use a route-map to limit redistribution in OSPF

您正在看的网络管理员教程是:use a route-map to limit redistribution in OSPF。
　　! /* match only 172.16.10.x and 172.16.11.0 subnets */
　　!
　　access-list 1 permit 172.16.10.0 0.0.1.255
　　!
　　!
　　! /* use access-list 1 to determine what gets matched */
　　!
　　route-map LoopbacksOnly permit 10
　　match ip address 1
　　!
　　!
　　! /* redistribute connected networks, any and all subnets, */
　　! /* and seed it as E2 type. Note that throughout your */
　　! /* OSPF domain, your loopbacks will have a metric of 20 */
　　! /* 20 is the default metric when you redistribute into */
　　! /* OSPF. Except for BGP routes which get a metric of 1. */
　　! /* Also use the route-map LoopbacksOnly to selectively */
　　! /* redistribute only the ones we want to redistribute. */
　　!
　　router ospf 200
　　redistribute connected subnets metric-type E2 route-map LooopbacksOnly