================ Network Planning ================ A clustered resource depends on a cluster network. This network can be either persistent (it is always "up" even after provisioning) or temporary, only used for provisioning and/or out of band system control and management (e.g., IPMI). The cluster network must be dedicated to the cluster because Warewulf uses network services (particularly DHCP) which may conflict with services on another mixed-use network. A dedicated cluster network is also important for security, as the cluster network often has an implicit level of trust associated with it. The Warewulf server is often "dual homed," meaning that it has separate network interfaces connected to each of the cluster network and an external network. But it is also possible for the cluster network to be routable from other, more general-purpose networks. Many clusters have more than one internal network. This is common for performance critical HPC clusters that implement a high speed and low latency network like InfiniBand. In this case, this network is used for high speed data transfers for inter-process communication between compute nodes and file system IO. Warewulf will need to be configured to use the private cluster management network. Warewulf will use this network for booting the nodes over PXE. There are three network protocols used to accomplish this DHCP/BOOT, TFTP, and HTTP on port ``9873``. Warewulf will use the operating system's provided version of DHCP (ISC-DHCP) and TFTP for the PXE bootstrap to iPXE, and then iPXE will use Warewulf's internal HTTP services to transfer the larger files for provisioning. Addressing ========== The addressing scheme of your private cluster network is 100% up to the system integrator, but for large clusters, many organizations like to organize the address allocations. Below is a recommended IP addressing scheme which we will use for the rest of this document. * ``10.0.0.1``: Private network address IP * ``255.255.252.0``: Private network subnet mask (``10.0.0.0/22``) Here is an example of how the cluster's address can be divided for a 255 node cluster: * ``10.0.0.1 - 10.0.0.255``: Cluster infrastructure including this host, schedulers, file systems, routers, switches, etc. * ``10.0.1.1 - 10.0.1.255``: DHCP range for booting nodes * ``10.0.2.1 - 10.0.2.255``: Static node addresses * ``10.0.3.1 - 10.0.3.255``: IPMI and/or out of band addresses for the compute nodes Multiple networks ================= It is possible to configure several networks not just for the nodes but also for the management of ``dhcpd`` and ``tftp``. There are two ways to achieve this: * Add the networks to the templates of ``dhcpd`` and/or the ``dnsmasq`` template directly. * Add the networks to a dummy node and change the templates of ``dhcp`` and ``dnsmasq`` accordingly. The first method is relatively trivial. The second method is described below. As the first step, add the dummy node. .. code-block:: shell wwctl node add deliverynet Add the delivery networks to this node. .. code-block:: shell wwctl node set \ --ipaddr 10.0.20.250 \ --netmask 255.255.255.0 \ --netname deliver1 \ --nettagadd network=10.0.20.0,dynstart=10.10.20.10,dynend=10.10.20.50 \ deliverynet wwctl node set \ --ipaddr 10.0.30.250 \ --netmask 255.255.255.0 \ --netname deliver2 \ --nettagadd network=10.0.30.0,dynstart=10.10.30.10,dynend=10.10.30.50 \ deliverynet The IP address is used as the network address of the host in the delivery network and an additional tag is used for the definition of the network itself and the dynamic dhcp range. You can check the result with ``wwctl node list``. .. code-block:: console # wwctl node list -a deliverynet NODE FIELD PROFILE VALUE deliverynet Id -- deliverynet deliverynet Comment default This profile is automatically included for each node deliverynet ImageName default leap15.5 deliverynet Ipxe -- (default) deliverynet RuntimeOverlay -- (hosts,ssh.authorized_keys) deliverynet SystemOverlay -- (wwinit,wwclient,hostname,ssh.host_keys,systemd.netname,NetworkManager) deliverynet Root -- (initramfs) deliverynet Init -- (/sbin/init) deliverynet Kernel.Args -- (quiet crashkernel=no net.ifnames=1) deliverynet Profiles -- default deliverynet PrimaryNetDev -- (deliver1) deliverynet NetDevs[deliver2].Type -- (ethernet) deliverynet NetDevs[deliver2].OnBoot -- (true) deliverynet NetDevs[deliver2].Ipaddr -- 10.0.30.250 deliverynet NetDevs[deliver2].Netmask -- 255.255.255.0 deliverynet NetDevs[deliver2].Tags[dynend] -- 10.10.30.50 deliverynet NetDevs[deliver2].Tags[dynstart] -- 10.10.30.10 deliverynet NetDevs[deliver2].Tags[network] -- 10.0.30.0 deliverynet NetDevs[deliver1].Type -- (ethernet) deliverynet NetDevs[deliver1].OnBoot -- (true) deliverynet NetDevs[deliver1].Ipaddr -- 10.0.20.250 deliverynet NetDevs[deliver1].Netmask -- 255.255.255.0 deliverynet NetDevs[deliver1].Primary -- (true) deliverynet NetDevs[deliver1].Tags[network] -- 10.0.20.0 deliverynet NetDevs[deliver1].Tags[dynend] -- 10.10.20.50 deliverynet NetDevs[deliver1].Tags[dynstart] -- 10.10.20.10 Now the templates of ``dhcpd`` and/or ``dnsmasq`` must be modified. .. code-block:: shell wwctl overlay edit host etc/dhcpd.conf.ww wwctl overlay edit host etc/dnsmasq.d/ww4-hosts.ww For the ``dhcp`` template you should add following lines .. code-block:: {{/* multiple networks */}} {{- range $node := $.AllNodes}} {{- if eq $node.Id.Get "deliverynet" }} {{- range $netname, $netdev := $node.NetDevs}} # network {{ $netname }} subnet {{$netdev.Tags.network.Get}} netmask {{$netdev.Netmask.Get}} { max-lease-time 120; range {{$netdev.Tags.dynstart.Get}} {{$netdev.Tags.dynend.Get}}; next-server {{$netdev.Ipaddr.Get}}; } {{- end }} {{- end }} {{- end }} and for the ``dnsmasq`` the following lines should be added .. code-block:: {{/* multiple networks */}} {{- range $node := $.AllNodes}} {{- if eq $node.Id.Get "deliverynet" }} {{- range $netname, $netdev := $node.NetDevs}} # network {{ $netname }} dhcp-range={{$netdev.Tags.dynstart.Get}},{{$netdev.Tags.dynend.Get}},{{$netdev.Netmask.Get}},6h {{- end }} {{- end }} {{- end }} Note that the ``{{- if eq $node.Id.Get "deliverynet" }}`` is used to identify the dummy host which carries the network information.