OSPF Area Parameters Plugin

You can use the ospf.areas plugin to configure stub and NSSA areas, area ranges (summarization), or summarization of external NSSA (type-7) routes into external (type-2) routes. These features are considered core features as they’re defined in RFC 2328, RFC 5340, and RFC 1587.

The plugin also supports suppressing inter-area routes in stub/NSSA areas, resulting in totally stubby/NSSA areas. This feature might not be available on all supported platforms.

Supported Platforms

The plugin includes Jinja2 templates for the following platforms:

Operating system	Stub/NSSA areas	Totally stubby areas	Area ranges	NSSA area ranges
Arista EOS	✅ ❗	✅	✅	❌
Aruba CX	✅	✅	✅	✅
Cisco IOS/XE[1]	✅	✅	✅	❌
Cumulus NVUE	✅	✅	✅ ❗	❌
Dell OS10	✅	✅	✅ ❗	❌
FRR	✅	✅	✅ ❗	✅
Junos[2]	✅	✅	✅	✅
SR Linux	✅	✅	✅ ❗	✅

Specifying OSPF Area Parameters

The OSPF area parameters can be specified in global-, node-, or VRF-level ospf.areas list. Each element of the list can have these attributes:

area (mandatory) – OSPF area ID in integer or IPv4 address format.
kind – OSPF area type (stub, nssa, or regular)
default.cost (int) – The cost of the default route inserted into the stub/NSSA area (IPv4 only)
inter_area (bool, default: true) – propagation of inter-area routes into stub/NSSA area. Set to false to implement totally stubby areas.
range – summarization ranges for the area
filter (list of IPv4 or IPv6 prefixes) – not-advertized summarization ranges for the area
external_range – NSSA summarization ranges for the external type-7 routes from this area
external_filter (list of IPv4 or IPv6 prefixes) – not-advertized summarization ranges for the external type-7 routes from this area

The range and external_range parameters are lists of area summarization ranges. Each range can be specified as an IPv4/IPv6 prefix or a dictionary with these parameters:

ipv4 – IPv4 summary prefix
ipv6 – IPv6 summary prefix
cost – The cost of the summary prefix
type (NSSA external_range only) – the external metric type of the summary type-5 LSA (e1 or e2)

Example:

ospf.areas:
# Regular area with a summarization
# range and a no-advertise (filtering) range
# You can specify IPv4 and IPv6 prefixes in the
# same list.

- area: 11
  range:
  - 10.17.0.0/16
  - ipv6: 2001:db8:1::/48
    cost: 42
  filter:
  - 10.18.0.0/16
  - 2001:db8:2::/48

# Totally stubby area

- area: 51
  kind: stub
  inter_area: false

Inheritance of Configuration Parameters

Global (topology) ospf.areas definitions are merged with node ospf.areas definitions, allowing you to define OSPF area parameters for the whole lab topology.
Node ospf.areas definitions are merged with the definitions in VRF instances.
The merge of data is done on the attribute level. For example, the global range parameter would be copied into the node definition if the node definition does not contain that parameter, but will not be appended to an existing node-level range parameter.

You can set most parameters in the node- or VRF definition to False to prevent their inheritance.