Principles and configurations of the BGP protocol for HCNP learning notes 3-route Aggregation

Source: Internet
Author: User

Principles and configurations of the BGP protocol for HCNP learning notes 3-route Aggregation
The BGP protocol can use commands to aggregate specific routes into an aggregation route. The Routing aggregation principle adopts the longest matching method with the same mask. Route aggregation can reduce the size of the route table. No Route details can be used to reduce the number of route changes. It does not trigger the number of Route switches. 1 is automatically aggregated (not used in the current network, with poor controllability, can only be aggregated into the main class network) after automatic aggregation is configured, the aggregated natural network segment routing is generated, and the original introduced subnet routing is blocked and will not be optimized and published to BGP peers. Summary automatic // used to enable automatic aggregation of the introduced routes. undo summary automatic // The command is used to cancel automatic aggregation of the introduced routes. By default, automatic aggregation of introduced routes is not performed, that is, only the introduced routes are aggregated. 2. Manual aggregation generally has a higher priority than automatic aggregation. By default, route aggregation is not performed. By default, the detailed route and the aggregated route are published together after manual aggregation. Aggregate ip-address mask [as-set | attribute-policy route-policy-name1 | detail-suppressed | origin-policy route-policy-name2 | suppress-policy route-policy-name3] // Manual aggregation, detail-suppressed (Suppress details) 3 problems caused by route aggregation as-setBGP route Aggregation problems to be considered release of detailed routes BGP Route attributes inherit AS-Path Origin Community...... The AS-Path attribute of an aggregate route does not contain any other AS information, and the AS-PATH information of all specific routes is lost. It indicates that the aggregated route without the AS_SET parameter is considered to be generated by RTC. Aggregate detail-suppressed as-set // used to aggregate as-path information. It is important to add the aggregated as-path to AS_SET information to avoid routing loops, because it records the AS of the aggregated route. 4. Change the route aggregation attribute ?? Attribute-policy aggregation routes do not inherit the original BGP Route attributes. You can run the following command to modify the attributes of an aggregation route: You can configure the attribute-policy parameter to modify the attributes of a BGP aggregation route. 5. filter the route orgin-policy suppress-Rule yorigin-policy: select the part that meets the policy) route aggregation acl number 2001 rule deny source 0 rule permit source any route-policy orgin permit node 20 if-match acl 2001 aggregate detail-suppressed as-set origin-policy origin suppress -policy: suppress some routes (suppress all by default) acl number 2002 rule permit source permit source suppress permit node 10 if-match acl 2002 aggregate detail-suppressed as-set origin-policy origin suppress-policy suppress

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