Operation Manual – Routing ProtocolH3C S7500 Series Ethernet Switches Chapter 7 IP Routing Policy Configuration7-77.2.2 Define an IP Prefix ListAn ip-prefix (IP prefix list) is identified by name. Each ip-prefix can include multipleitems, and each item, identified by an index-number, can independently specify thematch range in network prefix form. Index-numbers specify the matching order of theitems in the ip-prefix.Follow these steps to define an IP prefix list:To do... Use the command... RemarksEnter system view system-view —Define an IP prefixlistip ip-prefix ip-prefix-name [ indexindex-number ] { permit | deny } networklen [ greater-equal greater-equal |less-equal less-equal ]*RequiredDuring a matching test, the router checks the items in the ascending order of theirindex-numbers. Once an item is met, the ip-prefix filtering is passed and no other itemwill be checked.Note:Among the items defined in an IP prefix list, at least one item should be in permitmode. The items in deny mode can be used to quickly filter out undesired routinginformation. But if all the items are in deny mode, no route will pass the filter of theIP-prefix list. Therefore, you need to define the permit 0.0.0.0 0 greater-equal 0less-equal 32 item following multiple deny mode items to permit all other routes topass through.7.2.3 Configuring an AS Path ListA BGP routing information packet contains an AS path field, which can be used to filterout the routing information that does not match.Perform the following configuration in system view.Follow these steps to configure an AS path list:To do... Use the command... RemarksEnter system view system-view —Configure an AS path list ip as-path-acl acl-number { permit |deny } as-regular-expression Required
