492 CHAPTER 37: R OUTING POLICY CONFIGURATIONDefining an ExtendedCommunity ListYou can define multiple items for an extended community list that is identified bynumber. During matching, the relation between items is logic OR, that is, ifrouting information matches one of these items, it passes the extendedcommunity list.Follow these steps to define an extended community list:Configuring a RoutingPolicyA routing policy is used to filter routing information according to some attributes,and modify some attributes of the routing information that matches the routingpolicy. Match criteria can be configured using filters above mentioned.A routing policy can comprise multiple nodes, each node contains:■ if-match clauses: Define the match criteria that routing information mustsatisfy. The matching objects are some attributes of routing information.■ apply clauses: Specify the actions performed after specified match criteria aresatisfied, concerning attribute settings for passed routing information.Prerequisites Before configuring this task, you have completed:■ Filtering list configuration■ Routing protocol configurationYou also need to decide on:■ Name of the routing policy, node sequence numbers■ Match criteria■ Attributes to be modifiedDefine acommunity listDefine a basiccommunity listip community-listbasic-comm-list-num{ deny | permit }[ community-number-list ] [ internet |no-advertise |no-export |no-export-subconfed] *Required to defineeither;Not defined by defaultDefine an advancedcommunity listip community-listadv-comm-list-num{ deny | permit }regular-expressionTo do… Use the command… RemarksTo do… Use the command… RemarksEnter system view system-view -Define an extendedcommunity listip extcommunity-listext-comm-list-number { deny| permit } { rtroute-target }&<1-16>RequiredNot defined by default
