Setup BIRD with BGP on loopback or dummy interface

For RHEL8 use 'nm' for NetworkManager and dummy iface for BGP IPs
For RHEL7 use 'network-scripts' for network-scripts and lo iface for BGP IPs

 network: "nm"
 network_nm_iface: "dummy0"

Use null for MTU auto

 network_nm_iface_mtu: null

BIRD config example:

bird:
  bgp:
    common:
      storage04.s3.msk2.example.com:
        routerid: 10.101.42.14
      storage05.s3.msk2.example.com:
        routerid: 10.101.42.15
      storage06.s3.msk2.example.com:
        routerid: 10.101.42.16
      storage07.s3.msk2.example.com:
        routerid: 10.101.42.17
    static:
      - name: STATIC1
        networks:
          storage04.s3.msk2.example.com:
            - ip: "10.110.42.1"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
            - ip: "10.110.42.21"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
          storage05.s3.msk2.example.com:
            - ip: "10.110.42.1"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
            - ip: "10.110.42.21"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
          storage06.s3.msk2.example.com:
            - ip: "10.110.42.1"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
            - ip: "10.110.42.21"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
          storage07.s3.msk2.example.com:
            - ip: "10.110.42.1"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
            - ip: "10.110.42.21"
              mask: "255.255.255.255"
              mask_dash: "32"
              bgp_local_pref: "100"
    bgp:
      - name: SW06
        remote_asnum: 4200200000
        local_asnum: 4200200000
        confederation: 209684
        remote_addr: "10.127.2.6"
        export:
          - STATIC1
      - name: SW10
        remote_asnum: 4200200000
        local_asnum: 4200200000
        confederation: 209684
        remote_addr: "10.127.2.10"
        export:
          - STATIC1