new interval commences from zero. If ACL logging was stopped previouslybecause the configured threshold is exceeded, it is re-enabled for this new interval.If ACL logging is stopped because the configured threshold is exceeded, it is re-enabled after the logging interval period elapses. ACL logging is supported forstandard and extended IPv4 ACLs, IPv6 ACLs, and MAC ACLs. You can configureACL logging only on ACLs that are applied to ingress interfaces; you cannot enablelogging for ACLs that are associated with egress interfaces.You can activate flow-based monitoring for a monitoring session by entering theflow-based enable command in the Monitor Session mode. When you enable thiscapability, traffic with particular flows that are traversing through the ingress andegress interfaces are examined and, appropriate ACLs can be applied in both theingress and egress direction. Flow-based monitoring conserves bandwidth bymonitoring only specified traffic instead all traffic on the interface. This feature isparticularly useful when looking for malicious traffic. It is available for Layer 2 andLayer 3 ingress and egress traffic. You may specify traffic using standard orextended access-lists. This mechanism copies all incoming or outgoing packets onone port and forwards (mirrors) them to another port. The source port is themonitored port (MD) and the destination port is the monitoring port (MG).deny icmp (for Extended IP ACLs)To drop all or specific internet control message protocol (ICMP) messages, configure a filter.NOTE: Only the options that have been newly introduced in Release 9.3(0.0) and Release 9.4(0.0)are described here. For a complete description on all of the keywords and variables that areavailable with this command, refer the topic of this command discussed earlier in this guide.Syntax deny icmp {source mask | any | host ip-address} {destinationmask | any | host ip-address} [dscp] [message-type] [count[byte]] [order] [fragments] [log [interval minutes] [threshold-in-msgs [count]] [monitor]To remove this filter, you have two choices:• Use the no seq sequence-number command if you know the filter’ssequence number.• Use the no deny icmp {source mask | any | host ip-address}{destination mask | any | host ip-address} command.Parameters log (OPTIONAL) Enter the keyword log to enable the triggeringof ACL log messages.threshold-inmsgs count(OPTIONAL) Enter the threshold-in-msgs keywordfollowed by a value to indicate the maximum number of ACLlogs that can be generated, exceeding which the generationof ACL logs is terminated with the seq, permit, or denycommands. The threshold range is from 1 to 100.308 Access Control Lists (ACL)
