Users Guide

CONFIG-NACL mode
permit ip {source mask | any | host ip-address} {destination mask | any | host ip-address}
count
Dell Networking OS Behavior: Virtual router redundancy protocol (VRRP) hellos and internet group management protocol (IGMP) packets
are not aected when you enable egress ACL ltering for CPU trac. Packets sent by the CPU with the source address as the VRRP
virtual IP address have the interface MAC address instead of VRRP virtual MAC address.
Counting ACL Hits
You can view the number of packets matching the ACL by using the count option when creating ACL entries.
1 Create an ACL that uses rules with the count option. Refer to Congure a Standard IP ACL Filter.
2 Apply the ACL as an inbound or outbound ACL on an interface. Refer to Applying an IP ACL.
3 show ip accounting access-list
EXEC Privilege mode
View the number of packets matching the ACL.
IP Prex Lists
IP prex lists are supported to control routing policy.
An IP prex list is a series of sequential lters that contain a matching criterion (examine IP route prex) and an action (permit or deny) to
process routes. The lters are processed in sequence so that if a route prex does not match the criterion in the rst lter, the second lter
(if congured) is applied. When the route prex matches a lter, the system drops or forwards the packet based on the lter’s designated
action. If the route prex does not match any of the lters in the prex list, the route is dropped (that is, implicit deny).
A route prex is an IP address pattern that matches on bits within the IP address. The format of a route prex is A.B.C.D/X where A.B.C.D
is a dotted-decimal address and /X is the number of bits that should be matched of the dotted decimal address. For example, in
112.24.0.0/16, the rst 16 bits of the address 112.24.0.0 match all addresses between 112.24.0.0 to 112.24.255.255.
The following examples show permit or deny lters for specic routes using the le and ge parameters, where x.x.x.x/x represents a route
prex:
• To deny only /8 prexes, 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.
• 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 prex lists:
• A prex list without any permit or deny lters allows all routes.
• An “implicit deny” is assumed (that is, the route is dropped) for all route prexes that do not match a permit or deny lter in a
congured prex list.
• After a route matches a lter, the lter’s action is applied. No additional lters are applied to the route.
Implementation Information
Prex lists are used in processing routes for routing protocols (for example, router information protocol [RIP], open shortest path rst
[OSPF], and border gateway protocol [BGP]).
Access Control Lists (ACLs)
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