Zebra overwrites the nexthop ID for a static route

[christophefontaine]

Description

With FRR connected, if a user adds a static route from grcli, Zebra re-creates that same nexthop with a different ID:

grout# add nexthop address 192.168.210.3 iface cv0
grout# show nexthop
VRF  ID  TYPE  FAMILY  IP                         MAC                IFACE  STATE      FLAGS                      ORIGIN
0        L3    IPv6    fe80::b483:51ff:fe05:43ca  b4:83:51:05:43:ca  cv0    reachable  static local gateway link  link
0        L3    IPv6    fe80::b483:51ff:fe05:43cb  b4:83:51:05:43:cb  cv1    reachable  static local gateway link  link
0        L3    IPv4    192.168.210.1              b4:83:51:05:43:ca  cv0    reachable  static local gateway link  link
0    87  L3    IPv4    192.168.210.254            ?                  cv0    new                                   zebra
0    2   L3    IPv4    192.168.210.2              ?                  cv0    new        gateway                    zebra
0    1   L3    IPv4    192.168.210.3              ?                  cv0    new                                   user
0    89  L3    IPv4    192.168.210.6              ?                  cv0    new        gateway                    zebra
grout# add ip route 192.168.1.11/32 via id 1
grout# show ip route
VRF  DESTINATION       NEXT_HOP         ORIGIN        ID  NEXT_HOP_VRF
0    192.168.1.10/32   192.168.210.254  user          87  0
0    192.168.1.11/32   192.168.210.3    user          90  0
0    192.168.1.30/32   192.168.210.6    zebra_static  89  0
0    192.168.210.0/24  192.168.210.1    link              0
grout# show nexthop
VRF  ID  TYPE  FAMILY  IP                         MAC                IFACE  STATE      FLAGS                      ORIGIN
0        L3    IPv6    fe80::b483:51ff:fe05:43ca  b4:83:51:05:43:ca  cv0    reachable  static local gateway link  link
0        L3    IPv6    fe80::b483:51ff:fe05:43cb  b4:83:51:05:43:cb  cv1    reachable  static local gateway link  link
0        L3    IPv4    192.168.210.1              b4:83:51:05:43:ca  cv0    reachable  static local gateway link  link
0    87  L3    IPv4    192.168.210.254            ?                  cv0    new                                   zebra
0    2   L3    IPv4    192.168.210.2              ?                  cv0    new        gateway                    zebra
0    90  L3    IPv4    192.168.210.3              ?                  cv0    new                                   zebra
0    89  L3    IPv4    192.168.210.6              ?                  cv0    new        gateway                    zebra

In vtysh, we see both next hops though:

compute05.mgmt.foobar.space# show nexthop-group rib
ID: 1 (kernel)
     RefCnt: 1 Time to Deletion: 00:00:02
     Uptime: 00:03:18
     VRF: default(IPv4)
     Nexthop Count: 1
     Valid, Installed
     Interface Index: 257
           via 192.168.210.3, cv0 (vrf default), weight 1
ID: 90 (zebra)
     RefCnt: 2
     Uptime: 00:02:58
     VRF: default(IPv4)
     Nexthop Count: 1
     Valid, Installed
     Interface Index: 257
           via 192.168.210.3, cv0 (vrf default), weight 1

Version

grout v0.11.0-62-gc029279c-dirty (DPDK 24.11.1)