In oVirt 4.2 we have introduced support for the Link Layer Discovery Protocol (LLDP).
It is used by network devices for advertising the identity and capabilities to
neighbors on a LAN. The information gathered by the protocol can be used for better
network configuration. Learn more about LLDP.

Why do you need LLDP?

When adding a host into oVirt cluster, the network administrator usually needs to attach
various networks to it. However, a modern host can have multiple interfaces, each
with its non-descriptive name.


In the screenshot below, taken from the Administration Portal, a network administrator has to know
to which interface to attach the network named m2 with VLAN_ID 162. Should it be interface
enp4s0, ens2f0 or even ens2f1? With oVirt 4.2, the administrator can hover over enp4s0
and see that this interface is connected to peer switch rack01-sw03-lab4, and learn that this
peer switch does not support VLAN 162 on this interface. By looking at every interface, the
administrator can choose which interface is the right option for networkm2.


A similar situation arises with the configuration of mode 4 bonding (LACP). Configurating LACP
usually starts with network administrator defining a port group on their switch. These ports are
are physically connected to interfaces in a hypervisor. But to which of the many interfaces that
this hypervisor may have?

For example, when creatingbond0 (See screenshot below), it is important to pick interfaces that
are connected to the same switch, and that these ports belong to the same port group. Often, an
oVirt administrator might choose the wrong interfaces, and end up with badly configured bonds.

With LLDP information, this can easily be avoided. The administrator can tell which is the peer of
each interface, and to which port group it is connected. For example, enp4s0 is
connected to port GigabitEthernet0/9 and enp6s0 is connected to port
GigabitEthernet0/10 on the same peer switch named rack03-sw02-lab4.



The final screenshot (below) shows the information available to the administrator via
the Administration Portal. This includes System name, Port description, Aggregation information, MTU, VLAN IDs and names.


Where to find the LLDP information?

Log in the Administration Portal. From the vertical menu select Compute >
Hosts and choose a host by clicking on its Name link.
Select Network Interfaces > Setup Host Networks. Hover over each interface to reveal a tooltip
with the relevant information.

Non-UI approach

The LLDP information is also exposed via REST API.
More information is available in REST API documentation.