packets in the ACL entry, and if the logging is deactivated in a specific interval because the threshold has
exceeded, the count of packets that exceeded the logging threshold value during that interval is recorded
when the subsequent log record (in the next interval) is generated for that ACL entry.
Guidelines for Configuring ACL Logging
Keep the following points in mind when you configure logging of ACL activities:
• During initialization, the ACL logging application tags the ACL rule indices for which a match
condition exists as being in-use, which ensures that the same rule indices are not reused by ACL
logging again.
• The ACL configuration information that the ACL logging application receives from the ACL manager
causes the allocation and clearance of the match rule number. A unique match rule number is
created for the combination of each ACL entry, sequence number, and interface parameters.
• A separate set of match indices is preserved by the ACL logging application for the permit and deny
actions. Depending on the action of an ACL entry, the corresponding match index is allocated from
the particular set that is maintained for permit and deny actions.
• A maximum of 125 ACL entries with permit action can be logged. A maximum of 126 ACL entries with
deny action can be logged.
• For virtual ACL entries, the same match rule number is reused. Similarly, when an ACL entry is deleted
that was previously enabled for ACL logging, the match rule number used by it is released back to the
pool or available set of match indices so that it can be reused for subsequent allocations.
• If you enabled the count of packets for the ACL entry for which you configured logging, and if the
logging is deactivated in a specific interval owing to the threshold having exceeded, the count of
packets that exceeded the logging threshold value during that interval is logged when the subsequent
log record (in the next interval) is generated for that ACL entry.
• When you delete an ACL entry, the logging settings associated with it are also removed.
• ACL logging is supported for standard and extended IPv4 ACLs, IPv6 ACLs, and standard and extended
MAC ACLs.
• For ACL entries applied on port-channel interfaces, one match index for every member interface of
the port-channel interface is assigned. Therefore, the total available match indices of 251 are split (125
match indices for permit action and 126 match indices for the deny action).
• You can configure ACL logging only on ACLs that are applied to ingress interfaces; you cannot enable
logging for ACLs on egress interfaces.
• The total available match rule indices is 255 with four match indices used by other modules, leaving
251 indices available for ACL logging.
Configuring ACL Logging
To configure the maximum number of ACL log messages to be generated and the frequency at which
these messages must be generated, perform the following steps:
Access Control Lists (ACLs) 137