H3C Technologies H3C S3600 Series Switches - Manual (Page 347)

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z The import-route command cannot import the default route. To import the default route, you must
use the default-route-advertise command.
z The filtering of advertised routes by OSPF means that OSPF only converts the external routes
meeting the filter criteria into Type-5 or Type-7 LSAs and advertises them.
z When enabling OSPF to import external routes, you can also configure the defaults of some
additional parameters, such as cost, limit, tag, and type. A route tag can be used to identify
protocol-related information.
OSPF Network Adjustment and Optimization
You can adjust and optimize an OSPF network in the following aspects:
z By changing the OSPF packet timers, you can adjust the convergence speed of the OSPF network
and the network load brought by OSPF packets. On some low-speed links, you need to consider
the delay experienced when the interfaces transmit LSAs.
z By Adjusting SPF calculation interval, you can mitigate resource consumption caused by frequent
network changes.
z In a network with high security requirements, you can enable OSPF authentication to enhance
OSPF network security.
z In addition, OSPF supports network management. You can configure the binding of the OSPF MIB
with an OSPF process and configure the Trap message transmission and logging functions.
Configuration Prerequisites
Before adjusting and optimizing an OSPF network, perform the following tasks:
z Configuring the network layer addresses of interfaces so that the adjacent nodes are reachable to
each other at the network layer
z Configuring basic OSPF functions
Configuring OSPF Timers
The Hello intervals for OSPF neighbors must be consistent. The value of Hello interval is in inverse
proportion to route convergence speed and network load.
The dead time on an interface must be at least four times of the Hello interval on the same interface.
After a router sends an LSA to a neighbor, it waits for an acknowledgement packet from the neighbor. If
the router receives no acknowledgement packet from the neighbor within the retransmission interval, it
retransmits the LSA to the neighbor.
Follow these steps to configure OSPF timers:
To do... Use the command... Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—