From: Hobbs (deadheadblues@gmail.com)
Date: Tue Feb 17 2009 - 22:45:42 ARST
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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