From: Ravi Singh (way2ccie@googlemail.com)
Date: Tue Feb 17 2009 - 22:51:42 ARST
Damn .. < slaps himself > . I seriously missed that one.
Thanks Hobbs.
Ravi
On Wed, Feb 18, 2009 at 12:45 AM, Hobbs <deadheadblues@gmail.com> wrote:
> What's the more preferred attribute?
>
>
> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml
>
> Step 10 vs 11....
>
> On Tue, Feb 17, 2009 at 5:33 PM, Ravi Singh <way2ccie@googlemail.com>wrote:
>
>> Hi Group,
>>
>> I think I might have to go back to basics here. Suppose R1 in AS-1 is
>> learning a prefix (2.0.0.0/8) from R2 in AS-2 and R-3 also in AS-2 is
>> connected to R1 & R2 both as in the diagram below
>>
>> R1 <----->R2
>> \ |
>> \ |
>> \ |
>> \ |
>> R3
>>
>> R1 forms an eBGP peer with R2 & R3 and R2 & R3 form iBGP amongst
>> themselves. R1 now receives the same prefix(2.0.0.0/8) from R3 as well
>> and
>> since everything else is same the comparison is made based on router-id &
>> R2
>> having a lower id (2.2.2.2) wins. Now, if on R1, I shut the BGP
>> relationship
>> towards R2 the only path will be from R3 as the best path. I turn the BGP
>> neighbor on again and R1 still shows the path from R3 as the best path
>> even
>> though R2 peering is up and R2 has a lower router-id.
>>
>> It stays this way untill I hard reset the BGP peering on R1(or R3). Even a
>> soft reset serves no good. My question is , is this the expected
>> behaviour
>> and if yes why so ? I mean shouldn't the protocol be intelligent enough to
>> recalculate its decisions on receiving prefixes with more preferred
>> attributes.
>>
>>
>> Thanks,
>> Ravi
>>
>>
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