Users Guide

subsequent, fresh interval timer is started and the packet count for that new interval
commences from zero. If ACL logging was stopped previously because 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 for standard
and extended IPv4 ACLs, IPv6 ACLs, and MAC ACLs. You can configure ACL logging
only on ACLs that are applied to ingress interfaces; you cannot enable logging for ACLs
that are associated with egress interfaces.
You can activate flow-based monitoring for a monitoring session by entering the flow-
based enable command in the Monitor Session mode. When you enable this
capability, traffic with particular flows that are traversing through the ingress and egress
interfaces are examined and, appropriate ACLs can be applied in both the ingress and
egress direction. Flow-based monitoring conserves bandwidth by monitoring only
specified traffic instead all traffic on the interface. This feature is particularly useful
when looking for malicious traffic. It is available for Layer 2 and Layer 3 ingress and
egress traffic. You may specify traffic using standard or extended access-lists. This
mechanism copies all incoming or outgoing packets on one port and forwards (mirrors)
them to another port. The source port is the monitored port (MD) and the destination
port is the monitoring port (MG).
Related
Commands
• permit — configure a MAC address filter to pass packets.
• seq — configure a MAC address filter with a specified sequence number.
deny (for Extended MAC ACLs)
To drop packets that match the filter criteria, configure a filter.
Syntax
deny {any | host mac-address | mac-source-address mac-source-
address-mask} {any | host mac-address | mac-destination-address
mac-destination-address-mask} [ethertype-operator] [count [byte]]
[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’s sequence
number.
• Use the no deny {any | host mac-address | mac-source-address
mac-source-address-mask} {any | host mac-address | mac-
destination-address mac-destination-address-mask} command.
Parameters
log (OPTIONAL) Enter the keyword log to enable the triggering of
ACL log messages.
threshold-in msgs
count
(OPTIONAL) Enter the threshold-in-msgs keyword followed
by a value to indicate the maximum number of ACL logs that
Access Control Lists (ACL) 362