metal-core

metal-core dynamically reconfigures switches based on the state held in the metal-api. Therefore, it must run on every leaf switch and have control over the configuration files for network interfaces and the routing suite (/etc/frr/frr.config) of the switches.

In the PXE-boot process of machines metal-core will act as a proxy between API-requests issued by pixiecore and the metal-api. The metal-api will answer with a mini OS (see metal-hammer and kernel).

Besides that, it ensures the proper boot order (IPMI) and monitors their liveliness with LLDP).

Build

Ensure you have libpcap-dev installed.

make

Interface Naming on SONiC Switches

On SONiC switches, there are different naming schemas for interfaces. For example, the first port could be named Ethernet0, or it could be Eth1/1 or something similar. Additionally, a port can have an alias, which may be the same as its name or it may follow a different naming schema. If the port is named Ethernet0 the alias could be Eth1/1(Port1). But it could also be the other way round. The defaults for the naming schemas differ across distributions.

These differences wouldn't cause any problems if it weren't for LLDP. An LLDP message carries two fields to identify the port, portidsubtype and portdescription. Depending on the distribution portidsubtype will be either the port's name or its alias and portdescription, usually, will be the other of the two. So the metal-core registers its ports at the metal-api which stores the names as V1SwitchNic.Name and aliases as V1SwitchNic.Identifier. At the same time, when a machine registers at the metal-api it reports its LLDP neighbors and identifies the neighbors' ports by portidsubtype and portdescription. When the metal-api attempts to match the machine's neighbors with the neighboring switches' ports it compares each neighboring switch's portidsubtype with all of its Nics' .Identifier fields. But this only works if the port's alias is identical to its portidsubtype which, as stated above, is not always the case.

While it is possible to configure portidsubtype and portdescription via lldpcli, this configuration is not persisted. A simple change of the MTU will restore the defaults. So this is not a viable solution.

To accommodate all of the possible combinations, there is an InterfaceNamingSchema option. This option has nothing to do with SONiC's interface-naming. It simply tells metal-core how it should report its ports to the metal-api. It allows the following values.

• default: V1SwitchNic.Name is the interface name; V1SwitchNic.Identifier is the interface alias
• swap: name and alias get swapped
• name: both V1SwitchNic.Name and V1SwitchNic.Identifier will be the interface name
• alias: both V1SwitchNic.Name and V1SwitchNic.Identifier will be the interface alias

To determine which of these suits your setup compare the port aliases with the LLDP configuration for portidsubtype. If they match the correct value for InterfaceNamingSchema is default. If not, check if portdescription matches the alias and portidsubtype matches the name. In that case you can use swap. If you need to have both of the fields to have the same value, use either name or alias.