bgp: removing daemon and re-adding it to config does not clear "l2vpn evpn" config

[c-po]

Description

When stopping no router bgp ASN and restarting router bgp ASN the bgpd configuration will keep parts which are not cleared and will survive.

Version

# show version
FRRouting 10.1.1 (LR1.wue3) on Linux(6.6.56-vyos).
Copyright 1996-2005 Kunihiro Ishiguro, et al.

$ git describe
frr-10.1.1-103-ga5755342e

a5755342e

How to reproduce

Configure BGP process

!
router bgp 100
 no bgp ebgp-requires-policy
 no bgp default ipv4-unicast
 no bgp network import-check
 !
 address-family l2vpn evpn
  ead-es-frag evi-limit 1000
  disable-ead-evi-rx
  disable-ead-evi-tx
 exit-address-family
exit
!

Remove bgpd configuration

!
no router bgp 100
!

Re-enable bgpd configuration

!
router bgp 100
!

Expected behavior

!
router bgp 100
exit
!

Actual behavior

router bgp 100
 !
 address-family l2vpn evpn
  ead-es-frag evi-limit 1000
  disable-ead-evi-rx
  disable-ead-evi-tx
 exit-address-family
exit
!

Additional context

No response

Checklist

• I have searched the open issues for this bug.
• I have not included sensitive information in this report.

[chiragshah6]

I have tried similar steps and do not see the issue, upon re creating bgp instance, evpn address-family didn't come back.

bharat# show running-config 
Building configuration...

Current configuration:
!
frr version 10.3-dev
frr defaults traditional
hostname bharat
log file /var/log/frr/pimd.log
log syslog
log timestamp precision 6
no ip forwarding
no ipv6 forwarding
service integrated-vtysh-config
!
ip prefix-list 10.225.4.66-pl-ipv4 seq 5 permit 10.225.4.36/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 10 permit 10.225.4.0/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 15 permit 10.225.4.2/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 20 permit 10.225.4.3/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 25 permit 10.225.4.35/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 30 permit 10.225.4.34/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 35 permit 10.225.4.33/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 40 permit 10.225.4.32/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 45 deny any
!
vrf vrf_blue
exit-vrf
!
router bgp 100
 no bgp ebgp-requires-policy
 no bgp default ipv4-unicast
 no bgp network import-check
 !
 address-family l2vpn evpn
  ead-es-frag evi-limit 1000
  disable-ead-evi-rx
  disable-ead-evi-tx
 exit-address-family
exit
!
end
bharat# config t
bharat(config)# no router bgp 100 


bharat(config)# do show running-config bgpd 
Building configuration...

Current configuration:
!
frr version 10.3-dev
frr defaults traditional

service integrated-vtysh-config
!
ip prefix-list 10.225.4.66-pl-ipv4 seq 5 permit 10.225.4.36/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 10 permit 10.225.4.0/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 15 permit 10.225.4.2/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 20 permit 10.225.4.3/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 25 permit 10.225.4.35/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 30 permit 10.225.4.34/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 35 permit 10.225.4.33/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 40 permit 10.225.4.32/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 45 deny any
!
vrf vrf_blue
exit-vrf
!
end
bharat(config)# router bgp 100
bharat(config-router)# do show running-config bgpd 
Building configuration...

Current configuration:
!
frr version 10.3-dev
frr defaults traditional

service integrated-vtysh-config
!
ip prefix-list 10.225.4.66-pl-ipv4 seq 5 permit 10.225.4.36/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 10 permit 10.225.4.0/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 15 permit 10.225.4.2/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 20 permit 10.225.4.3/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 25 permit 10.225.4.35/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 30 permit 10.225.4.34/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 35 permit 10.225.4.33/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 40 permit 10.225.4.32/32
ip prefix-list 10.225.4.66-pl-ipv4 seq 45 deny any
!
vrf vrf_blue
exit-vrf
!
router bgp 100
 !
 address-family l2vpn evpn
  ead-es-frag evi-limit 1000
  disable-ead-evi-rx
  disable-ead-evi-tx
 exit-address-family
exit
!
end
bharat(config-router)# 

[c-po]

I have tried similar steps and do not see the issue, upon re creating bgp instance, evpn address-family didn't come back.

Hi @chiragshah6,

in your output provided you re-enabled BGP:

bharat(config)# router bgp 100

and during config show EVPN address family re-appeaed, too

bharat(config-router)# do show running-config bgpd 
...
router bgp 100
 !
 address-family l2vpn evpn
  ead-es-frag evi-limit 1000
  disable-ead-evi-rx
  disable-ead-evi-tx
 exit-address-family
exit
...

[ykholod]

To add more, we do not clean distance for address family on bgp router reset:
!
router bgp 100
!
address-family ipv4 unicast
distance 100 10.0.0.0/24
exit-address-family
exit
!