Filter
Top Products
DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-15
4.2.6.3 Configuring the Control of Adding
the Aggregate Route to RIB
The network range after the route aggregation may exceed the actual range in the
RIB(Routing Information Base). If the data are sent to the network beyond the
aggregation range, it may result in a loop or the greater burden to the router. It
needs to add a discard route to the RIB in ABR or ASBR to prevent that problem.
To allow or disalllow to add the discard route to the RIB, execute the following
commands in the routing process configuration mode:
Command Function
DES-7200 (config-router)#
discard-route {internal|external}
Allow to add the discard route to the RIB.
DES-7200 (config-router)# no
discard-route {internal|external}
Disallow to add the discard route to the
RIB.
By default, it allows to add the discard route to the RIB.
4.2.7 Creating the Virtual Links
In the OSPF routing area, the OSPF route updating between non-backbone areas
are exchanged via the backbone area to which all the areas are connected. If the
backbone area is disconnected, you need to configure the virtual link to connect
the backbone area. Otherwise, the network communication will fail. If physical
connection cannot be ensured due to the restriction of the network topology, you
can also meet this requirement by creating the virtual links.
Virtual links should be created between two ABRs. The common area of the
ABRs become the transmit areas. The stub areas and NSSA areas cannot be
used as the transit area. The virtual links can be seen as a logical connection
channel established between two ABRs via the transit area. On both its ends
must be ABRs and configuration must be performed on both ends. The virtual link
is identified by the router-id number of the peer router. The area that provides the
two ends of a virtual link with an internal non-backbone area route is referred to
as the transit area, whose number must be specified at configuration.
The virtual links will be activated after the route in the transit area has been
calculated (that is, the route to the other router). You can see it as a point-to-point
connection, on which most parameters of the interface can be configured, like a
physical interface, for example, hello-interval and dead-interval.
The “logical channel” means that the multiple routers running the OSPF between
the two ABRs only forward packets (If the destination addresses of the protocol
packets are not these routers, the packets are transparent to them and are simply