Configuring OSPF to Filter LSAs to Be Sent

Filtering the LSAs to be sent on the local router can prevent unnecessary LSA transmission. This reduces the size of the LSDB on the neighboring device and speeds up network convergence.

Context

When multiple links exist between two devices, you can configure the local device to filter the LSAs to be sent. This prevents unnecessary LSA transmission and saves bandwidth resources.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run interface interface-type interface-number

    The interface view is displayed.

  3. Based on the basic ACL:

    1. Run quit

      Return to the system view.

    2. Run acl { name basic-acl-name { basic | [ basic ] number basic-acl-number } | [ number ] basic-acl-number } [ match-order { config | auto } ]

      The basic ACL view is displayed.

    3. Run rule [ rule-id ] [ name rule-name ] { deny | permit } [ fragment-type { fragment | non-fragment | non-subseq | fragment-subseq | fragment-spe-first } | source { source-ip-address { source-wildcard | 0 | src-netmask } | any } | time-range time-name | vpn-instance vpn-instance-name ] *

      A rule for the basic ACL is configured.

      When the rule command is run to configure rules for a named ACL, only the source address range specified by source and the time period specified by time-range are valid as the rules.

      When a filtering policy of a routing protocol is used to filter routes:
      • If the action specified in an ACL rule is permit, a route that matches the rule will be received or advertised by the system.

      • If the action specified in an ACL rule is deny, a route that matches the rule will not be received or advertised by the system.

      • If a route has not matched any ACL rules, the route will not be received or advertised by the system.

      • If an ACL does not contain any rules, all routes matching the route-policy that references the ACL will not be received or advertised by the system.

      • In the configuration order, the system first matches a route with a rule that has a smaller number and then matches the route with a rule with a larger number. Routes can be filtered using a blacklist or a whitelist:

        Route filtering using a blacklist: Configure a rule with a smaller number and specify the action deny in this rule to filter out the unwanted routes. Then, configure another rule with a larger number in the same ACL and specify the action permit in this rule to receive or advertise the other routes.

        Route filtering using a whitelist: Configure a rule with a smaller number and specify the action permit in this rule to permit the routes to be received or advertised by the system. Then, configure another rule with a larger number in the same ACL and specify the action deny in this rule to filter out unwanted routes.

    4. Run quit

      Return to the system view.

    5. Run interface interface-type interface-number

      The interface view is displayed.

    6. Run ospf filter-lsa-out { all | { summary [ acl { acl-number | acl-name } ] | ase [ acl { acl-number | acl-name } ] | nssa [ acl { acl-number | acl-name } ] } * }

      The OSPF interface is enabled to filter outgoing LSAs.

  4. Run commit

    The configuration is committed.

Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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