogs and organic groups at http://www.ccie.net
Received on Wed Apr 08 2009 - 17:12:33 ART