Extreme Networks BlackDiamond 6800 User Manual page 138

R P
OUTING ROTOCOLS
Virtual link
ABR
Area 2
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.
Virtual link
ABR 1
Area 1
Figure 9-3: Virtual link providing redundancy
9-8
ABR
Area 1
Area 2
Area 0
Area 0
BD_013
ABR 2
Area 3
BD_014
B D U G
LACK IAMOND SER UIDE