Network Protocol Manager for IS-IS creates a full adjacency between two peering IS-IS devices if both IS-IS neighbor endpoints are discovered in the managed IS-IS topology. If only one IS-IS neighbor endpoint is discovered in the managed IS-IS topology, Network Protocol Manager for IS-IS creates a stub adjacency between the two peering IS-IS devices. The presence of a gray router icon in an ISIS Connectivity map indicates one or more stub adjacencies.
An ISIS Connectivity map that shows a stub adjacency shows a stub adjacency, which is represented as a solid green line connected to a gray router icon. Green indicates that the stub adjacency is healthy. The device that is represented by the gray router icon is not present in the repository of Network Protocol Manager for BGP.
Displaying stub adjacencies enables a service provider to show a subscriber the status of that subscriber’s adjacency from the provider’s perspective.