3Com Switch 7750 Configuration Guide

316 CHAPTER 34: OSPF CONFIGURATION
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■ The import-route command cannot import a default route. To import the
default route, you must use the default-route-advertise command.
■ 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.
■ When enabling OSPF to import external routes, you can also configure the
defaults of some additional parameters, such as cost, number of routes, tag,
and type. A route tag can be used to identify protocol-related information.
■ The allow-ibgp keyword is used to redistribute iBGP routes. Because the
AS-PATH attribute of redistributed iBGP routes is discarded, routing loops may
occur. Therefore, use this keyword with caution.
OSPF Network
Adjustment and
Optimization
You can adjust and optimize an OSPF network in the following aspects:
■ 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.
■ By Adjusting SPF calculation interval, you can mitigate resource consumption
caused by frequent network changes.
■ In a network with high security requirements, you can enable OSPF
authentication to enhance OSPF network security.
■ 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.
Enable OSPF to redistribute a
default route
default-route-advertise
[ always | cost value | type
type-value | route-policy
route-policy-name ]*
Optional
By default, OSPF does not
redistribute the default
route.
Configure the default cost for
redistributed routes
default cost value Optional
By default, the cost for OSPF
to import external routes is
1.
Configure the default
maximum number of external
routes imported by OSPF per
unit time
default limit routes Optional
By default, a maximum of
1000 routes can be
imported.
Configure the default tag for
redistributed routes
default tag tag Optional
The default tag is 1 by
default.
Configure the default type for
redistributed routes
default type { 1 | 2 } Optional
By default, the type of
redistributed routes is
Type-2.
Table 241 Configure OSPF route redistribution
Operation Command Description