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buset1974
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BGP VPN4 problem on v6 & v7

Tue Mar 07, 2023 8:52 am

This topic how to produce the problem.

this the topology made with GNS3 lab.
topology-PE-CE.jpeg.jpg
CE advertise it’s loopback ip 192.168.0.100 to PE1 & PE2 with diffrent path length, hope that short bgp_path will be choosen as we can see in PE3

try this steps:

1. After CE rebooted everything looks fine. from PE3 we can see 192.168.0.100 with shorted path has been selected.
2. After that try to disable peer PE-1 from CE, then we can see from PE3 that 192.168.0.100 with longest path has been selected
3.Then try to enable again peer PE-1 from CE, then the problem happen, from PE3 we can still see 192.168.0.100 with longest path keep selected.
4.To make sure now you can disable peer PE-2 from CE, now from PE3 we can see 192.168.0.100 with shorted path has been selected.
5.Then try to enable peer PE-2 again from CE and from PE3 we can see 192.168.0.100 with shorted path still selected.

Problem happen exactly i explain at point 3 after prefix with longest path selected it wont come back to shorted path until we remove prefix with longest path from routing table.

I already try to replace PE with cisco or vyos problem point 3 did not happen. (see attachment for vyos configuration)

soon after peer PE-1 has been enabled, then we can see that prefix with shorted path selected.

i also found another problem, sometimes after disable peer from CE then enable it, sometime bgp stuck cannot established, until i have to enable/disable BGP on PE’s

hope everything clear maris, i already report this issues years.

please check and test this topology in yours labs.

thx
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mrz
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Re: BGP VPN4 problem on v6 & v7

Tue Mar 07, 2023 9:31 am

routes on PE received from CE and ones imported from vpnv4 are treated as routes from different instances, so bgp best path selection is not applied here.
v7 was initially made to work similarly to v6 until a proper solution is developed. This feature is currently being worked on, so you might see it already in one of the upcoming betas.
 
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mrz
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 10:15 am

Check v7.9beta4
 
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nichky
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 11:14 am

*) bgp - improved BGP VPN selection;

has RR been fixed?
 
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mrz
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 11:23 am

yes
 
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nichky
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 11:36 am

by using VRF?
 
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BartoszP
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 11:37 am

@mrz

Is it possible to write changelog as below to omit unnecessary questions
*) bgp - improved BGP VPN selection;
rr - fixed
bfd - not fixed
report [abc-def-ghi] fixed
report [abc-def-jkl] fixed
.....
 
buset1974
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Re: BGP VPN4 problem on v6 & v7

Fri Mar 24, 2023 12:49 pm

Check v7.9beta4
I have tested,
path selection in v7 vpn4 as i describe above now works

i appreciate


thank's maris

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