Extreme Networks ExtremeWare XOS Guide Manual page 192

Interior Gateway Protocols
Figure 33: 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 Figure 34, if the
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 34: Virtual link providing redundancy
Area 1
192
Virtual link
ABR
Area 1
Virtual link
Area 2
ABR 1
Area 0
ABR
Area 0
ABR 2
Area 3
ExtremeWare XOS 10.1 Concepts Guide
EX_044
EX_045