Ospf configuration examples, Basic ospf configuration example, Configuring is-is route redistribution – H3C Technologies H3C S12500-X Series Switches User Manual

Page 150: Configuring is-is route filtering

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Configuring IS-IS route redistribution

Perform this task to redistribute routes from other routing protocols into IS-IS. You can specify a cost for

redistributed routes and specify the maximum number of redistributed routes.
To configure IS-IS route redistribution from other routing protocols:

Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter IS-IS view.

isis [ process-id ] [ vpn-instance
vpn-instance-name ]

N/A

3.

Redistribute routes from
other routing protocols

or other IS-IS processes.

import-route protocol [ process-id |
all-processes | allow-ibgp ] [ cost cost
| cost-type { external | internal } |

[ level-1 | level-1-2 | level-2 ] |

route-policy route-policy-name | tag
tag ] *

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.

4.

(Optional.) Configure
the maximum number of

redistributed Level
1/Level 2 IPv4 routes.

import-route limit number

By default, the maximum number of
redistributed Level 1/Level 2 IPv4
routes is not configured.

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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.

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Filtering routes calculated from received LSPs

IS-IS saves LSPs received from neighbors in the LSDB, uses the SPF algorithm to calculate the shortest path

tree with itself as the root, and installs the routes to the IS-IS routing table. IS-IS installs 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 Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter IS-IS view.

isis [ process-id ] [ vpn-instance
vpn-instance-name ]

N/A

3.

Filter routes calculated

using received LSPs.

filter-policy { acl-number | prefix-list
prefix-list-name | route-policy
route-policy-name } import

By default, IS-IS route
filtering is not configured.

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