Primarily used in Service Provider core networks
- Link State Protocol / Flooding domain
- Dijkstra Shortest Path First Algorithm
- Forms Level 1 / Level 2 adjacency via flooding with neighbors
- Backbone / Spine Level 2
- Best use case IGP connectivity for MPLS label Switch paths
- Highly scalable Leaf – Spine – Leaf
- Supports both IPv4, and IPv6 address families
- Control Plane FIB
- Data Plane RIB
Brief History
RFC – 1195
ISO 10589 was not originally developed for IP routing rather part of of the CLNS stack of connectionless networks.
Similar in logic or hierarchy to that of OSPF Leaf – Spine – Leaf.
As mentioned above originally supported only CLNS routing.
Open Shortest Path First Algorithm
- Dijkstra Shortest Path First Algorithm
- Level 1 / Level 2 database
- Level 2 as the backbone area
Key Terms
- NET: Network Entity Title
- NSAP: Network Service Attachment Point
- NSAP Format: [ 49.AAAA ].[ SSSS.SSSS.SSSS.SSSS ].[ NN ]
Key Points
- The NET address must be unique within each area
- The NET actually defines the [ area ] not the level or flooding domain
- The equivalent of Area 0 ( Backbone / Spine ) in OSPF is Level 2
- The Router ID is CLNS address
- Utilizes ISO NSAP addressing. In most cases the NET would begin with 49 which similar to that of RFC 1918
- Minimum length of 8 bytes, and maximum length 20 bytes
- Area based, however the Link State is handled by the Levels
- System ID or Router ID inside the area
- N Selector always zero
- Extensibility in the form of Type Length Values or TLVs
Levels
- Level 1 – This would be considered the a Stub area
- Level 2 – This is equivalent to the backbone area or area 0 found in OSPF
- Flooding occurs within Level 1 and Level 2 as opposed to the NET
