Configure interfaces and pbr for RHEL and its derivatives
Supported iterface types for network-scripts:

• ethernet (default)
• loopback

For RHEL8 use:

network:
  network_manager:
    iface:
      - conn_name: ens256
        ip4:
          - "100.127.2.2/29"
        routes4:
          - 0.0.0.0/0 100.127.2.6 table=200
          - 100.127.2.0/29 100.127.2.2 table=200
      - conn_name: dummy0
        type: dummy
        ip4:
          - "18.12.3.1/32"
        routing_rules4:
          - priority 5 from 18.12.3.1 table 200

For RHEL7 use:

network:
  network_scripts:
    iface:
      - name: ens256
        ip:
          - ipaddr: "100.127.2.2"
            prefix: "29"
      - name: lo
        type: loopback
        ip:
          - ipaddr: "18.12.3.1"
            prefix: "32"
        route:
          - default table 200 via 100.127.2.6
          - 100.127.2.0/29 table 200 via 100.127.2.2
        rule:
          - from 18.12.3.1 table 200
    pbr:
      table:
        - number: 200
          name: "prod"