kea/doc/examples/kea4/shared-network.json

// This is an example configuration file for DHCPv4 server in Kea.
// It demonstrates an advanced feature called shared network. Typically, for
// each physical link there is one IPv4 subnet that the server is expected
// to manage. However, in some cases there is a need to configure more subnets
// in the same physical location. The most common use case is an existing
// subnet that grew past its original assumptions and ran out of addresses,
// so the sysadmin needs to add another subnet on top of existing one.
{
    "Dhcp4": {

        // As with any other configuration, you need to tell Kea the interface
        // names, so it would listen to incoming traffic.
        "interfaces-config": {
            "interfaces": [ "ethX" ]
        },

        // You also need to tell where to store lease information.
        // memfile is the backend that is easiest to set up.
        "lease-database": {
            "type": "memfile",
            "lfc-interval": 3600
        },

        // The shared networks definition starts here. shared-networks can
        // contain a list of shared networks. There are many parameters
        // that can be specified here, so this example may be overwhelming
        // at first, but the only mandatory parameter for each shared
        // network is name. It must be unique. Typically, each shared
        // network also needs to have at least two subnets to be functional,
        // but if you really want to, you can define a degraded shared
        // network that has 1 or even 0 subnets. This may come in handy
        // when migrating between regular subnets and shared networks
        // or when debugging a problem. It is not recommended to use
        // 1 subnet per shared network, as there is extra processing
        // overhead for shared networks.
        "shared-networks": [
        {
            // Name of the shared network. It may be an arbitrary string
            // and it must be unique among all shared networks.
            "name": "frog",

            // You may specify interface name if the shared network is
            // reachable directly from the server.
            "interface": "eth1",

            // You can specify many parameters that are allowed in subnet scope
            // here. It's useful to put them here if they apply to all subnets
            // in this shared network. It's likely that the most common
            // parameter here will be option values defined with option-data.
            "match-client-id": false,
            "option-data": [ ],
            "rebind-timer": 150,

            // If all the traffic coming from that shared network is reachable
            // via relay and that relay always use the same IP address, you
            // can specify that relay address here. Since this example shows
            // a shared network reachable directly, we put 0.0.0.0 here.
            // It would be better to skip the relay scope altogether, but
            // it was left here for demonstration purposes.
            "relay": {
                "ip-address": "0.0.0.0"
            },

            // Timer values can be overridden here.
            "renew-timer": 100,
            "reservation-mode": "all",

            // This starts a list of subnets allowed in this shared network.
            // In our example, there are two subnets.
            "subnet4": [
                {
                    "id": 1,
                    "match-client-id": true,
                    "next-server": "0.0.0.0",
                    "option-data": [ ],
                    "pools": [ ],
                    "rebind-timer": 20,

                    // You can override the value inherited from shared-network
                    // here if your relay uses different IP addresses for
                    // each subnet.
                    "relay": {
                        "ip-address": "0.0.0.0"
                    },
                    "renew-timer": 10,
                    "reservation-mode": "all",
                    "subnet": "10.0.0.0/8",
                    "valid-lifetime": 30
                },
                {
                    "id": 2,
                    "match-client-id": true,
                    "next-server": "0.0.0.0",
                    "option-data": [ ],
                    "pools": [ ],
                    "rebind-timer": 20,
                    "renew-timer": 10,
                    "reservation-mode": "all",
                    "subnet": "192.0.2.0/24",
                    "valid-lifetime": 30
                }
            ],
            "valid-lifetime": 200
        } ], // end of shared-networks

        // It is likely that in your network you'll have a mix of regular,
        // "plain" subnets and shared networks. It is perfectly valid to mix
        // them in the same config file.
        //
        // This is regular subnet. It's not part of any shared-network.
        "subnet4": [
            {
                "pools": [ { "pool":  "192.0.3.1 - 192.0.3.200" } ],
                "subnet": "192.0.3.0/24",
                "interface": "eth0",
                "id": 3
            }
        ]

    } // end of Dhcp4
}