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monitor (OPTIONAL) Enter the keyword monitor when the rule is describing the traffic
that you want to monitor and the ACL in which you are creating the rule is applied
to the monitored interface.
Defaults By default, 10 ACL logs are generated if you do not specify the threshold explicitly. The default frequency
at which ACL logs are generated is five minutes. By default, flow-based monitoring is not enabled.
Command Modes CONFIGURATION-STANDARD-ACCESS-LIST
Supported Modes Full–Switch
Command
History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.4(0.0) Added support for flow-based monitoring on the MXL 10/40GbE Switch IO Module
platforms.
9.3(0.0) Added support for logging of ACLs on the MXL 10/40GbE Switch IO Module
platforms.
Usage
Information
When the configured maximum threshold is exceeded, generation of logs is stopped. When the interval
at which ACL logs are configured to be recorded expires, the 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
deny — assigns a IP ACL filter to deny IP packets.
ip access-list standard — creates a standard ACL.
seq
Assign a sequence number to a deny or permit filter in an extended IP access list while creating the filter.
Syntax
seq sequence-number {deny | permit} {source [mask] | any | host ip-
address}} [count [byte] [dscp value] [order] [fragments] [threshold-in-msgs
[count]
Parameters
sequence-
number
Enter a number from 0 to 4294967290. The range is from 0 to 65534.
deny Enter the keyword deny to configure a filter to drop packets meeting this
condition.
permit Enter the keyword permit to configure a filter to forward packets meeting this
criteria.
source Enter an IP address in dotted decimal format of the network from which the packet
was received.
Access Control Lists (ACL) 149