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Step
3.
Redistribute routes from
other routing protocols or
other IS-IS processes.
4.
(Optional.) Configure the
maximum number of
redistributed Level 1/Level 2
IPv4 routes.
Configuring IS-IS route filtering
You can use an ACL, IP prefix list, or routing policy to filter routes calculated using received LSPs
and routes redistributed from other routing protocols.
Filtering routes calculated from received LSPs
IS-IS saves LSPs received from neighbors in the LSDB, and uses the SPF algorithm to calculate the
shortest path tree with itself as the root. IS-IS installs the calculated routes to the IS-IS routing table
and the optimal routes to the IP routing table.
Perform this task to filter calculated routes. Only routes that are not filtered can be added to the IP
routing table. The filtered routes retain in the IS-IS routing table and can be advertised to neighbors.
To filter routes calculated using received LSPs:
Step
1.
Enter system view.
2.
Enter IS-IS IPv4 unicast
address family view.
3.
Filter routes calculated using
received LSPs.
Filtering redistributed routes
IS-IS can redistribute routes from other routing protocols or other IS-IS processes, add them to the
IS-IS routing table, and advertise them in LSPs.
Perform this task to filter redistributed routes. Only routes that are not filtered can be added to the
IS-IS routing table and advertised to neighbors.
To filter redistributed routes:
Step
1.
Enter system view.
Command
import-route protocol [ as-number ]
[ process-id | all-processes |
allow-ibgp ] [ allow-direct | cost
cost-value | cost-type { external |
internal } | [ level-1 | level-1-2 |
level-2 ] | route-policy
route-policy-name | tag tag ] *
import-route limit number
Command
system-view
a
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
b
cost-style { wide |
wide-compatible }
c
address-family ipv4 [ unicast ]
filter-policy { ipv4-acl-number |
prefix-list prefix-list-name |
route-policy route-policy-name } import
Command
system-view
148
Remarks
By default, no route is
redistributed.
By default, if no level is
specified, this command
redistributes routes into the
Level-2 routing table.
This command redistributes only
active routes. To display active
routes, use the display ip
routing-table protocol
command.
By default, the maximum
number of redistributed Level
1/Level 2 IPv4 routes is not
configured.
Remarks
N/A
N/A
By default, IS-IS route
filtering is not configured.
Remarks
N/A
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Troubleshooting
