User's Manual

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Command Purpose
area
area-id
range
address mask Define the address range for route summary.
60.3.9 Configuring the Gathering of a Forwarding Router
When distributing routes from other router areas to OSPF router area, each performs independent
broadcasting in the form of external LSA. But you can configure the router to broadcast a route, which covers
a certain address range. This method can reduce the size of OSPF link status database.
Under the router configuration mode, use the following command to configure gathering the router:
Command Purpose
summary-address
prefix mask [
not advertise
] Describe the address and mask that cover the
distribution route, only one gathering route is
broadcasted.
60.3.10 Creating Default Route
You can demand ASBR to create a default route to enter into the OSPF route area. Whenever you configure
a router distribute route to enter into OSPF domain, this router automatically changes into ASBR. But, ASBR
does not create default route entering into OSPF route area by default.
Under router configuration mode, use the following command to force ASBR to create a default route:
Command Purpose
default-information originate
[
always
] [
route-
map
map-name]
Force ASBR to create a default route entering
into OSPF route area.
60.3.11 Selecting Router ID Through Loopback Interface
OSPF uses the biggest IP address configured on the interface as its router ID. If the interface connected to
this IP address changes into DOWN state, or this IP address is deleted, OSPF process will restart to calculate
new router ID and resend routing information from all interfaces.
If one loopback interface is configured with IP address, then the router uses that IP address as its router ID,
since loopback interface will never become Down, and all these make the routing table more stable.
The router preferably uses LOOPBACK interface as the router ID, meanwhile selects the biggest IP address
among all loopback interfaces as the router ID. If there is no loopback interface, then uses the biggest IP
address of the router. You cannot designate OSPF to use any special interface.
Under global mode, use the following command, to configure IP Loopback interface.
Command Purpose
interface loopback
0
Create a loopback interface and enter into
interface configuration mode.
ip address
ip-address mask Allocate an IP address for the interface.
60.3.12 Configuring the Management Distance of OSPF
Management distance is defined as the reliability level of routing information source, such as a router or a