The relationship built between two intermediate systems attached to a common physical link (network). Level 1 adjacencies are built between two systems within the same routing domain (area), while level 2 adjacencies are typically built between intermediate systems within two different routing domains.


Authority Format Identifier. Identifies the authority that granted the use of a particular OSI address and the format of that address.


A section of a device's OSI address which describes the logical location of the device in the network. While the area is a specific part of the OSI address, a subsection of the HO-DSP, intermediate systems view the entire OSI address to the left of the system ID as the area.

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