connection
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... backbone area (area 0) and all other areas must have either
physical or virtual connections to the backbone. The reason for this
star-like topology ...
... R1 and R2 have backbone
connections, while R3 doesn't.
Following the section 12.4.1 of [Ref1 ...
... this case, router R3 will have a virtual backbone connection, will
form an adjacency over it, will receive all LSAs directly from a
...
... a single access point into one area while still offering a redundant
connection through another access point in a different area, as shown
in Figure 2.
...
... ABR has no
backbone connection. They imply that a router connected to multiple
areas without a backbone ...
... router connected to multiple
areas without a backbone connection is not an ABR and should function
as a router ...
... physical backbone
connection at all. The methods described here improve the behavior
of a router ...
... router is considered to have an active backbone connection if
the backbone area is actively attached and there is at least one
...
... or it does not have an Active Backbone Connection. Definitions
of the terms used in this paragraph are given in section 2.1.
...
... have an Active Backbone Connection (and, consequently, examines
summaries from all attached areas). The algorithm is changed to
...
... Active Backbone
Connection, it can originate Type 4 summary-LSA only if the
type of the route ...