Stale BGP advertised routes are observed

[pravinbodake]

I have configured the two BGP neighbors & announcement the networks. I have deleted neighbor, added again with same config & removed the announced network from configuration. But still I was able to see announced network prefixes for neighbors.

Daemons:

frr      13190     1  0  80   0 - 114023 poll_s 12:04 ?       00:00:01 /usr/lib/frr/zebra -d -A 127.0.0.1 -s 90000000 -F datacenter
frr      13197     1  0  80   0 -  2155 poll_s 12:04 ?        00:00:00 /usr/lib/frr/staticd -d -A 127.0.0.1 -F datacenter
frr      13205     1  0  80   0 - 45990 poll_s 12:04 ?        00:02:08 /usr/lib/frr/bgpd -d -A 127.0.0.1 -F datacenter

Current configuration:

frr defaults datacenter
log syslog
no ip forwarding
service integrated-vtysh-config
!
router bgp 65110
 bgp router-id 10.16.163.110
 no bgp network import-check
 neighbor 10.2.1.1 remote-as 65111
 neighbor 10.2.1.1 description "peer 1"
 neighbor 10.2.1.1 solo
 neighbor 10.2.1.1 advertisement-interval 1
 neighbor 10.2.1.1 timers 3 9
 neighbor 10.2.1.1 timers connect 20
 neighbor 10.2.2.1 remote-as 65111
 neighbor 10.2.2.1 description "peer 2"
 neighbor 10.2.2.1 solo
 neighbor 10.2.2.1 advertisement-interval 1
 neighbor 10.2.2.1 timers 3 9
 neighbor 10.2.2.1 timers connect 20
 address-family ipv4 unicast
  neighbor 10.2.1.1 soft-reconfiguration inbound
  neighbor 10.2.1.1 route-map 1660669482445015312 in
  neighbor 10.2.1.1 route-map 1660669482414014712 out
  neighbor 10.2.2.1 soft-reconfiguration inbound
  neighbor 10.2.2.1 route-map 1660669482719018312 in
  neighbor 10.2.2.1 route-map 1660669482687017712 out
route-map 1660669482445015312 permit 10
 set local-preference 100
exit
!
route-map 1660669482414014712 permit 99
 match as-path 1660669482383014112
 match ip address prefix-list 1659087428747022312
 set as-path prepend 65110 65110 65110 65110
exit
!
route-map 1660669482414014712 permit 100
 match as-path 1660669482383014112
 match ip address prefix-list 1659087428786023312
 set as-path prepend 65110 65110 65110 65110
 set community no-advertise
exit
route-map 1660669482719018312 permit 10
 set local-preference 100
exit
!
route-map 1660669482687017712 permit 99
 match as-path 1660669482654017112
 match ip address prefix-list 1659087428747022312
 set as-path prepend 65110 65110 65110 65110
exit
!
route-map 1660669482687017712 permit 100
 match as-path 1660669482654017112
 match ip address prefix-list 1659087428786023312
 set as-path prepend 65110 65110 65110 65110
 set community no-advertise
exit

BGP Peer summary & BGP peer advertised-routes

IPv4 Unicast Summary (VRF default):
BGP router identifier 10.16.163.110, local AS number 65110 vrf-id 0
BGP table version 348
RIB entries 90, using 16 KiB of memory
Peers 4, using 2892 KiB of memory

Neighbor        V         AS   MsgRcvd   MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd   PfxSnt Desc
10.2.1.1        4      65111       368       352        0    0    0 00:17:29           42        8 "core peer 166066948
10.2.2.1        4      65111       369       352        0    0    0 00:17:29           42        8 "core peer 166066948
10.2.3.1        4      65112      2445      2402        0    0    0 02:00:01           22        0 "edge peer 166067026
10.2.4.1        4      65112      2446      2401        0    0    0 02:00:00           25        0 "edge peer 166067026

Total number of neighbors 4

# show ip bgp neighbors 10.2.2.1 advertised-routes
BGP table version is 348, local router ID is 10.16.163.110, vrf id 0
Default local pref 100, local AS 65110
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.2.52.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.52.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.53.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.53.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.54.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.54.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.56.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.56.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i

Total number of prefixes 8

#show ip bgp neighbors 10.2.1.1 advertised-routes'
BGP table version is 348, local router ID is 10.16.163.110, vrf id 0
Default local pref 100, local AS 65110
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.2.52.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.52.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.53.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.53.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.54.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.54.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.56.0/25     0.0.0.0                  0         32768 65110 65110 65110 65110 i
*> 10.2.56.128/25   0.0.0.0                  0         32768 65110 65110 65110 65110 i

Total number of prefixes 8

Expected behavior:
BGP should not advertise prefixes to neighbor if network prefix not announced or not configured in router.

Screenshots
None

Versions
Linux Kernel 5.4.27-yocto-standard