Verilink 9000 Series (34-00271) Product Manual - Manual (Page 322)

300 C HAPTER 18: IP R OUTER
Address Summary
A configured address range specifies what addresses are contained within an area.
When summarizing the routes in an area to inform other areas, all routes falling
within the configured range are described by a single LSA, thus decreasing the
size of the LSA database.
Address Summary Mask
IP Mask of Summary to be added.
Authentication Type
The OSPF protocol allows that all exchanges between routers (gateways) are
authenticated (verified and approved). The idea is to allow only trusted routers to
propagate routing information. This feature does not exist in RIP. This also
discourages malicious persons from using personal computers to send RIP
messages advertising low-cost routes all over the place. This may result in many
routers, running RIP, to change their routes and start sending IP datagram packets
to the personal computer. The default value is none, that is, N.
This is a Stub Area
Here is an excerpt of the RFC related to OSPF Version 2:
In some Autonomous Systems, the majority of the topological database may
consist of AS external advertisements. An OSPF AS external advertisement is
usually flooded throughout the entire AS. However, OSPF allows certain areas
to be configured as "stub areas." AS external advertisements are not flooded
into/throughout stub areas; routing to AS external destinations in these areas is
based on a (per-area) default only. This reduces the topological database size,
and therefore the memory requirements, for a stub area's internal routers. In
order to take advantage of the OSPF stub area support, default routing must be
used in the stub area. This is accomplished as follows. One or more of the stub
area's area border routers must advertise a default route into the stub area via
summary link advertisements. These summary defaults are flooded throughout
the stub area, but no further. (For this reason these defaults pertain only to the
particular stub area). These summary default routes will match any destination
that is not explicitly reachable by an intra-area or inter-area path (i.e., AS
external destinations). An area can be configured as stub when there is a single
exit point from the area, or when the choice of exit point need not be made on
a per-external-destination basis...
The OSPF protocol ensures that all routers belonging to an area agree on
whether the area has been configured as a stub. This guarantees that no
confusion will arise in the flooding of AS external advertisements.
There are a couple of restrictions on the use of stub areas. Virtual links cannot
be configured through stub areas. In addition, AS boundary routers cannot be
placed internal to stub areas.
The default area is No.