Lab Topology Reference

The lab topology is described in a YAML file using a dictionary format. You could use hierarchical attribute names as dictionary keys to make the topology file more readable.

The three major components that should be present in every topology file are:

nodes – lab devices (nodes)
links – links between the lab devices
defaults – topology-wide defaults like default device type

Other topology elements include:

addressing – IPv4 and IPv6 pools used to address management, loopback, LAN, P2P and stub interfaces
components – reusable components that you can include in multiple places in the lab topology
groups – optional groups of nodes
module – default list of modules used by this network topology. You can use device-level module attribute to override this setting for individual nodes.
plugin – list of plugins used by this topology.
prefix – named IP prefixes that can be used to address links and VLANs or in prefix lists or validation expressions.
tools – dictionary of external network management tools deployed after the lab has been started and configured.
validate – lab validation tests

Finally, you can set these topology-level parameters:

provider – virtualization provider (default: libvirt)
message – a help message to display after successful netlab initial or netlab up commands. You can use that message to tell the end-user how to use the lab (example: VLAN integration test cases).
name – topology name (used in bridge names)
version – minimum netlab version required to use this lab topology[1]. You can use either a simple version number or Python module version specification (example: >= 1.6.3). See Version-Specific Lab Topology Files for more details.

Notes:

All elements apart from nodes are optional – missing links element indicates a topology without inter-node links (just the management interfaces)
Default values of defaults and addressing elements are taken from default settings.
List of modules is used to specify additional initial configuration elements (example: OSPF routing)
Default topology name is the directory name[2].

You’ll find sample topology files in the tutorials.

Topology Components