Hi Experts,
How are you doing?
I need a small help to understand the actual behavior for BGP best path selection and advertised when Route reflector is considered.
My expectation was RR would advertise only the best path until add-path is enabled.
VM3 is my RR and receiving updated for prefix 9.9.9.9/32 from PEs 5.5.5.5 , 6.6.6.6, 7.7.7.7 .
VM4 is redundant RR 4.4.4.4
regress@vmx3# run show route protocol bgp 9.9.9.9/32
bgp.l3vpn.0: 8 destinations, 16 routes (8 active, 0 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both
5.5.5.5:3209:9.9.9.9/32
*[BGP/170] 10:31:57, localpref 100, from 5.5.5.5
AS path: 200 I, validation-state: unverified
> to 192.168.7.1 via ge-0/0/0.0, Push 17
[BGP/170] 10:12:58, localpref 100, from 4.4.4.4
AS path: 200 I, validation-state: unverified
> to 192.168.7.1 via ge-0/0/0.0, Push 17
6.6.6.6:3209:9.9.9.9/32
*[BGP/170] 10:39:13, localpref 200, from 6.6.6.6 >>>>>>>>> Localpref 200 is highest among others.
AS path: 200 I, validation-state: unverified
> to 192.168.8.1 via ge-0/0/1.0, Push 16
[BGP/170] 10:12:58, localpref 200, from 4.4.4.4.
AS path: 200 I, validation-state: unverified
> to 192.168.8.1 via ge-0/0/1.0, Push 16
7.7.7.7:3209:9.9.9.9/32
*[BGP/170] 10:23:12, localpref 100, from 7.7.7.7
AS path: 200 I, validation-state: unverified
> to 192.168.9.1 via ge-0/0/2.0, Push 16
[BGP/170] 10:12:58, localpref 100, from 4.4.4.4
AS path: 200 I, validation-state: unverified
> to 192.168.9.1 via ge-0/0/2.0, Push 16
When RR advertises the prefix - 9.9.9.9/32 to another end PEs.
regress@vmx3# run show route advertising-protocol bgp 1.1.1.1
bgp.l3vpn.0: 8 destinations, 16 routes (8 active, 0 holddown, 2 hidden)
Prefix Nexthop MED Lclpref AS path
2.2.2.2:6830:192.168.6.0/30
* 2.2.2.2 100 I
5.5.5.5:3209:9.9.9.9/32
* 5.5.5.5 100 3209 200 I
5.5.5.5:3209:192.168.14.0/30
* 5.5.5.5 100 3209 I
6.6.6.6:3209:9.9.9.9/32
* 6.6.6.6 200 3209 200 I
6.6.6.6:3209:192.168.15.0/30
* 6.6.6.6 200 3209 I
7.7.7.7:3209:9.9.9.9/32
* 7.7.7.7 100 3209 200 I
7.7.7.7:3209:192.168.16.0/30
* 7.7.7.7 100 3209 I
The question is why RR is adverting all the paths to other ends PE , expectation is RR should only advertise the best path until add-path is enabled.
What am I missing here ?
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Sujit Sahu
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