Owner's Manual

Chapter 24. OSPF | 679
NETGEAR 8800 User Manual
The translate option determines whether type 7 LSAs are translated into type 5 LSAs. When
configuring an OSPF area as an NSSA,
translate should only be used on NSSA border
routers, where translation is to be enforced. If
translate is not used on any NSSA border
router in a NSSA, one of the ABRs for that NSSA is elected to perform translation (as
indicated in the NSSA specification). The option should not be used on NSSA internal
routers. Doing so inhibits correct operation of the election algorithm.
Normal Area
A normal area is an area that is not:
• Area 0
• Stub area
• NSSA
Virtual links can be configured through normal areas. External routes can be distributed into
normal areas.
Virtual Links
In the situation when a new area is introduced that does not have a direct physical
attachment to the backbone, a virtual link is used. A virtual link provides a logical path
between the ABR of the disconnected area and the ABR of the normal area that connects to
the backbone. A virtual link must be established between two ABRs that have a common
area, with one ABR connected to the backbone.
Figure 72 illustrates a virtual link.
Note: Virtual links cannot be configured through a stub or NSSA area.
Figure 72. Virtual Link Using Area1 as a Transit Area
ABR ABR
Area 2 Area 1 Area 0
Virtual link
EX_044