Extreme Networks ExtremeWare XOS Guide Manual page 388

Interior Gateway Protocols
Figure 58: Virtual link using area 1 as a transit area
Area 2
Virtual links are also used to repair a discontiguous backbone area. For example, in
connection between ABR1 and the backbone fails, the connection using ABR2 provides redundancy so
that the discontiguous area can continue to communicate with the backbone using the virtual link.
Figure 59: Virtual link providing redundancy
Virtual link
ABR 1
Area 1
ExtremeWare XOS 11.1 Concepts Guide
Virtual link
ABR
Area 1
Area 2
Area 0
ABR
Area 0
ABR 2
Area 3
EX_044
Figure 59, if the
EX_045
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