NOTE
l
When the LS age field value (aging time) in the header of an LSA reaches 3600s, the LSA is deleted.
l
If an ASBR also functions as an ABR,
flush-waiting-timer
does not take effect. This prevents
Type 5 LSAs in the non-NSSAs from being deleted.
l
If an ASBR also functions as an ABR, set the parameter
no-import-route
to prevent external
routes imported using the
import-route
command from being advertised to the NSSA.
l
To reduce the number of LSAs that are transmitted to the NSSA, set the parameter
no-
summary
on an ABR. This prevents the ABR from transmitting Type 3 LSAs to the NSSA.
l
After the parameter
set-n-bit
is configured, the switch re-establishes neighbor relationships
with the neighboring switches in the NSSA.
l
If multiple ABRs are deployed in the NSSA, the system automatically selects an ABR
(generally the switch with the largest router ID) as a translator to translate Type 7 LSAs into
Type 5 LSAs. You can also configure the parameter
translator-always
on an ABR to specify
the ABR as an all-the-time translator. To specify two ABRs for load balancing, configure
the parameter
translator-always
on two ABRs to specify the ABRs as all-the-time
translators. This prevents LSA flooding caused by translator role changes.
l
The parameter
translator-interval
is used to ensure uninterrupted services when translator
roles change. The
interval-value
value must be greater than the flooding period.
Step 5
(Optional)Run:
default-cost
cost
The cost of the default route to the NSSA is set.
To ensure the reachability of AS external routes, the ABR in the NSSA generates a default route
and advertises the route to the other switches in the NSSA.
Type 7 LSAs can be used to carry default route information to guide traffic to other ASs.
Multiple ABRs may be deployed in an NSSA. To prevent routing loops, ABRs do not calculate
the default routes advertised by each other.
By default, the cost of the default route to the NSSA is 1.
----End
Checking the Configuration
Run either of the following commands to check LSDB information.
l
display ospf
[
process-id
]
lsdb
[
brief
]
l
display ospf
[
process-id
]
lsdb
[
router
|
network
|
summary
|
asbr
|
ase
|
nssa
|
opaque-
link
|
opaque-area
|
opaque-as
] [
link-state-id
] [
originate
-
router
[
advertising-router-
id
] |
self
-
originate
]
Run either of the following commands to check routing table information.
l
display ospf
[
process-id
]
routing
[
ip-address
[
mask
|
mask-length
] ] [
interface
interface-type
interface-number
] [
nexthop
nexthop-address
]
l
display ospf
[
process-id
]
routing
router-id
[
router-id
]
Run the
display ospf
[
process-id
]
interface
[
all
|
interface-type
interface-number
]
[
verbose
] command to check OSPF interface information.
S6700 Series Ethernet Switches
Configuration Guide - IP Routing
4 OSPF Configuration
Issue 01 (2012-03-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
120
