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3
Create a Layer 3 ACL using permit rules with the count option to describe the desired CPU traffic.
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 affected when you enable egress ACL filtering for CPU traffic.
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
2
Apply the ACL as an inbound or outbound ACL on an interface. Refer to
3
show ip accounting access-list
EXEC Privilege mode
View the number of packets matching the ACL.
IP Prefix Lists
IP prefix lists are supported to control routing policy.
An IP prefix list is a series of sequential filters that contain a matching criterion (examine IP route prefix) and
an action (permit or deny) to process routes. The filters are processed in sequence so that if a route prefix
does not match the criterion in the first filter, the second filter (if configured) is applied. 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 is dropped (that is, implicit deny).
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 should be matched
of the dotted decimal address. 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.
The following examples show permit or deny filters for specific routes using the le and ge 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.
•
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 any permit or deny filters allows all routes.
Configure a Standard IP ACL
Applying an IP
Access Control Lists (ACLs)
Filter.
ACL.
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Troubleshooting
