Re: BGP best path

Hi. This refers to if you have for example:
 network 2.2.2.2 mask 255.255.255.255
 aggregate-address 2.2.2.2 255.255.255.255

then network one will be preferred.
Here is an example (i had to aggregate to something other than /32 to get
the route into BGP TABLE)

R2#sh ip bgp 2.2.2.0
BGP routing table entry for 2.2.2.0/24, version 6
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Flag: 0x820
  Advertised to update-groups:
     1 2
  Local, (aggregated by 20 2.2.2.2)
    0.0.0.0 from 0.0.0.0 (2.2.2.2)
      Origin IGP, localpref 100, weight 32768, valid, aggregated, local,
atomic-aggregate, best
R2#sh ip bgp 2.2.2.2
BGP routing table entry for 2.2.2.2/32, version 3
Paths: (1 available, best #1, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1 2
  Local
    0.0.0.0 from 0.0.0.0 (2.2.2.2)
      Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced,
local, best

As you can see:
locally aggregated PAs: Origin IGP, localpref 100, weight 32768, valid,
aggregated, local, atomic-aggregate, best
locally originated PAs: Origin IGP, metric 0, localpref 100, weight 32768,
valid, sourced, local, best

The difference is where originated states "sourced", while aggregated states
"aggregated".
So if you'd have the case where two refer to the same network, bgp would
choose "sourced" before "aggregated"

On Wed, Jul 8, 2009 at 7:37 AM, jack daniels <jckdaniels12_at_gmail.com> wrote:

> Hi All,
>
> please advise in bgp best path selection step 3 says
>
> Prefer locally originated route
> A locally sourced path is better than a locally aggregated path?????
>
> what doe it mean ?
>
> Thanks and Regards
>
>
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