User guide

9-8 B
LACK
D
IAMOND
U
SER
G
UIDE
R
OUTING
P
ROTOCOLS
Figure 9-2:
Virtual link for stub area
Virtual links are also used to repair a discontiguous backbone area. For example, in
Figure 9-3, 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 9-3:
Virtual link providing redundancy
ABR ABR
BD_013
Virtual link
Area 2 Area 1 Area 0
ABR 1 ABR 2
BD_014
Area 2
Area 1 Area 0 Area 3
Virtual link