Dell PowerSwitch S4112F-ON EMC SmartFabric OS10 User Guide Release 10.5.1 - Page 1247

Clear access-list counters Clear IPv4, IPv6, or MAC access-list counters for a specific access-list or all lists. The counter counts the number of packets that match each permit or deny statement in an access-list. To get a more recent count of packets matching an access-list, clear the counters to start at zero. If you do not configure an access-list name, all IP access-list counters clear. To view access-list information, use the show access-lists command. ● Clear IPv4 access-list counters in EXEC mode. clear ip access-list counters access-list-name ● Clear IPv6 access-list counters in EXEC mode. clear ipv6 access-list counters access-list-name ● Clear MAC access-list counters in EXEC mode. clear mac access-list counters access-list-name IP prefix-lists IP prefix-lists control the routing policy. An IP prefix-list is a series of sequential filters that contain a matching criterion and an permit or deny action to process routes. The filters process in sequence so that if a route prefix does not match the criterion in the first filter, the second filter applies, and so on. A route prefix is an IP address pattern that matches on bits within the IP address. The format of a route prefix is A.B.C.D/x, where A.B.C.D is a dotted-decimal address and /x is the number of bits that match the dotted decimal address. When the route prefix matches a filter, the system drops or forwards the packet based on the filter's designated action. If the route prefix does not match any of the filters in the prefix-list, the route drops, an implicit deny. For example, in 112.24.0.0/16, the first 16 bits of the address 112.24.0.0 match all addresses between 112.24.0.0 to 112.24.255.255. Use permit or deny filters for specific routes with the le (less or equal) and ge (greater or equal) parameters, where x.x.x.x/x represents a route prefix: ● To deny only /8 prefixes, enter deny x.x.x.x/x ge 8 le 8 ● To permit routes with the mask greater than /8 but less than /12, enter permit x.x.x.x/x ge 8 le 12 ● To deny routes with a mask less than /24, enter deny x.x.x.x/x le 24 ● To permit routes with a mask greater than /20, enter permit x.x.x.x/x ge 20 The following rules apply to prefix-lists: ● A prefix-list without permit or deny filters allows all routes ● An implicit deny is assumed - the route drops for all route prefixes that do not match a permit or deny filter ● After a route matches a filter, the filter's action applies and no additional filters apply to the route NOTE: Use prefix-lists in processing routes for routing protocols such as open shortest path first (OSPF), route table manager (RTM), and border gateway protocol (BGP). To configure a prefix-list, use commands in PREFIX-LIST and ROUTER-BGP modes. Create the prefix-list in PREFIX-LIST mode and assign that list to commands in ROUTER-BGP modes. Route-maps Route-maps are a series of commands that contain a matching criterion and action. They change the packets meeting the matching criterion. ACLs and prefix-lists can only drop or forward the packet or traffic while route-maps process routes for route redistribution. For example, use a route-map to filter only specific routes and to add a metric. ● Route-maps also have an implicit deny. Unlike ACLs and prefix-lists where the packet or traffic drops, if a route does not match the route-map conditions, the route does not redistribute. ● Route-maps process routes for route redistribution. For example, to add a metric, a route-map can filter only specific routes. If the route does not match the conditions, the route-map decides where the packet or traffic drops. The route does not redistribute if it does not match. Access Control Lists 1247